With spring soon changing to summer, we are in peak varmint season in many parts of the country. In an area with a high number of critters, a semi-auto varmint rifle is a good choice. You get quick follow-up shots, with reliable 20-rd and 30-rd magazines.
For this Saturday at the Movies Showcase we feature a variety of semi-auto, AR-platform rifles chambered for efficient, high-velocity varmint ammo. Cartridges include: .17 WSM, .17 Remington, .20 Practical, .204 Ruger, .22 Grendel, .223 Rem, and 6mm ARC. We conclude with a video that reviews a variety of lead-free .223 Rem ammo types.
Rock Chuck Hunting in Eastern Oregon
This video has some great backcountry footage. The host nails a number of rockchucks with his .223 Rem-chambered AR-15. The shooter says that the default AR-15 cartridge works great for varmints: “The .223 Remington becomes a rockchuck hunter’s friend with the right load: Nosler 40gr Ballistic Tip loaded over a stuffed case of H335 powder. This achieves 3800 FPS with excellent accuracy.”
.17 Remington AR-15 — Small Bullet, Ultra-High Velocity
The .17 Remington wildcat is based on the .223 Remington case necked down to .172″, with the shoulder moved back. High muzzle velocity (4000+ FPS), flat trajectory, and very low recoil are the .17 Remington’s primary attributes. It has a maximum effective range of about 440 yards on prairie dog-sized animals, but the low BCs of the small .17-cal bullets makes them quite susceptible to crosswinds at such distances.
This Varminter.com video was created in spring 2022, just in time for Rockchuck and Thermal Coyote hunts. The host noted: “This was my first experience with the .17 Remington, but I was not unaware of its history and steady popularity among varmint and predator hunters. Although finding an available and affordable .17 Remington bolt-action rifle is nearly impossible nowadays, building one in an AR-15 was simple and straight-forward.” The video has full description of all the components for the build. The .17 Rem is fast — the 25gr bullet runs 3777 FPS from an 18″ barrel (see 01:42 time-mark). READ Full Story.
.17 WSM Rimfire in Franklin Armory F17-L
What’s the ultimate rimfire varmint rifle? An AR chambered for the .17 WSM could be the answer. Eric Mayer of Varminter.com states: “The Franklin Armory F17-L in .17 Winchester Super Magnum (WSM) has a lot of firsts. It is the first semi-automatic rifle in .17 WSM now available to the general public. It is the first gas-piston system, AR-15 rimfire rifle built in partnership between Franklin Armory and Osprey Defense.”
Eric has used the .17 WSM AR shooting ground squirrels, rock squirrels, prairie dogs, and rabbits. Eric notes: “The report of the .17 WSM is nowhere near as loud as most of the centerfire [varmint] cartridges. I found that when I shot the FA-17, it did not cause the other ground squirrels… to run for cover. The lack of recoil … allowed me to see right where I hit [and] if I happened to miss, [low recoil] made for quick corrections for wind, or distance.” READ Full Report
The .17 WSM is a much larger, more powerful round than the .17 HMR. See the size difference above.
Eric Mayer created his own custom .17 WSM AR-15 varmint rifle, built with a Franklin Armory F17-V4 Upper, Aero Precision Lower, and Magpul stock. This was used in California and Arizona. READ Full Story.
.20 Practical — Fast, Accurate, Easy to Form
The .20 Practical cartridge is simply a .223 Rem necked down to .20 caliber. This is a great choice for prairie dogs — and probably our favorite wildcat for the AR-15. Just neck down your .223 Rem brass, fit a .20-Cal barrel and you’re good to go. Robert Whitley notes the the .20 Practical “is a perfect cartridge for varmint hunting and general shooting — very accurate and fast! It functions 100% out of an AR-15.”
The .20 Practical offers some notable advantages for high-volume varmint shooters. The .20 Practical delivers very high velocity with very low recoil while still providing outstanding accuracy. The .20 Practical is great option for folks who favor “fast and light” — smaller, lower-mass bullets traveling at very high velocities. This little cartridge can launch 40-grainers at over 3900 FPS, and 32-grainers even faster. This makes the .20 Practical a great choice for an AR-based varmint rifle.
