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October 3rd, 2025

Long-Term Powder Storage — What You Need to Know

Western Powders Blog SAAMI Storage

SUMMARY: Powder can have a very long shelf life. You need to watch for changes in smell and color. A reddish tinge, almost like rust on the powder, is a bad sign, as is a foul odor, not to be confused with a normal chemical smell. Either of these signs indicate it is time to dispose of your powder by means other than shooting.

Ever wondered about the stability of the propellants in your reloading room? There are some important things you should know about powder storage, to ensure consistent powder performance and safety. Western Powders (which has been acquired by Hodgdon) published an informative Q & A series entitled Dear Labby: Questions for our Ballistics Lab . Here are some excerpts that pertain to powder storage and shelf life. Worried that your powder may be too old? Western’s experts explain how to check your propellants for warning signs.

Proper Powder Storage

Q: I live in southern Arizona where it is very hot. I am told powders will become unstable if stored in an area not air-conditioned. My wife says no powder or primers in the house. Can powder be stored in a refrigerator? What about using a fireproof safe? I would appreciate your ideas. — M.C.

Lab Answer: SAAMI guidelines are pretty clear on issues of storage. They recommend storing smokeless powder in containers that will not allow pressure to build if the powder is ignited — ruling out gun safes and refrigerators.

CLICK HERE to Read SAAMI Guidelines for Powder Storage (PDF)

In their original containers, the lifespan of smokeless powders is quite long, even in hot, arid climates. In fact the lifespan is typically longer than the average handloader would need to store them. Stored safely in a garage or outbuilding, your powder should last years. If you see the powder developing a reddish tint, or giving off a foul odor, it is time to discard it.

Clumps in Powder Container

Q: I ordered some of your Accurate 1680 powder back about in December. I just now opened it … and it is full of clumps. My knowledge tells me that means moisture. Am I wrong? I just now broke the seal and it has been stored in a ammo can with desiccant packs around it and a dehumidifier running 14-16 hours a day. I can’t imagine this being my fault, if this does indicate moisture. I don’t know if the pink part on the label is suppose to be red or not, but it is definitely pink, so if it was red I am wondering if I was shipped an old container? I hope that this isn’t bad and I am stuck with it…

Lab Answer: All powder contains a certain amount of moisture. When the powder is stored or during shipping, it can go through temperature cycles. During the cycling, the moisture can be pulled to the surface and cause clumping. Clumping can also be caused by static electricity if too dry or the powder has limited graphite content. You can break up the clumps before metering and they shouldn’t be a problem. This will not affect the powder performance, so your product is fine. Accurate 1680 labels are designed in Pink. As a side note, specification for testing powder is at 70° F and 60% humidity.

Shelf Life and Packaging Dates

Q: Does powder ever get to old to use and what identifying marks does your company put on the canister for when it is made, You have helped me out a while ago when I asked about keeping my cowboy shooting under 950 fps and it works great less stress on the hand and the recoil is very minimum. — R.B.

Lab Answer: On one pound bottles, the number is on the corner in a silver box. If the powder was poured today, it would read 012815 followed by a lot number. The whole number would look something like 012815749. Eight pound bottles have a sticker on the bottom with an obvious date code. The lot number appears above the date.

Western Powders Blog SAAMI Storage

Permalink - Articles, Reloading, Tech Tip 3 Comments »
August 16th, 2025

Reloading Powder Grain Shapes — What You Need to Know

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

POWDER GRAIN SHAPES — What You Need to Know

The shape of powder grains has a profound effect on the performance of the powder charge, as it concerns both pressure and velocity. There are multiple powder shapes including flake, ball, and extruded or “stick” (both solid and perforated).

So how does powder grain shape affect pressure and muzzle velocity?
In general, it can be said that powder that burns progressively achieves a desired muzzle velocity at lower maximum pressure than a powder that burns neutrally, not to mention a degressive powder. As grain size increases, the maximum pressure moves towards the muzzle, also increasing muzzle blast. Muzzle velocity and pressure can be adjusted by means of the amount of powder or loading density, i.e. the relationship between the powder mass and the volume available to it. As the loading density increases, maximum pressure grows.

All Vihtavuori reloading powders are of the cylindrical, single-perforated extruded stick type. The differences in burning rate between the powders depend on the size of the grain, the wall thickness of the cylinder, the surface coating and the composition. Cylindrical extruded powders can also have multi-perforated grains. The most common types are the 7- and 19-perforated varieties. A multi-perforated powder grain is naturally of a much larger size than one with a single perforation, and is typically used for large caliber ammunition.

