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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 »
October 21st, 2023

Humidity Changes Can Alter Powder Burn Rates and Performance

Tech Tip Norma Powder gunpowder moisture temperature humidity

The leaves are falling, and that means the rainy season will soon begin in many areas of the country. With rain comes increased moisture in the air, i.e. increased humidity. And that, in turn, can affect how your powders perform by altering their burn rates.

Most shooters realize that significant changes in temperature will alter how powders perform. That’s why you want to keep your loaded ammo out of the hot sun, and keep rounds out of a hot chamber until you’re ready to fire. But there are other factors to be considered — HUMIDITY for one. This article explains why and how humidity can affect powder burn rates and performance.

We’ve all heard the old adage: “Keep your powder dry”. Well, tests by Norma have demonstrated that even normal environmental differences in humidity can affect the way powders burn, at least over the long term. In the Norma Reloading Manual, Sven-Eric Johansson, head of ballistics at Nexplo/Bofors, presents a very important discussion of water vapor absorption by powder. Johansson demonstrates that the same powder will burn at different rates depending on water content.

Powders Leave the Factory with 0.5 to 1.0% Water Content
Johansson explains that, as manufactured, most powders contain 0.5 to 1% of water by weight. (The relative humidity is “equilibrated” at 40-50% during the manufacturing process to maintain this 0.5-1% moisture content). Importantly, Johansson notes that powder exposed to moist air for a long time will absorb water, causing it to burn at a slower rate. On the other hand, long-term storage in a very dry environment reduces powder moisture content, so the powder burns at a faster rate. In addition, Johansson found that single-base powders are MORE sensitive to relative humidity than are double-base powders (which contain nitroglycerine).

Tests Show Burn Rates Vary with Water Content
In his review of the Norma Manual, Fred Barker notes: “Johansson gives twelve (eye-opening) plots of the velocities and pressures obtained on firing several popular cartridges with dehydrated, normal and hydrated Norma powders (from #200 to MRP). He also gives results on loaded .30-06 and .38 Special cartridges stored for 663 to 683 days in relative humidities of 20% and 86%. So Johansson’s advice is to keep powders tightly capped in their factory containers, and to minimize their exposure to dry or humid air.”

Confirming Johansson’s findings that storage conditions can alter burn rates, Barker observes: “I have about 10 pounds of WWII 4831 powder that has been stored in dry (about 20% RH) Colorado air for more than 60 years. It now burns about like IMR 3031.”

What does this teach us? First, all powders start out with a small, but chemically important, amount of water content. Second, a powder’s water content can change over time, depending on where and how the powder is stored. Third, the water content of your powder DOES make a difference in how it burns, particularly for single-base powders. For example, over a period of time, a powder used (and then recapped) in the hot, dry Southwest will probably behave differently than the same powder used in the humid Southeast.

Reloaders are advised to keep these things in mind. If you want to maintain your powders’ “as manufactured” burn rate, it is wise to head Johannson’s recommendation to keep your powders tightly capped when you’re not actually dispensing charges and avoid exposing your powder to very dry or very humid conditions. The Norma Reloading Manual is available from MidwayUSA for $24.99.

Real-World Example — “Dry” H4831sc Runs Hotter

Robert Whitley agrees that the burn rate of the powder varies with the humidity it absorbs. Robert writes: “I had an 8-lb. jug of H4831SC I kept in my detached garage (it can be humid there). 43.5-44.0 gr of this was superbly accurate with the 115 Bergers out of my 6mm Super X. I got tired of bringing it in and out of the garage to my house for reloading so I brought and kept the jug in my reloading room (a dehumidified room in my house) and after a few weeks I loaded up 43.5 gr, went to a match and it shot awful. I could not figure out what was going on until I put that load back over the chronograph and figured out it was going a good bit faster than before and the load was out of the “sweet spot” (42.5 – 43.0 gr was the max I could load and keep it accurate when it was stored in less humid air). I put the jug back in the garage for a few weeks and I now am back to loading 43.5 – 44.0 gr and it shoots great again. I have seen this with other powders too.”