.20 Practical Ultimate AR Varminter
A decade ago AccurateShooter.com created a .20 Practical AR15 Ultimate Varminter with a custom 20-caliber upper from Robert Whitley of AR-X Enterprises, LLC. That project rifle was ultra-accurate — every 5-shot group out of the gun was less than the size of a dime. That gun was auctioned off, but Robert Whitley continues to produce custom 20 Practical AR-15 uppers.
You make .20 Practical cases by simply necking down .223 Rem brass to .20 caliber. You can start with standard .223 Rem brass and even load with standard .223 Rem dies. Just swap in a smaller expander and use smaller neck bushings.
Prairie Dog Hunt with .204 Ruger AR — Watch The P-Dogs Fly
The video was created during a 2018 prairie dog safari. It has stunning footage of hits on P-Dogs at multiple distances. You can see over FIFTY hits with some amazing P-Dog aerials. Watch the first flyin’ dog at 00:20 time-mark and there’s a truly spectacular gut-busting hit at 3:13. That shows the potency of a high-speed .20-cal projectile. The shooter was using a custom-built AR-15 chambered in a .204 Ruger. That cartridge was driving 35gr Berger hollow point bullets at a stunning 4050 FPS! The rifle was fitted with a Dakota silencer suppressor and many other custom components. If you’ve never tried prairie dog hunting, watch this video start to finish and you may be hooked.
6mm ARC AR-15 Varmint Rig
This Varminter.com video examines the 6mm ARC cartridge from a varmint hunter’s perspective. Created by Hornady, the 6mm ARC was designed for target shooting and medium-sized game both in bolt guns and Modern Sporting Rifles. Hornady states: “The 6mm ARC … fits in an AR-15-pattern action, functions reliably out of standard-capacity 24- or 17-round magazines. It delivers substantially better ballistics than the .223 Rem[.]” This video examines how the 6mm ARC performs in an AR-15 for varmint and predator hunting. The host reviews available factory varmint loads. The video also examines reloading components for the 6mm ARC — brass and bullets. CLICK HERE for full article.
Cottontail Rabbit Hunting with Suppressed .204 Ruger AR-15
As a varmint hunting tool, the .204 Ruger in an AR-15 is a versatile, worthy cartridge/rifle combo for the job. This video covers a cottontail rabbit hunt. The host states that “We were contacted by a farmer who was being slammed with cottontail rabbits eating out huge portions of his alfalfa fields.” This suppressed .204 Ruger AR-15 proved seriously effective on the rabbits, driving high-velocity rounds with impressive accuracy. See more details on the Varminter.com website.
The .22 Grendel is an extremely accurate and efficient cartridge based on the 6.5 Grendel necked down to .22 caliber. The case can drive 55gr varmint bullets at high velocities — over 3500 FPS. With a faster-twist barrel you can load up to 90gr bullets at 2500 FPS. The tester achieved velocities close to a 22-250. The short, fat case fits in AR-15 magazines, but may not feed as reliably during rapid fire. The tester did experience one double-feed.
Lead-Free Ammo Offerings Tested in .223 Rem AR-15
Some states — such as California — prohibit hunting with bullets that contain lead. If you plan to hunt in an area with such restrictions, you’ll need to find a lead-free substitute. Thankfully a number of manufacturers produce ammo with solid brass projectiles or other lead-free bullet designs. This Varminter.com video reviews .223 Remington no-lead ammunition from Cor-Bon, Hornady, Nosler and Winchester. These ammo types were tested in a AR-15 varmint rifle, used in a coyote hunt featured at the end of the video. SEE Full Story on Varminter.com.
AR owners know that their black rifles require regular cleaning and maintenance. And this modular platform allows many options for stocks, fore-arms, and optics mounting. That ability to customize is one of the AR’s major attractions, but customization requires solid understanding of the AR’s design and components.