Other types of powder grain shapes include sphere or ball, and flake. The ball grains are typically used in automatic firearms but also in rifles and handguns. The ball grain is less costly to produce, as it is not pressed into shape like cylindrical grains. Flake shaped grains are typically used in shotgun loadings.

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

Web thickness in gunpowder terminology means the minimum distance that the combustion zones can travel within the powder grain without encountering each other. In spherical powders, this distance is the diameter of the “ball”; in flake powder it is the thickness of the flake; and in multi-perforated extruded powders it is the minimum distance (i.e. wall thickness) between the perforations.

The burning rate of powder composed of grains without any perforations or surface treatment is related to the surface area of the grain available for burning at any given pressure level. The change in the surface area that is burning during combustion is described by a so-called form function. If the surface area increases, the form function does likewise and its behavior is termed progressive. If the form function decreases, its behavior is said to be degressive. If the flame area remains constant throughout the combustion process, we describe it as “neutral” behavior.

The cylindrical, perforated powders are progressive; the burning rate increases as the surface area increases, and the pressure builds up slower, increasing until it reaches its peak and then collapses. Flake and ball grains are degressive; the total powder surface area and pressure are at their peak at ignition, decreasing as the combustion progresses.

Learn More with FREE Vihtavuori Reloading APP »

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders


This article originally appeared on the Vihtavuori Website.

Permalink - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
June 24th, 2025

Powder Burn Rate Comparison Table — Download HERE

Hodgdon IMR Winchester Burn Rate Powder speed table relative table chart

Among AccurateShooter.com’s most-visited web pages have been powder burn rate reference guides ranking powders from fastest to slowest. Here is a new, updated version of the Powder Burn Rate Table. Compiled by Hodgdon Powder Co., this Burn Rate Chart displays the relative burn rates of 176 different powders. Shown below is the latest table, released by Hodgdon in July 2024.

You’ll want to download this Powder Burn Rate Chart PDF. This 176-entry comparison table provides vital information for hand-loaders — with tested burn-rates. Note — this invaluable chart is not limited to Hodgdon and IMR propellants. This burn rate chart includes powders from eight major powder-makers: Accurate, Alliant, Hodgdon, IMR, Norma, Ramshot (Western), Vihtavuori, and Winchester.

This chart (July 2024 version) provides useful information for all hand-loaders. When doing load development, and testing one powder versus another, it’s generally wise to choose propellants that share the same relative burn rate, as least for starters.

NOTE: Hodgdon powders are red, IMR powders are yellow, Winchester powders are blue, Accurate powders are gray, and Ramshot powders are orange. Powders from Alliant, Norma, and Vihtavuori appear on the chart with white background. DOWNLOAD Burn Rate Chart HERE as PDF.


Latest POWDER BURN RATE TABLE from HODGDON/IMR

Hodgdon IMR Winchester Burn Rate Powder speed table relative table chart

CLICK HERE to Download Chart as PDF File

Permalink - Articles, Reloading, Tech Tip 1 Comment »
April 20th, 2025

Sunday GunDay: Radical 30BR Chassis Rifle by Shelley Davidson

Shelly Davidson Tinker Toy 30 BR

Editor’s NOTE: Shelley Davidson passed away in 2008 after a courageous battle with cancer. He was one of the great innovators in benchrest rifle design. This article, written before Shelley died, showcases Shelley’s creative talents at their best. His “Tinker Toy” design will always be a tribute to Shelley’s fabricating skills and imagination.


Shelley Davidson — a brilliant innovator. R.I.P. Shelley — you will not be forgotten.

Shelley Davidson’s peers called his radical rifle the “Tinker Toy” gun. We call it revolutionary. Even now, 14 years after its creation, there’s nothing quite like it. This innovative, skeleton design threw conventional wisdom to the winds. Shelley readily concedes he “broke the rules” of benchrest rifle building. But this was inspired rule-breaking, because Davidson’s rifle shot like a house on fire. The Tinker Toy gun won its first matches, both for Score AND for Group. And this rifle also delivered many “zero groups” in Gene Begg’s Texas Tunnel. Hats off to Shelley for conceiving and building a truly radical rifle that was also wicked accurate and successful in competition.

tinker toy davidson 20 BR benchrest rifle

Tinker Toy 30 BR — Radical As It Gets

Report by Shelley Davidson
Although I’m not big on naming rifles, my shooting buddies have christened the gun “Tinker Toy.” I can live with that as it does kind of look as if it was made with a Tinker Toy set.