If you have two jugs of the same powder, one kept in a room in your house and one somewhere else where it is drier or more humid, don’t expect the two jugs of the same lot of powder to chrono the same with the same charge weights unless and until they are both stored long enough in the same place to equalize again.

Permalink - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip 2 Comments »
April 27th, 2023

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 »
January 15th, 2022

Changes in Humidity Can Alter Powder Burn Rates — IMPORTANT

Tech Tip Norma Powder gunpowder moisture temperature humidity

Most shooters realize that significant changes in temperature will alter how powders perform. That’s why you want to keep your loaded ammo out of the hot sun, and keep rounds out of a hot chamber until you’re ready to fire. But there are other factors to be considered — HUMIDITY for one. This article explains why and how humidity can affect powder burn rates and performance.

We’ve all heard the old adage: “Keep your powder dry”. Well, tests by Norma have demonstrated that even normal environmental differences in humidity can affect the way powders burn, at least over the long term. In the Norma Reloading Manual, Sven-Eric Johansson, head of ballistics at Nexplo/Bofors, presents a very important discussion of water vapor absorption by powder. Johansson demonstrates that the same powder will burn at different rates depending on water content.

Powders Leave the Factory with 0.5 to 1.0% Water Content
Johansson explains that, as manufactured, most powders contain 0.5 to 1% of water by weight. (The relative humidity is “equilibrated” at 40-50% during the manufacturing process to maintain this 0.5-1% moisture content). Importantly, Johansson notes that powder exposed to moist air for a long time will absorb water, causing it to burn at a slower rate. On the other hand, long-term storage in a very dry environment reduces powder moisture content, so the powder burns at a faster rate. In addition, Johansson found that single-base powders are MORE sensitive to relative humidity than are double-base powders (which contain nitroglycerine).

Tests Show Burn Rates Vary with Water Content
In his review of the Norma Manual, Fred Barker notes: “Johansson gives twelve (eye-opening) plots of the velocities and pressures obtained on firing several popular cartridges with dehydrated, normal and hydrated Norma powders (from #200 to MRP). He also gives results on loaded .30-06 and .38 Special cartridges stored for 663 to 683 days in relative humidities of 20% and 86%. So Johansson’s advice is to keep powders tightly capped in their factory containers, and to minimize their exposure to dry or humid air.”

Confirming Johansson’s findings that storage conditions can alter burn rates, Barker observes: “I have about 10 pounds of WWII 4831 powder that has been stored in dry (about 20% RH) Colorado air for more than 60 years. It now burns about like IMR 3031.”

What does this teach us? First, all powders start out with a small, but chemically important, amount of water content. Second, a powder’s water content can change over time, depending on where and how the powder is stored. Third, the water content of your powder DOES make a difference in how it burns, particularly for single-base powders. For example, over a period of time, a powder used (and then recapped) in the hot, dry Southwest will probably behave differently than the same powder used in the humid Southeast.

Reloaders are advised to keep these things in mind. If you want to maintain your powders’ “as manufactured” burn rate, it is wise to head Johannson’s recommendation to keep your powders tightly capped when you’re not actually dispensing charges and avoid exposing your powder to very dry or very humid conditions. The Norma Reloading Manual is available from MidwayUSA for $24.99.