GET FREE 40-Page AR-15 Book Sample
Note, if you are interested in the book, there is a substantial 40+ page FREE sample available on the Amazon site. You can see the entirety of the first two chapters from the Kindle digital version. CLICK HERE to visit Amazon.com and then click on the button labeled “Read Sample” below the cover image.
AR Set-Up and Maintenance
If you need to disassemble and maintain your AR rifle, swap barrels or handguards, add optics, or customize the stock, Gun Digest’s AR-15 Setup, Maintenance and Repair book tells you what you need to know. From field-stripping to barrel mounting and trigger installations, the book covers a wide range of topics. The book provides step-by-step instructions for set-up and maintenance, with hundreds of detailed photos. The book also includes AR gunsmithing chapters with reviews of recommended tools.
Author Patrick Sweeney is a certified master gunsmith and armorer instructor for police departments. Sweeney has also authored the notable 4-volume Gunsmithing the AR-15 series (Vol. 1, Vol. 2, Vol. 3, and Vol. 4) and 20+ other titles for Gun Digest Books.
Whether you want to learn about disassembling your AR for regular maintenance, field-stripping, swapping out parts, adding optics or customizing a stock, AR-15 Setup, Maintenance and Repair guides you through everything you need to know to keep your AR-platform rifle running well. There are also tips on how to improve accuracy, and maintain your bolt carrier group properly.
Authored by Patrick Sweeney
Published by Gun Digest Books
ISBN-13: 978-1951115470
320 pages, softcover, 8 ¼ x 10 7/8 inches
Editor’s NOTE: The key to keeping an AR running reliably is proper lubrication (in the RIGHT places), and regular cleaning of the bolt carrier and bolt, including ejector recess and extractor recess. The majority of non-functioning ARs we’ve seen had gunk, lube, carbon, and brass shavings in those recesses.
Other AR Books by Patrick Sweeney
Bonus Video — AR15 Maintenance with Jerry Miculek
In this helpful video, legendary shooting Jerry Miculek explains how he cleans and maintains his AR-platform rifles. Miculek shoots ARs in three-gun competitions.
It’s now the month of May, so summer shooting season is right around the corner for the whole nation. Before you head to the range for the first time, we recommend you do some basic tasks with your firearms. Here’s some good advice on readying your rifles for the 2026 shooting season.
by Ron Dague, Sinclair International I give my rifles a pre-season check before the shooting season starts. This starts with a general inspection starting with the butt-plate or recoil pad and making sure that all the screws and adjustable parts (on an adjustable butt-plate) move freely up or down and side to side. If you got caught in rain some of these screws and adjustable parts may not move when needed. I disassemble parts as needed and put rust preventative or a light oil and/or grease on threads and sliding parts. On rifles with recoil pads and fixed butt-plates, make sure the screws are tight and that holes in the stock aren’t stripped out. Also make sure there are no cracks in the stock and around the butt-plate. And if the recoil pad is glued-on, just make sure it hasn’t come loose.
Next I take the action out of the stock and check for cracks and wear marks. I look at the bedding to make sure that oils and cleaning solvents have not damaged the bedding. While the action is out of the stock, I look for any surface rust or dirt/dust in the recoil lug area and magazine well. Clean as needed and repair or re-bed if needed.
Trigger Assembly and Action With the barreled action out of the stock, it is a good time to spray out the trigger with cleaner. I use Ronson oil or lighter fluid. [Editor’s Note: Some trigger-makers advise against using any kind of lubricant, grease or oil — so plain lighter fluid is preferred.] After the trigger is cleaned you may want to check the trigger pull weight. If you don’t feel comfortable doing this, take it to a gun smith and have it checked. It is worth every penny to not have a trigger issue and/or a safety malfunction. I also take the bolt apart and clean the firing pin spring and bolt housing with Gun Scrubber or automotive brake cleaner. Then lube the firing pin-spring and firing pin with light oil. I use Kel Lube and/or Butch’s gun oil. Put a small dab of gun grease on the [bolt locking lugs] and cocking ramp.