Origins of the Project
This project began with some wild ideas I had in the fall of 2006 about using magnets to tune a barrel. My idea was to use one magnet on the barrel and another on the stock so they pushed against each other to counter gravity-induced barrel sag (and possibly) tame barrel vibration in a beneficial manner. The only way to test these ideas was to build the device and mount it on a gun. That meant I had to build a new rifle because there was no place to mount a magnet on the stock of a conventional benchrest rig. I had a Kelbly-stocked heavy varmint stock with a Michael Kavanaugh paint job on it. I didn’t think Kav would ever forgive me if I started drilling holes in one of his works of art. My light varmint was in a carbon fiber Scoville stock that costs about a grand. Drilling into the Scoville for an experiment just smacked of bad judgment. So, the magnet thing was my first motivation for designing a new stock. As long as I was building from scratch I decided to offset the barrel and action 0.75″ to the right to counteract the spin/torque from the bullet.

Although there’s nothing new here, my second motivation was to build a 30BR that could shoot in the 10.5 lb light varmint class in NBRSA. The magnetic tuner will automatically make this gun illegal in the IBS. The IBS has declared all barrel attachments un-safe and have outlawed them. I personally feel that the IBS really outlawed all barrel attachments to prevent experimentation and innovation. But at least we have NBRSA matches.

Designing the New Gun — Thinking “Outside the Box”
Once I’d decided to build a lightweight stock that could support experimental devices out near the muzzle, I started drawing up some rough plans. I also took a trip to Jerry Stiller’s shop in Wylie, Texas for a brainstorming session with Jerry, the maker of Viper and other Benchrest actions. Jerry is a school-trained mechanical engineer and thinks differently than I do. I came away from Stiller’s shop with my design roughed out and sketched on paper. The design violated several covenants of conventional wisdom for building competition BR rifles. For instance, two-piece stocks stress the action. Stress reduction is why most BR rifles are glued into the stock. Another myth is that metal stocks vibrate too much so wood or foam-filled fiberglass or carbon fiber are used.

Tinker Toy Rifle DESIGN FEATURES

Shelly Davidson’s Rifle was so innovative, that almost every feature, except the bare action, is very different than you’ll find on most Benchrest rigs. Accordingly we felt it would be useful to isolate and describe the key design features, from stem to stern. Click thumbnails to view FULL-SIZE PHOTOS.

Front Bracket with Magnetic Tuner
The tuner consists of one rare earth magnet attached to the stock and another attached to a barrel sleeve with the magnets oriented so as to make the magnetic force repel each other. The purpose is to counter “barrel droop” and, hopefully, dampen barrel vibration. The lower magnet is carried on a threaded shaft (with lock ring), allowing the magnet to be raised up and down to adjust the “up push” on the barrel.

Tubular Fore-Arm Supported by Brackets
Three brackets support two tubes, one on either side of the barrel. The rear-most bracket is sandwiched between the barrel and the action. Four inches forward (max distance allowed for barrel blocks) a second bracket grips the barrel. Near the muzzle a third bracket secures the ends of the tubes and holds the magnetic tuner. To allow barrel offset, the left tube is 1″ diameter tube while the right tube is 5/8″ diameter.

Offset Barrel
The rifle rests on a 3″ wide plate attached to the underside of the two fore-end tubes. With the plate centered in the front sandbag, the barreled action is actually offset 0.75″ to the right (looking forward from the breech). The purpose of this offset is to keep more weight on the right side to counter the tendency of the rifle to torque counter-clockwise. Two different diameter tubes allow for the built-in offset.

Floating Action without Sub-Support or Bedding
On the Tinker Toy gun, the action serves as a load-bearing assembly, holding the barrel in the front, and the skeleton buttstock (or “keel”) in the rear. Shelley was told that accuracy would suffer if you stressed a benchrest action in this manner but that proved untrue. It is a very simple solution to building a rifle, and it eliminates the need to bed the action. The forearm attaches to the action via a bracket installed like a recoil lug.

Skeleton Rear “Keel” Affixed Directly to Action
Davidson’s Tinker Toy does not have a conventional rear buttstock. Instead there is low-profile, v-shaped metal “keel”, as Davidson calls it, that rides the rear bag. The keel is supported by a tubular backbone that attaches at the rear of the Diamondback action. At the butt end is an aluminum plate covered with bubble wrap that serves as a butt pad. The skeletonized rear section helps the rifle maintain a very low center of gravity.

Locked Scope with External Windage and Elevation Adjustment
Shelley ran an older Leupold 36X Benchrest Scope with front-adjusting objective. To eliminate slop or loose tolerances in the erector mechanism that could cause changes in point of impact, the internals have been locked up by Jackie Schmidt. To move the cross-hairs relative to the bore axis, Shelley has a special Jewell/Foster rear ring that allows a limited amount of lateral and vertical movement of the entire scope body.