Real-World Example — “Dry” H4831sc Runs Hotter

Robert Whitley agrees that the burn rate of the powder varies with the humidity it absorbs. Robert writes: “I had an 8-lb. jug of H4831SC I kept in my detached garage (it can be humid there). 43.5-44.0 gr of this was superbly accurate with the 115 Bergers out of my 6mm Super X. I got tired of bringing it in and out of the garage to my house for reloading so I brought and kept the jug in my reloading room (a dehumidified room in my house) and after a few weeks I loaded up 43.5 gr, went to a match and it shot awful. I could not figure out what was going on until I put that load back over the chronograph and figured out it was going a good bit faster than before and the load was out of the “sweet spot” (42.5 – 43.0 gr was the max I could load and keep it accurate when it was stored in less humid air). I put the jug back in the garage for a few weeks and I now am back to loading 43.5 – 44.0 gr and it shoots great again. I have seen this with other powders too.”

If you have two jugs of the same powder, one kept in a room in your house and one somewhere else where it is drier or more humid, don’t expect the two jugs of the same lot of powder to chrono the same with the same charge weights unless and until they are both stored long enough in the same place to equalize again.

Permalink - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
August 24th, 2021

What You Need to Know about Powder Grain Shapes

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 »
April 28th, 2020

Vihtavuori Explains Powder Grain Shapes

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).

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.

So how does the 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.

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, Tech Tip 1 Comment »
February 2nd, 2020

How Powder Moisture Content Affects Pressure and Speed

vihtavuori vv moisture content powder propellent
This Technical Report Comes from the Vihtavuori website.

Powder Moisture Content — Did You Know?
Variations in moisture content change the burning rate of a powder and thereby chamber pressures and muzzle velocity. The moisture content of the Vihtavuori N100 and N300 series powders is usually around 1%, while the N500-series’ normal moisture content is 0.6% because of the added nitroglycerine.

So what difference does moisture content make? Here’s an example. In a test, a [Vihtavuori] powder sample was dried by heating it, losing about 0.5 % of its weight. Cartridges were then loaded with the dried powder and fired using a pressure gun. Chamber pressures and muzzle velocities produced by these special cartridges were compared to those produced by cartridges loaded with untreated powder. (The powder charge and bullet were of course the same in both sets of cartridges.)

After Powder Drying:
Pressure Increased 11% from 320 MPa to 355 MPa
Velocity Increased 2.6% from 2526 to 2592 FPS

Comparing results showed chamber pressures increased from 320 MPa to 355 MPa with the dried powder, and the muzzle velocity increased accordingly from 770 m/s to 790 m/s (2526 to 2592 FPS). And note, this is only one example, of one caliber and loading. The difference might be much higher depending on the cartridge and loading combinations.

Recommendation: Store powder below 68°F in 55-65% humidity.

What does this tell us? Well, it seems we need to forget the old saying “Keep your powder dry”! Instead, focus on proper powder storage, at a temperature below 20°C/68°F and humidity between 55 and 65%. Safe reloading everybody!

vihtavuori vv moisture content powder propellent

Tech Tip sourced by EdLongrange. We welcome reader submissions.
Permalink Reloading, Tech Tip No Comments »
March 24th, 2018

Humidity and Powder Burn Rates — What You Need to Know

Tech Tip Norma Powder gunpowder moisture temperature humidity

Most shooters realize that significant changes in temperature will alter how powders perform. That’s why you want to keep your loaded ammo out of the hot sun, and keep rounds out of a hot chamber until you’re ready to fire. But there are other factors to be considered — HUMIDITY for one. This article explains why and how humidity can affect powder burn rates and performance.

We’ve all heard the old adage: “Keep your powder dry”. Well, tests by Norma have demonstrated that even normal environmental differences in humidity can affect the way powders burn, at least over the long term. In the Norma Reloading Manual, Sven-Eric Johansson, head of ballistics at Nexplo/Bofors, presents a very important discussion of water vapor absorption by powder. Johansson demonstrates that the same powder will burn at different rates depending on water content.