I will also spray the outside of the action and barrel and give that a light coating of oil for rust prevention. I clean the action with Sinclair’s action cleaning tool. Don’t forget to clean the bore. Even though you didn’t fire the rifle, this makes sure nothing obstructs your barrel.
Checking Metal Fixtures and Fasteners Next I look at the trigger guard and hinged floor plate and make sure it works as designed. Make sure there are no cracks in the trigger guard from an accidental drop. Check guard screws and /or action screws for tightness and tighten to proper spec. There are torque specs for this, but on wood stocks the wood can crush and this should be checked throughout the year as weather change can affect this. My entire collection of rifles are bedded and I just tighten them just snug with screw driver or Allen wrench. The rimfire rifles have a spec of 55 to 74 inch/lbs and I think would carry over to center fire as well. I would caution you about torque wrenches as you need a good quality wrench, and read the directions on how to use it. You can over torque if not careful. Check the swivel studs and bipod to make sure there tight as well. You may want to take scope off and check the base screws and check the rings.
Test Fire the Rifle After Maintenance
After all cleaning and is done and everything is reassembled, take a few rounds out to the range and test fire to make sure everything works as it should. Don’t forget to run 3-5 rounds through the magazine at least two times for function. I look at this as preventive maintenance on the rifle. If you give it a look over you shouldn’t have any trouble during the rifle matches or hunting trip.
Ron Dague
Certified Reloading Instructor
Certified Range Safety Officer
Email: rond [at] sinclairintl.com
Phone: 800-717-8211
This Article Originally Appeared in Sinclair International’s The Reloading Press.
Civilian Marksmanship Program (CMP) Provides $10 Million Challenge Grant for WSSC
The Board of Directors of the Civilian Marksmanship Program (CMP) has approved a $10 million challenge grant for development of the new Wyoming State Shooting Complex (WSSC) in Cody, Wyoming. This marks a major milestone in the CMP’s strategic “Western Expansion”, establishing a permanent footprint to serve marksmanship enthusiasts west of the Mississippi River.
The new WSSC is now under development on 2,000 acres of state-contributed land located just seven miles south of downtown Cody. Positioned near Yellowstone National Park, the complex will become a premiere shooting sports destination, with purpose-built venues for elite competitors, recreational shooters, and youth programs.
The $10 million grant is structured as a matching initiative for three years. Under the agreement, the CMP will match new private and industry WSSC donations dollar-for-dollar, up to $10 million total.
Construction Is Underway with State Governmental Approval
The WSSC project has earned full support from the Wyoming Legislature and Governor, and it is governed by a Joint Powers Board representing city and county leadership. Construction is already underway, with core infrastructure and internal roads currently being established.
“Cody, Wyoming, is a great choice for Western expansion,” CMP Board Member and Wyoming resident Ed Newell noted following a site visit. The [WSSC] offers a unique opportunity for a high-impact partnership consistent with CMP’s mission to promote youth programs, marksmanship and firearms safety.
Above, U.S. Senator Barrasso shows the WSSC event center, which will include a retail area, classroom, kitchen, and a multi-purpose conference hall that can also be used for indoor archery and air gun.
The WSSC is designed to be a world-class destination for shooting sports. Its mission is to inspire youth participation, promote responsible firearm use, and serve as a catalyst for economic growth and outdoor recreation in the State of Wyoming and our nation.
Beyond the financial contribution, the CMP partnership includes key collaborative elements:
Expert Range Design: The CMP will provide technical input on range design to ensure the facility can host the organization’s signature matches and national-level competitions.
On-Site CMP Store: There’s a plan for the WSSC clubhouse to feature a CMP Store which would provide visitors with access to historic American firearms.
Nearby Buffalo Bill Museum: The WSSC’s proximity to the Buffalo Bill Center of the West, which houses over 7,000 firearms, will create a unique “view it, learn it, then buy it” experience for the more than one million tourists who visit the area annually.