TINKER TOY SPECIFICATIONS

Action: Stiller SS Diamondback Drop-Port (1/2″ short), with .308 Bolt Face.
Barrel: Shilen .308 caliber, 17-twist, HV.
Chambering: 30BR, .330″ neck, Pacific Tool & Gauge Robinett Reamer.
Stock: Davidson Custom Tubular Stock with 0.75″ Offset Barreled Action.
Tube Construction: 6061 Aluminum, 1″ diameter (left), 5/8″ diameter (right).
Load: H4198 powder and 118gr Ronnie Cheek bullets. Loaded to 2980 fps.
Trigger: Jewell, 2 ounce BR.
Tuner: Custom, Adjustable with Opposing Magnets.
Optics: Leupold 36X (locked by J. Schmidt).
Rings: Jewell Foster External Adjusting Rings.

Stiller Diamondback Action and Shilen 17-Twist Barrel
I had wanted to use an aluminum Stiller Cobra drop port with a 6mmBR bolt face but Jerry had none in stock and he estimated it would be a year before one was available. Although I’ve waited for up to a year for an action in the past, I wanted to build this rifle during the fall of 2006 while the weather was pleasant enough to work in my unheated and un-air-conditioned garage shop. Jerry did have a 1/2″ short stainless steel Diamondback in stock so I purchased it even though it would add 3 ounces to the gun compared to the aluminum Cobra. Three ounces is a lot of weight when you’re working with a 10.5-lb limit. I had a heavy varmint contour Shilen 17-twist barrel that would work nicely and I had a Jewell trigger on a rifle that I wasn’t using at the time. I also decided to use my Leupold 36X (locked-up by Jackie Schmidt) with the Jewell/Foster adjustable rings.

Building the Tube Fore-Arm and Brackets
I took a wild guess as to tubing thickness and settled on .035″ for the 1″ left fore-arm tube and .058″ for the 5/8″ right fore-arm tube. All of the flat stock and tubes are 6061 Aluminum. I did the lathe work and the mill work and every evening I’d put the parts together and think about the proper way to proceed.

tube benchrest rifle

When the parts were mostly made, I started thinking that this was a truly ugly rifle. I thought about painting it but that wasn’t a good option as many of the parts are designed to slide over others and glue together. Anodizing was the best answer so while looking on the Internet for local anodizing shops I Googled “Home Anodizing”. Sure enough there were a few sites that told about how to anodize at home. I picked up some battery acid from NAPA Auto Supply, some Rit Clothes Dye from Wal-Mart, and a bunch of distilled water from the grocery store. Using an old battery charger as my dc power supply I started anodizing and dying the eighteen parts that went into the stock. Although I had to strip and re-anodize some of the parts, the work turned out acceptable.

Putting it All Together–Lug-Mounting the Fore-Arm and Lots of Epoxy
The barrel contour had to be modified to work with the stock which attaches by way of a rear plate which mounts like a recoil lug and a plate that ties the barrel and the stock tubes together 4″ forward of the bolt face. The four-inch maximum distance is a NBRSA rule concerning barrel blocks.

Davidson Benchrest 30BR

Davidson 30BR group targetThe recoil lug-style stock mount is probably the only truly innovative thing I did other than the opposing-magnet tuner. Basically, the rear bracket is sandwiched between the receiver face and the barrel shoulder–positioned where a conventional recoil lug would go. I also added a brass ring (visible in photo) between the anodized bracket and the barrel. This was done to distribute loads over a wider surface area. (I was concerned that the bracket material was fairly soft and I didn’t want to crush it as I torqued the barrel in place.) After fitting the barrel and plates I glued the entire gun together using epoxy and various LocTite adhesives. The rest of the parts were assembled but I did not Loctite the scope bases since I thought I’d be disassembling the rifle for re-work after the first trials. That came back to bite me during later testing when the gun started shooting erratically and I went down a couple of blind alleys before finding the loose bases.

Range Testing–Results Are Very Positive
The first range session was a real shocker. Even though the wind was up to 10mph and twitchy, the rifle showed promise from the very first shot. I really didn’t expect that kind of performance without, at least, some rework. After sighting in, I shot five, 5-shot groups that, when averaged together, measured .223″. That’s good enough to win some benchrest group matches. But I wasn’t finished with the gun yet–I still wanted to try out my magnetic tuner concept.