Powders Leave the Factory with 0.5 to 1.0% Water Content
Johansson explains that, as manufactured, most powders contain 0.5 to 1% of water by weight. (The relative humidity is “equilibrated” at 40-50% during the manufacturing process to maintain this 0.5-1% moisture content). Importantly, Johansson notes that powder exposed to moist air for a long time will absorb water, causing it to burn at a slower rate. On the other hand, long-term storage in a very dry environment reduces powder moisture content, so the powder burns at a faster rate. In addition, Johansson found that single-base powders are MORE sensitive to relative humidity than are double-base powders (which contain nitroglycerine).

Tests Show Burn Rates Vary with Water Content
In his review of the Norma Manual, Fred Barker notes: “Johansson gives twelve (eye-opening) plots of the velocities and pressures obtained on firing several popular cartridges with dehydrated, normal and hydrated Norma powders (from #200 to MRP). He also gives results on loaded .30-06 and .38 Special cartridges stored for 663 to 683 days in relative humidities of 20% and 86%. So Johansson’s advice is to keep powders tightly capped in their factory containers, and to minimize their exposure to dry or humid air.”

Confirming Johansson’s findings that storage conditions can alter burn rates, Barker observes: “I have about 10 pounds of WWII 4831 powder that has been stored in dry (about 20% RH) Colorado air for more than 60 years. It now burns about like IMR 3031.”

What does this teach us? First, all powders start out with a small, but chemically important, amount of water content. Second, a powder’s water content can change over time, depending on where and how the powder is stored. Third, the water content of your powder DOES make a difference in how it burns, particularly for single-base powders. For example, over a period of time, a powder used (and then recapped) in the hot, dry Southwest will probably behave differently than the same powder used in the humid Southeast.

Reloaders are advised to keep these things in mind. If you want to maintain your powders’ “as manufactured” burn rate, it is wise to head Johannson’s recommendation to keep your powders tightly capped when you’re not actually dispensing charges and avoid exposing your powder to very dry or very humid conditions. The Norma Reloading Manual is available from Amazon.com.

Real-World Example — “Dry” H4831sc Runs Hotter

Robert Whitley agrees that the burn rate of the powder varies with the humidity it absorbs. Robert writes: “I had an 8-lb. jug of H4831SC I kept in my detached garage (it can be humid there). 43.5-44.0 gr of this was superbly accurate with the 115 Bergers out of my 6mm Super X. I got tired of bringing it in and out of the garage to my house for reloading so I brought and kept the jug in my reloading room (a dehumidified room in my house) and after a few weeks I loaded up 43.5 gr, went to a match and it shot awful. I could not figure out what was going on until I put that load back over the chronograph and figured out it was going a good bit faster than before and the load was out of the “sweet spot” (42.5 – 43.0 gr was the max I could load and keep it accurate when it was stored in less humid air). I put the jug back in the garage for a few weeks and I now am back to loading 43.5 – 44.0 gr and it shoots great again. I have seen this with other powders too.”

If you have two jugs of the same powder, one kept in a room in your house and one somewhere else where it is drier or more humid, don’t expect the two jugs of the same lot of powder to chrono the same with the same charge weights unless and until they are both stored long enough in the same place to equalize again.

Permalink - Articles, Reloading 12 Comments »
January 23rd, 2018

Download Latest Hodgdon IMR Relative Burn Rate Chart

Hodgdon IMR Winchester Burn Rate Powder speed table relative table chart

Hey guys, you’ll probably want to download this new Powder Burn Rate Chart issued by Hodgdon/IMR. This recently-released table includes the latest IMR powders including the Enduron series (IMR 4166, 4451, 4955, 7977), shown in green below. Please note, the chart is not limited to Hodgdon and IMR propellants. It also includes popular powders from Accurate, Alliant, Norma, Ramshot (Western), Vihtavuori, and Winchester.

This chart 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 shown in blue, IMR standard powders are shown in yellow, IMR Enduron powders are shown in green, and Winchester powder are shown in red. DOWNLOAD Chart HERE.