Photo courtesy NRA MuseumClick Photo to View Larger Image
With today’s polymer-framed Glocks and Kel-Tecs, aesthetics have been sacrificed on the altar of functionality. Not so in the early 20th century — in that period, the best firearm designers created guns that looked as good as they worked. One example is the classic Colt Woodsman. This design came from the legendary John Moses Browning and was later refined by Colt before the pistol’s introduction in 1915. The Colt Woodsman’s frame design evolved over time in three distinct series: Series One 1915–1947, Series Two 1947–1955, and Series Three 1955–1977. Shown above is a stunning Carbonia-blued and engraved Third Series model with ivory grips.
Engraved Colt Woodsman from NRA Museum
In the NRA Museum’s Robert E. Petersen Gallery are many fine engraved arms. This Colt Woodsman .22 pistol is one of the Third Series guns that were made until 1977. Heavy barrels in either 4.5 or 6 inch lengths were offered in this variation. The Museum’s staff says: “We think the poised golden rattlesnake near the serial number is the [best] embellishment without putting down in any way the ivory grip panels or gold outline inlays.”
You can see this lovely Colt and countless other fine firearms at the NRA Museum in Fairfax, Virginia. The Museum is open every day from 9:30 am to 5:00 pm, and admission is free.
The Colt Woodsman was made in many variations, with different barrel lengths and contours and finishes. Here is a Colt Woodsman Third Series Match Target with 6″ Blued frame and slab barrel. Photo from Sam Lisker’s ColtAutos.com.
Here is a Colt Woodsman First Series Match Target with 6.5″ undercut slab match barrel and basic blued finish. Photo from Heritage Auctions.
Here is a Colt Woodsman Bullseye Match Target Pistol (6.5″ barrel) with blued finish and early factory “elephant ear” stocks with Colt medallions. This was owned by Philip Judd, an avid marksman who was 1952 Camp Perry Champion in the 500-yard .30-06 rifle competition. Photo from Sam Lisker’s ColtAutos.com.
With rising crime rates in the USA, many Americans are taking a much more serious look at armed self-defense. We understand why citizens in large cities are more concerned than ever with the need to protect themselves, their families, and their homes and businesses.
Shotgun vs. Handgun — which is better for home defense? That question inspires strong opinions on both sides. We think the best answer may be “both”. There are some situations where a pistol is most handy, while there are other situations where the power (and lethality) of the shotgun clearly wins out. Some would argue that the shotgun offers an “intimidation” factor that may better resolve a threat without a shot being fired.
The NSSF, in cooperation with Thunder Ranch Training Center, has created an interesting video that examines the Shotgun vs. Handgun debate. As the Cheaper Than Dirt Blog notes: “The primary argument against the shotgun is a longer length leading to less maneuverability. On the other hand, the pistol offers better maneuverability, but lacks the stopping power of a shotgun”. Moreover, the pistol may be less accurate, according to some critics. This NSSF video looks at the question from a logical standpoint — making some surprising points.
As you can see in this still frame (above) from the video, the shooting stance of the pistol shooter (Clint) is NOT much more compact than that of the two shotgunners (compare actual muzzle positions). So a shotgun may actually be more handy inside a home than some people realize. Clint concludes that the gun selection debate “is all very easily solved by only one question: ‘If someone was going to run across a bedroom at you and they had a big knife, would you rather shoot him one time with a pistol or one time with a shotgun?’ When you answer the question you figure out why this [shotgun length] doesn’t really bother us. We simply take these [shotguns] and use them in a slightly different manner…”
In this video, Thunder Ranch Director Clint Smith explains why the overall length of a shotgun, as held in firing position against the shoulder, is not really that much greater than the “shooting stance length” of a handgun held in a proper firing position (with arms extended). Accordingly gun length/size should not be the deciding factor when choosing a firearm for home defense.
Whatever Weapon You Choose — Train with It
Fundamentally, you should use the firearm that is 100% reliable, and with which you have trained regularly. Mastery of a defensive firearm — whether shotgun or handgun — needs to be second-nature. You should be able to operate all the controls (safety, pump, decocker, slide, bolt handle etc.) by “instinct” based on hours of training. Likewise you should know how to operate the light/laser if your defensive firearm is so equipped. Importantly, you should be able to reload in darkness, and clear malfunctions without panicking.