Magnetic Benchrest Tuner Davidson

The Magnetic Tuner
Next, I built the magnetic tuner. The tuner consists of one rare earth magnet attached to the stock and another attached to a barrel sleeve with the magnets oriented so the magnetic forces repel each other. In order to test the magnets and to determine if the rifle really shot as well as it seemed to, I took it to Gene Beggs’s shooting tunnel in Odessa, Texas. I spent two days at the tunnel testing loads and then installed the magnetic tuner. The gun shoots well with the magnets and shoots well without them. I suppose I can’t make any claims as to how much, if any, improvement the magnets make. Gene said that my gun was the most accurate rifle to be tested at his one-year-old shooting facility: “Shelley Davidson brought one of the most unusual rifles I had ever seen; he called it his ‘Tube Gun.’ And boy, did it ever shoot! It still holds the record in the tunnel as the rifle that shot more zeros than any other to date.” I definitely recommend Gene’s facility for testing and refining shooting techniques and loads.

Competition — Tinker Toy Won Both Score and Group Matches

Finally the big day arrived when I’d shoot the first match with my new gun. The North Texas Shooters Association was holding its first club match of the 2007 season. At the Denton, Texas matches we shoot a Score Match in the morning and a Group Match in the afternoon. The March event was at 100 yards and the April match will be at 200 yards and so on alternating throughout the benchrest season.

Davidson tube BR rifle Score MatchMatch One–Tinker Toy Wins Score with a 250 – 17X
Since the gun is chambered in 30BR and that chambering is almost immune to tuning woes, I preloaded 130 rounds with H4198 powder and 118gr Cheek bullets. I used my SEB front rest and rear bag which are made by Sebastian Lambang in Indonesia. Everything came together, and Tinker Toy demonstrated that the accuracy it showed in the tunnel was no fluke. The gun shot great and I won the morning match with a 250, 17X. The day was quite windy and the next best shooter scored a 250, 15X. So I’d chalked up my first win.

Match Two–Tinker Toy Wins Group with a .2282″ Agg
Tinker Toy won the afternoon group match I entered with a five-group Aggregate of .2282″. (The second place score was .2568″.) My groups were .149″, .197″, .243″, .302″ (oops), and .250″. You know how some folks say a 30BR can’t be competitive with a PPC? Well that .2282″ Agg won’t break any records, but it is good enough to win some regional registered BR matches. So this rifle has demonstrated an ability to win in both Score and Group matches. Obviously I have a very good Shilen barrel, great Cheek bullets and the rest of the components are doing their jobs as well. But, the stock is also working well.

Score Shooting vs. Group Shooting–The Rules
In a score match, the shooter shoots one bullet at each of five record targets, which are clustered on one target sheet. The Aggregate score of five of these targets determines the winner. If the shooter touches the 10 ring on all of his 25 targets he can score a “clean” 250 score. Usually there will be more than one shooter who scores a 250 so the winner is determined by the X-count. The 1/2″ 10-point ring has a 1/16″ dot in its center. Touching the X dot adds to the shooters X count. In short-range group matches, the shooter must try to put five bullets through the same hole. At each distance (100 or 200), five, 5-shot matches are scored, the group sizes are added together (MOA equivalent at 200) and the total is divided by five to arrive at an Aggregate score.

Permalink Competition, Gear Review, Gunsmithing, Tech Tip No Comments »
February 19th, 2025

Basics of Reloading Powder Grain Shapes and Properties

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

POWDER GRAIN SHAPES — What You Need to Know

The shape of powder grains has a profound effect on the performance of the powder charge, as it concerns both pressure and velocity. There are multiple powder shapes including flake, ball, and extruded or “stick” (both solid and perforated).

So how does powder grain shape affect pressure and muzzle velocity?
In general, it can be said that powder that burns progressively achieves a desired muzzle velocity at lower maximum pressure than a powder that burns neutrally, not to mention a degressive powder. As grain size increases, the maximum pressure moves towards the muzzle, also increasing muzzle blast. Muzzle velocity and pressure can be adjusted by means of the amount of powder or loading density, i.e. the relationship between the powder mass and the volume available to it. As the loading density increases, maximum pressure grows.

All Vihtavuori reloading powders are of the cylindrical, single-perforated extruded stick type. The differences in burning rate between the powders depend on the size of the grain, the wall thickness of the cylinder, the surface coating and the composition. Cylindrical extruded powders can also have multi-perforated grains. The most common types are the 7- and 19-perforated varieties. A multi-perforated powder grain is naturally of a much larger size than one with a single perforation, and is typically used for large caliber ammunition.

Other types of powder grain shapes include sphere or ball, and flake. The ball grains are typically used in automatic firearms but also in rifles and handguns. The ball grain is less costly to produce, as it is not pressed into shape like cylindrical grains. Flake shaped grains are typically used in shotgun loadings.