NEW POWDER BURN RATE TABLE from IMRPowder.com

Hodgdon IMR Winchester Burn Rate Powder speed table relative table chart

CLICK HERE to Download Chart as PDF File »

Story find by EdLongrange. We welcome reader submissions.
Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 6 Comments »
September 16th, 2016

Vihtavuori Powders Loading Information Online

vihtavuori reloading guide
Click image for Online Reloading Data. CLICK HERE for Printable PDF Reloading Guide.

Vihtavuori has updated and enhanced its reloading information, adding VV powder load recipes for many more cartridge types. Data is now online for 64 rifle cartridge types and 26 pistol cartridge types. You’ll find the updated reloading data on the Vihtavuori Website. Bookmark this link: www.vihtavuori.com/en/reloading-data/about-reloading.html.

The updated online information supplements the Vihtavuori Reloading Guide (2016 Edition) available in PDF format. The online Reloading Database has dedicated sections for Rifle Cartridges, Pistol Cartridges, and Cowboy Action. There is also a handy, FREE Reload Mobile App for iOS and Android.


Rifle Reload DATA | Handgun Reload DATA| Mobile Reload App

vihtavuori reloading guide

Rifle Reloading Data

Vihtavuori’s Rifle Reloading Database is now very comprehensive. Many of the popular modern match cartridges such as the 6.5×47 Lapua and 6.5 Creedmoor are now included, and of course you’ll find the 6mm PPC, 6mmBR, and 6XC. (There is no .284 Win or 7mm RSAUM data unfortunately.) You will find recommended load recipes for all the following cartridges:

.204 Ruger
.221 Remington Fireball
.222 Remington
.22 Hornet
.22 PPC-USA
.223 Remington
.22-250 Remington
.223 WSSM
.243 Winchester
.243 WSSM
6mm PPC-USA
6mmBR Norma
6 XC
6mm Remington
.240 Weatherby Magnum
6.5 Grendel
6.5 x 47 Lapua
6.5 Creedmoor
6,5 x 55 Swedish Mauser
6,5 x 55 Swedish Mauser/ SKAN
6.5-284 Norma
.25-06 Remington
.260 Remington
.270 Winchester
.270 WSM
.270 Weatherby Magnum
7 mm-08 Remington
7 x 57
7 x 64
7 mm Remington Magnum
7 mm WSM
7 mm RUM

7 x 57R
7 mm Weatherby Magnum
7,5 x 55 Swiss GP31
.30 Carbine
.30-30 Winchester
.300 AAC Blackout
7,62 x 39
.300 Savage
7,62 x 53R (7,62 Russian)
.308 Winchester
.30-06 Springfield
.300 Lapua Magnum
.300 Remington Ultra Magnum
.300 Winchester Magnum
.300 Weatherby Magnum
.30-.378 Weatherby Magnum
.300 H&H Magnum
.300 WSM
.303 British
8 x 57 IRS
8 x 57 IS (8 mm Mauser)
.338 Winchester Magnum
.338 Lapua Magnum
9,3 x 62
9,3 x 66 Sako
9,3 x 74R
.375 H&H Magnum
.416 Rigby
.444 Marlin
.45-70 Government
.458 Winchester Magnum
.50 Browning

Handgun Reloading Data

Likewise, VV’s Handgun Reloading Database is extensive. These pistol cartridges are covered:

.32 S&W Long N.P.
.32 S&W Long Wadcutter
.357 Remington Maximum
.357 Magnum
.357 SIG
.38 Super Lapua
.38 Super Auto
.38 Special
7 mm GJW
7 mm TCU
7 mm BR Remington
7,62 x 25 Tokarev
9 mm Luger

9 x 21
9 x 23 Winchester
.40 S&W
10 mm AUTO
.41 Remington Magnum
.44 S&W Special
.44 Remington Magnum
.45 ACP
.45 Colt
.45 Winchester Magnum
.454 Casull
.500 S&W Magnum
.50 AE