The RCBS Lock-Out Die can also be used with some Dillon and Hornady progressive presses.
If you load pistol or rifle ammo with a progressive press, we strongly recommend you get a Lock-Out Die from RCBS. This unique reloading die will prevent your progressive press from advancing if the dispensed powder charge is more or less than about 0.3 grains too high or too low. The Lock-Out Die really works. Your Editor uses it on his RCBS 2000 progressive press. I can affirm that a Lock-Out Die has “saved my bacon” a half-dozen times over the years when there was an over-charge (which could cause a Kaboom) or a low charge (which could cause a squib load).
The Lock-Out Die works by using a central die detection rod that sets its vertical position based on the height of the powder column in the case. Through an ingenious design, if the powder column height is too low or too high, the rod locks in place as you start to pull the press handle. This halts the press before the ram can lift and the cartridge plate can advance. Unlike a beeping alarm system (which can be ignored or defeated), the Lock-Out Die physically stops the movement of the press ram and prevents a bullet being seated in the “problem” case.
It takes a bit of tweaking to get the Lock-Out Die detection rod setting just right, but once it is correctly positioned, the Lock-Out Die works smoothly in the background. The Lock-Out Die won’t interfere with the loading process unless it detects a high or low charge — and then it positively stops the progressive loading cycle.
While crafted for use in RCBS progressive presses, the RCBS Lock-Out Die can also be used on a Dillon XL Progressive (see video below) or Hornady Lock-N-Load progressive — though it does take up one station which could otherwise be used for a final crimp die (after the seating die). The RCBS 2000 has one more station than a Dillon 550/650, so it’s an ideal platform for using the Lock-Out Die.
Learn More at UltimateReloader.com
On the UltimateReloader.com website, run by our friend Gavin Gear, you’ll find an excellent two-part series on the function and set-up of the RCBS Lock-Out Die. Part One explains how the Lock-Out Die functions, using cut-away illustrations. Part Two shows how to install and adjust the Lock-Out Die on various progressive presses. The Ultimate Reloader video at the top of this article shows setup of the RCBS Lock-Out Die on the Dillon XL-650 progressive press, while the Reloading Bench video below shows the Lock-Out Die on a Hornady LnL progressive.
Close-up view of a sectioned case. This one here was “fixin’ to pop”, observed Glen Zediker.
Here are highlights from an article Glen Zediker wrote for the Midsouth Blog. In that article Glen, who sadly passed away in 2020, focused on cartridge brass. Glen identified the most common failures that appear with brass that has been shot multiple times, or which has been fired at excessive pressures. Glen explained some simple ways to check your cartridge brass to detect “early warning signs” of case failure, particularly case head separation, which can be very dangerous.
How Cases Degrade with Multiple Firings By Glen Zediker
This article explains when, and then how, to check after the progress of changes commencing with the firing on a new case. It’s the “progress of degeneration,” in a way of looking at it because the concern is getting a handle on when enough change in the brass has come about to require attention. Or abandonment. As said then, for me that’s 4 firings. That, as said last time, is when I might see changes that need attention. Also as said, that figure didn’t come out of a hat, but from my own notes in running my competition NRA High Power Rifle loads. [Editor’s Note: With Lapua brass, using moderate loads, in bolt-action rifles, we typically get about 10 good (match-worthy) firings. But if you anneal your Lapua brass, and run modest pressures, Lapua brass can perform well for 20 or more load cycles.]
The areas most affected are the case neck and case head area. Case neck walls get thicker [but] the case head area body walls get thinner. Primer pockets get shallower and larger diameter.
This case shows a cracked neck AND a crack (separation) above the case head. Zediker says it is “rare to see one case with both of the most common failures. [This case] was attacked by an M14.”