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

Web thickness in gunpowder terminology means the minimum distance that the combustion zones can travel within the powder grain without encountering each other. In spherical powders, this distance is the diameter of the “ball”; in flake powder it is the thickness of the flake; and in multi-perforated extruded powders it is the minimum distance (i.e. wall thickness) between the perforations.

The burning rate of powder composed of grains without any perforations or surface treatment is related to the surface area of the grain available for burning at any given pressure level. The change in the surface area that is burning during combustion is described by a so-called form function. If the surface area increases, the form function does likewise and its behavior is termed progressive. If the form function decreases, its behavior is said to be degressive. If the flame area remains constant throughout the combustion process, we describe it as “neutral” behavior.

The cylindrical, perforated powders are progressive; the burning rate increases as the surface area increases, and the pressure builds up slower, increasing until it reaches its peak and then collapses. Flake and ball grains are degressive; the total powder surface area and pressure are at their peak at ignition, decreasing as the combustion progresses.

Learn More with FREE Vihtavuori Reloading APP »

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders


This article originally appeared on the Vihtavuori Website.

Permalink Bullets, Brass, Ammo, Reloading No Comments »
March 7th, 2024

Reloading Powder Shape Properties — What You Need to Know

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

POWDER GRAIN SHAPES — What You Need to Know

The shape of powder grains has a profound effect on the performance of the powder charge, as it concerns both pressure and velocity. There are multiple powder shapes including flake, ball, and extruded or “stick” (both solid and perforated).

So how does powder grain shape affect pressure and muzzle velocity?
In general, it can be said that powder that burns progressively achieves a desired muzzle velocity at lower maximum pressure than a powder that burns neutrally, not to mention a degressive powder. As grain size increases, the maximum pressure moves towards the muzzle, also increasing muzzle blast. Muzzle velocity and pressure can be adjusted by means of the amount of powder or loading density, i.e. the relationship between the powder mass and the volume available to it. As the loading density increases, maximum pressure grows.

All Vihtavuori reloading powders are of the cylindrical, single-perforated extruded stick type. The differences in burning rate between the powders depend on the size of the grain, the wall thickness of the cylinder, the surface coating and the composition. Cylindrical extruded powders can also have multi-perforated grains. The most common types are the 7- and 19-perforated varieties. A multi-perforated powder grain is naturally of a much larger size than one with a single perforation, and is typically used for large caliber ammunition.

Other types of powder grain shapes include sphere or ball, and flake. The ball grains are typically used in automatic firearms but also in rifles and handguns. The ball grain is less costly to produce, as it is not pressed into shape like cylindrical grains. Flake shaped grains are typically used in shotgun loadings.

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

Web thickness in gunpowder terminology means the minimum distance that the combustion zones can travel within the powder grain without encountering each other. In spherical powders, this distance is the diameter of the “ball”; in flake powder it is the thickness of the flake; and in multi-perforated extruded powders it is the minimum distance (i.e. wall thickness) between the perforations.

The burning rate of powder composed of grains without any perforations or surface treatment is related to the surface area of the grain available for burning at any given pressure level. The change in the surface area that is burning during combustion is described by a so-called form function. If the surface area increases, the form function does likewise and its behavior is termed progressive. If the form function decreases, its behavior is said to be degressive. If the flame area remains constant throughout the combustion process, we describe it as “neutral” behavior.

The cylindrical, perforated powders are progressive; the burning rate increases as the surface area increases, and the pressure builds up slower, increasing until it reaches its peak and then collapses. Flake and ball grains are degressive; the total powder surface area and pressure are at their peak at ignition, decreasing as the combustion progresses.

Learn More with FREE Vihtavuori Reloading APP »

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders


This article originally appeared on the Vihtavuori Website.

Permalink - Articles, Bullets, Brass, Ammo, Reloading No Comments »
January 6th, 2024

Long-Term Powder Storage — Important Guidelines to Follow

Western Powders Blog SAAMI Storage

SUMMARY: Powder can have a very long shelf life. You need to watch for changes in smell and color. A reddish tinge, almost like rust on the powder, is a bad sign, as is a foul odor, not to be confused with a normal chemical smell. Either of these signs indicate it is time to dispose of your powder by means other than shooting.

Ever wondered about the stability of the propellants in your reloading room? There are some important things you should know about powder storage, to ensure consistent powder performance and safety. Western Powders (which has been acquired by Hodgdon) published an informative Q & A series entitled Dear Labby: Questions for our Ballistics Lab . Here are some excerpts that pertain to powder storage and shelf life. Worried that your powder may be too old? Western’s experts explain how to check your propellants for warning signs.