Story Tip by EdLongrange. We welcome reader submissions.
Permalink Bullets, Brass, Ammo, Reloading 4 Comments »
April 22nd, 2016

IMR® Powders introduces IMR 4955 Enduron Powder

Hodgdon IMR Enduron 4955 temperature stable powder reduced fouling

In 2015, IMR® Powder introduced a new line of powders with Enduron® Technology. These powders are designed to address several performance gaps as powder technology has advanced. Here are key features of the Enduron line of propellants:

  • Enduron powders contain an additive that drastically reduces copper fouling in the gun barrel. Copper fouling should be minimal, allowing shooters to spend more time shooting and less time cleaning a rifle to retain accuracy.
  • The new Enduron line is insensitive to temperature changes. Whether a rifle is sighted in during the heat of summer, hunted in a November snowstorm or hunting multiple locations with drastic temperature swings, point of impact with ammunition loaded with Enduron technology will be very consistent.
  • Enduron powders provide optimal load density, assisting in maintaining low standard deviations in velocity and pressure, a key feature for top accuracy.
  • Enduron technology is environmentally friendly, crafted using raw materials that are not harmful to the environment.

Hodgdon IMR Enduron 4955 temperature stable powder reduced fouling

New IMR 4955 for Larger Cartridges
For 2016, IMR has introduced IMR 4955, a new Enduron extruded powder that is a top performer with popular cartridges such as 270 Winchester, 25-06 Remington, 280 Remington, 300 Winchester Magnum and many more. This new powder falls directly between the new IMR 4451 and IMR 7977 in burn speed, providing excellent performance for most big-game cartridges. Like all Enduron Technology powders, IMR 4955 is temperature insensitive, as shown below.

Hodgdon IMR Enduron 4955 temperature stable powder reduced fouling

Adding this propellant to the Enduron line filled in an important place on reloading benches. IMR 4955, plus the original three Enduron powders, provide excellent loading solutions for cartridges from 223 Remington to the massive 500 Nitro Express Magnum. Further, in these days of powder shortages, these new Enduron powders can fill a gap by providing comparable performance to select Hodgdon® powders. Specifically, IMR 4955 is a great choice for cartridges that work well with Hodgdon H4831.

Hodgdon IMR Enduron 4955 temperature stable powder reduced fouling

IMR Enduron 4955 is available in one-pound (1 lb.) and eight-pound (8 lb.) containers from quality reloading retailers.

Permalink New Product, Reloading 4 Comments »
January 17th, 2016

New Vihtavouri Reload App for Mobile Devices

Vihtavuori RELOAD Android iOS Apple iphone smartphone App Application Play Store

Are you a 6 PPC shooter who relies on Vihtavuori N133? Or maybe you’re a .45 ACP Bullseye shooter who uses N310 or N320. Or perhaps you favor N150 in your 6mmBR or .308 Winchester. If you are a Vihtavuori powder user (or are considering trying these fine Finnish powders), then check out Vihtavuori’s new FREE mobile App.

The new Vihtavuori Reload App lets you keep track of your favorite reloading recipes, and manage load development. You can log load recipes for as many firearms and cartridge types as you want. The App holds all relevant data — cartridge class, bullet, loads specs. The Vihtavuori Reload App also provides instant access to the latest Vihtavuori Reloading Data as well as other Vihtavuori information. If you want hard copy of your load recipes, just email the recipe(s) to your personal e-mail account and then you can print out the info with a networked printer.

Download for iOS from Apple App Store | Download for Android from Google Play Store

Vihtavuori RELOAD Android iOS Apple iphone smartphone App Application Play Store

For over 90 years, Vihtavuori has been known for producing high-quality propellants with reliable ballistic performance, long shelf-Life, and a wide selection of burn rates. Vihtavuori powders are manufactured to very high standards, and many world records have been set with Vihtavuori propellants. For more information, visit www.Vihtavuori.com.

Permalink New Product, Reloading 1 Comment »