Case Head — Causes of Separation and Cracking
When a case is under pressure during firing, the brass, like water, flows where it can, where it’s more free to move. Of course, the chamber steel limits the amount it can expand. The case shoulder blows fully forward and the case base is slammed back against the bolt face. There is, therefore and in effect, a tug on both ends — it gets stretched. The shoulder area is relatively free to expand to conform to the chamber, but the other end, the case head area, is not. Since that’s the area of the case with the thickest walls, it doesn’t expand “out” much at all. What it does is stretch. The “case head area,” as I refer to it here, is the portion of the case above the web, which is just above the taper that leads in to the extractor groove. The “area” extends approximately an eighth-inch up the case body.
Here’s a “pressure ring.” You’ll see this after firing, if you see it. And, if you see it, that case is done. The bright ring indicates excessive stretching, which indicates excessive thinning. If you see a ring circling the case, noticeable because it’s lighter color than the case body, and it’s in this area, I’d say that case is done. And that’s right where a “head separation” occurs. It can crack and also blow slap in two, and that’s the “separation” part of case head separation.
Photo courtesy GS Arizona.
This is a spot to keep close watch on as cases age. It is also the area that is more “protected” by sizing with less case shoulder set-back. That is, pretty much, where the freedom for the stretching movement in this area comes from (the case shoulder creates a gap). If you’re seeing a sign that a head separation [might happen with relatively few firings], chances are the shoulder set-back is excessive, and also… the load pressure level.
Bent Paper Clip Case-Wall Gauge
Editor: You can use a bent paper clip to detect potential case wall problems. Slide the paper clip inside your case to check for thin spots. GS Arizona explains: “This simple little tool (bent paper clip) will let you check the inside of cases before you reload them. The thin spot will be immediately apparent as you run the clip up the inside of the case. If you’re seeing a shiny line on the outside and the clip is really hitting a thin spot inside, it’s time to retire the case.” Photo by GS Arizona.
Monitor Primer Pocket Dimensional Changes
Another case-head-area and pressure-related check is the primer pocket. As said, the primer pocket will get larger in diameter and shallower in depth each firing. As with many such things, the questions are “when” and “how much,” and the main thing, “how much?”
If the pocket gets excessively shallow, and that’s judged by a primer that seats fully but isn’t at least a tick below flush with the case base, there could be function issues. There’s a risk of a “slam-fire” with a semi-auto that uses a floating firing pin, and, if there is actual protrusion, that has the same effect as insufficient headspace. A primer pocket uniformer can reset the depth of a shallowed primer pocket to what it should be, but the real test for me is how easily the next primer seats into it. If it’s significantly less resistance, I’ll say that case is done. Shallower can be refurbished. That’s a primary function of a primer pocket uniformer. Larger diameter, though, can’t be fixed. I’ve mentioned in another article or two that, any more at least, my main gauge of load pressure has become how much primer pocket expansion there’s been.
“A bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.”
A few seasons back a good friend ventured to the high country of Colorado to pursue elk. He recently zeroed his rifle in California, at a range just a few hundred feet Above Mean Sea Level (AMSL). He wondered if the higher altitude in Colorado could alter his ballistics. The answer is a definite yes. However the good news is that free ballistics calculators can help you plot reliable drop charts for various shooting locations, high or low.
The question has been posed: “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, at higher altitudes, the bullet behaves as if it has a higher ballistic coefficient.
Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:
“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ AMSL (Above Mean Sea Level) or less. I’ll need about 29-30 MOA to get from 100 yards to 1000 yards with a Berger 155gr VLD at 2960 fps. By contrast, in Raton, NM, located at 6600′ AMSL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.
Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”
As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect. It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet AMSL), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestrel, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.
Trajectory of Bullet fired at Sea Level
Trajectory of Bullet fired at 20,000 feet
You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.