Proper Powder Storage

Q: I live in southern Arizona where it is very hot. I am told powders will become unstable if stored in an area not air-conditioned. My wife says no powder or primers in the house. Can powder be stored in a refrigerator? What about using a fireproof safe? I would appreciate your ideas. — M.C.

Lab Answer: SAAMI guidelines are pretty clear on issues of storage. They recommend storing smokeless powder in containers that will not allow pressure to build if the powder is ignited — ruling out gun safes and refrigerators.

CLICK HERE to Read SAAMI Guidelines for Powder Storage (PDF)

In their original containers, the lifespan of smokeless powders is quite long, even in hot, arid climates. In fact the lifespan is typically longer than the average handloader would need to store them. Stored safely in a garage or outbuilding, your powder should last years. If you see the powder developing a reddish tint, or giving off a foul odor, it is time to discard it.

Clumps in Powder Container

Q: I ordered some of your Accurate 1680 powder back about in December. I just now opened it … and it is full of clumps. My knowledge tells me that means moisture. Am I wrong? I just now broke the seal and it has been stored in a ammo can with desiccant packs around it and a dehumidifier running 14-16 hours a day. I can’t imagine this being my fault, if this does indicate moisture. I don’t know if the pink part on the label is suppose to be red or not, but it is definitely pink, so if it was red I am wondering if I was shipped an old container? I hope that this isn’t bad and I am stuck with it…

Lab Answer: All powder contains a certain amount of moisture. When the powder is stored or during shipping, it can go through temperature cycles. During the cycling, the moisture can be pulled to the surface and cause clumping. Clumping can also be caused by static electricity if too dry or the powder has limited graphite content. You can break up the clumps before metering and they shouldn’t be a problem. This will not affect the powder performance, so your product is fine. Accurate 1680 labels are designed in Pink. As a side note, specification for testing powder is at 70° F and 60% humidity.

Shelf Life and Packaging Dates

Q: Does powder ever get to old to use and what identifying marks does your company put on the canister for when it is made, You have helped me out a while ago when I asked about keeping my cowboy shooting under 950 fps and it works great less stress on the hand and the recoil is very minimum. — R.B.

Lab Answer: On one pound bottles, the number is on the corner in a silver box. If the powder was poured today, it would read 012815 followed by a lot number. The whole number would look something like 012815749. Eight pound bottles have a sticker on the bottom with an obvious date code. The lot number appears above the date.

Western Powders Blog SAAMI Storage

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July 6th, 2023

Powder Valley Launches Enhanced, Full-Featured Website

powder valley inc. reloading powder primers website store new updated supplies

Powder Valley, a leading distributor of reloading supplies, is pleased to announce the launch of a major update and enhancement to its PowderValley.com website. The enhanced website now has a completely updated look, improved search and browse features, along with a streamlined checkout experience. The updated website is also mobile-friendly so it works great with smartphones and mobile devices. And right now the Powder Valley website features special discounts, with some items up to 50% Off. For big savings, click the Weekly Deals tag on the home page.

There are convenient, one-click product category links for:

Ammunition
Smokeless Powder
Primers
Bullets

Reloading Brass
Reloading Tools
Reloading Manuals
Shotshell Ammunition

Muzzleloading
Shooting Supplies
Swag
Gun Safes & Storage

“We’re excited to provide our customers with a new website that is fast, easy to navigate, and helps them make an informed buying decision” said Bill Clinton, CEO of Powder Valley. “The new website is the first step in a series of strategic changes at Powder Valley which will improve our ability to implement significant improvement in how we serve customers, from enhanced product information to increased breadth and depth of our product offering.”

To learn more about Powder Valley and its full lineup of reloading supplies, visit PowderValley.com. On the updated website, as you scroll down the home page, you’ll see convenient major feature categories for:

1. Sales and Clearance | 2. New Arrivals | 3. Popular Products

powder valley inc. reloading powder primers website store new updated supplies

About Powder Valley
Powder Valley began in 1984 as Dexter Automotive, the first master distributor of Accurate brand powder. In 2000, Bryan and Noel Richardson purchased the company and moved operations to Winfield, Kansas. Since then Powder Valley has become the single largest distributor of canister powder in the USA, stocking nearly every brand of Smokeless and Black Powder offered in the nation. Powder brands include Hodgdon, IMR, Vihtavuori, Alliant, Ramshot, Winchester, Hornady, Shooters World, Goex, Schuetzen, Swiss and more, along with an ever-expanding offering of bullets, brass, wads, shot, gun care items, and reloading equipment. Powder Valley also carries a wide selection of rifle, pistol, and shotgun primers.

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December 12th, 2022

Reloading Powder Storage — Important Guidelines to Follow

Western Powders Blog SAAMI Storage

SUMMARY: Powder can have a very long shelf life. You need to watch for changes in smell and color. A reddish tinge, almost like rust on the powder, is a bad sign, as is a foul odor, not to be confused with a normal chemical smell. Either of these signs indicate it is time to dispose of your powder by means other than shooting.

Ever wondered about the stability of the propellants in your reloading room? There are some important things you should know about powder storage, to ensure consistent powder performance and safety. Western Powders (which has been acquired by Hodgdon) published an informative Q & A series entitled Dear Labby: Questions for our Ballistics Lab . Here are some excerpts that pertain to powder storage and shelf life. Worried that your powder may be too old? Western’s experts explain how to check your propellants for warning signs.

Proper Powder Storage

Q: I live in southern Arizona where it is very hot. I am told powders will become unstable if stored in an area not air-conditioned. My wife says no powder or primers in the house. Can powder be stored in a refrigerator? What about using a fireproof safe? I would appreciate your ideas. — M.C.

Lab Answer: SAAMI guidelines are pretty clear on issues of storage. They recommend storing smokeless powder in containers that will not allow pressure to build if the powder is ignited — ruling out gun safes and refrigerators.

CLICK HERE to Read SAAMI Guidelines for Powder Storage (PDF)

In their original containers, the lifespan of smokeless powders is quite long, even in hot, arid climates. In fact the lifespan is typically longer than the average handloader would need to store them. Stored safely in a garage or outbuilding, your powder should last years. If you see the powder developing a reddish tint, or giving off a foul odor, it is time to discard it.

Clumps in Powder Container

Q: I ordered some of your Accurate 1680 powder back about in December. I just now opened it … and it is full of clumps. My knowledge tells me that means moisture. Am I wrong? I just now broke the seal and it has been stored in a ammo can with desiccant packs around it and a dehumidifier running 14-16 hours a day. I can’t imagine this being my fault, if this does indicate moisture. I don’t know if the pink part on the label is suppose to be red or not, but it is definitely pink, so if it was red I am wondering if I was shipped an old container? I hope that this isn’t bad and I am stuck with it…

Lab Answer: All powder contains a certain amount of moisture. When the powder is stored or during shipping, it can go through temperature cycles. During the cycling, the moisture can be pulled to the surface and cause clumping. Clumping can also be caused by static electricity if too dry or the powder has limited graphite content. You can break up the clumps before metering and they shouldn’t be a problem. This will not affect the powder performance, so your product is fine. Accurate 1680 labels are designed in Pink. As a side note, specification for testing powder is at 70° F and 60% humidity.

Shelf Life and Packaging Dates

Q: Does powder ever get to old to use and what identifying marks does your company put on the canister for when it is made, You have helped me out a while ago when I asked about keeping my cowboy shooting under 950 fps and it works great less stress on the hand and the recoil is very minimum. — R.B.

Lab Answer: On one pound bottles, the number is on the corner in a silver box. If the powder was poured today, it would read 012815 followed by a lot number. The whole number would look something like 012815749. Eight pound bottles have a sticker on the bottom with an obvious date code. The lot number appears above the date.

Western Powders Blog SAAMI Storage

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August 21st, 2022

Hand-Loading Basics Covered by Hodgdon Reloading Videos

Hodgdon Reloading Center Video

Hodgdon Reloading Center VideoHodgdon Powder Company (Hodgdon) offers a series of professionally-produced, “how-to” instructional videos through its online Reloading Data Center. These 3.5-minute videos present rifle, pistol, and shotshell reloading basics in an easy-to-understand, step-by-step format. These mobile-friendly, informative videos can also be viewed on a smart phone or tablet.

To watch the reloading videos go to the Reloading Data Center at hodgdon.com. With your cursor placed to the right/left of the displayed video, click to switch between pistol, rifle, and shotgun videos. Or, for your convenience, we have embedded the Rifle and Pistol videos here. Just click to watch!

Click to Watch Hodgdon Rifle Reloading Video:

Click to Watch Hodgdon Pistol Reloading Video:

In addition to these videos, Hodgdon’s Reloading Data Center (RDC) provides a wealth of information on Hodgdon®, IMR®, and Winchester® propellants. Along with reliable load data, you’ll find explanations of reloading basics, safety procedures, plus answers to frequently asked questions (FAQ).

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