To learn more about all aspects of Exterior Ballistics, Hornady has a useful discussion of External Ballistics including the effects of altitude and temperature. To dig deeper, Sierra Bullets has a comprehensive Exterior Ballistics Resource Page with multiple sections from the Sierra Manual (4th and 5th Editions), including:
Section 3.0: Exterior Ballistic Effects on Bullet Flight
Section 3.1: Effects of Altitude and Atmospheric Conditions
Section 3.2: Effects of Wind
Section 3.3: Effects of Shooting Uphill or Downhill
Example from Section 3.0: “When a bullet flies through the air, two types of forces act on the bullet to determine its path (trajectory) through the air. The first is gravitational force; the other is aerodynamics. Several kinds of aerodynamic forces act on a bullet: drag, lift, side forces, Magnus force, spin damping force, pitch damping force, and Magnus cross force. The most important of these aerodynamic forces is drag. All the others are very small in comparison when the bullet is spin-stabilized.”
Larry Medler has come up with a smart little invention — a simple, inexpensive Empty Chamber Indicator for rimfire rifles. It is made from a section of plastic “weed-wacker” line and a wooden ball from a hobby shop. Larry says he was inspired by Juniors who used something similar for their 17-Caliber Air Rifles.
How to Make the Empty Chamber Indicator
Construction Method: First, drill a 7/64″ diameter hole all the way through the 1″-diameter wooden ball. Then enlarge half of that 1″-long hole using a 13/64” diameter drill. Next insert an 8″ piece of heavy duty (0.095″ diameter) weed wacker line through the ball, leaving about 2″ on the side with the bigger-diameter hole. Then, with the short end of the line, fold over the last half-inch so the line is doubled-over on itself. Then slide the line into the ball, stuffing the doubled-over section through the 13/64″ (large) hole. Finally, pull the longer end of the line until the doubled-over section is flush with the outside of the ball. This gives you a sturdy line attachment without messy adhesives. When the assembly’s complete, hold the ECI by the tail and dip the ball in yellow paint. If you’re making more than one ECI, you can drill horizontal holes in a spare block of wood and use that as a drying rack.
At a Rimfire Sporter match like this, all shooters must have an Empty Chamber Indicator.
The Empty Chamber Indicator for Smallbore Rifles
Larry explains: “At all Highpower rifle matches, silhouette matches, and other shooting events I have attended, Open Bore Indicators (OBI), or what are now called Empty Chamber Indicators (ECI) have been mandatory. The NRA’s yellow ECI for Highpower rifles is easy to use and has been well-received by the shooters. However, I had not seen a truly workable ECI for 22 rimfire rifles — until I visited Michigan’s Washtenaw Sportsman’s Club where I saw juniors using ECIs for their 17 Caliber Air Rifles. Someone at the club made the empty chamber indicators by attaching an 8″ piece of weed wacker line to a 1″-diameter wooden ball, painted bright yellow. I now make similar ECIs for the 22 rimfire silhouette matches I run.”
.20 Practical Ultimate AR Varminter
I give my rifles a pre-season check before the shooting season starts. This starts with a general inspection starting with the butt-plate or recoil pad and making sure that all the screws and adjustable parts (on an adjustable butt-plate) move freely up or down and side to side. If you got caught in rain some of these screws and adjustable parts may not move when needed. I disassemble parts as needed and put rust preventative or a light oil and/or grease on threads and sliding parts. On rifles with recoil pads and fixed butt-plates, make sure the screws are tight and that holes in the stock aren’t stripped out. Also make sure there are no cracks in the stock and around the butt-plate. And if the recoil pad is glued-on, just make sure it hasn’t come loose.
With the barreled action out of the stock, it is a good time to spray out the trigger with cleaner. I use Ronson oil or lighter fluid. [Editor’s Note: Some trigger-makers advise against using any kind of lubricant, grease or oil — so plain lighter fluid is preferred.] After the trigger is cleaned you may want to check the trigger pull weight. If you don’t feel comfortable doing this, take it to a gun smith and have it checked. It is worth every penny to not have a trigger issue and/or a safety malfunction. I also take the bolt apart and clean the firing pin spring and bolt housing with Gun Scrubber or automotive brake cleaner. Then lube the firing pin-spring and firing pin with light oil. I use Kel Lube and/or Butch’s gun oil. Put a small dab of gun grease on the [bolt locking lugs] and cocking ramp.
Next I look at the trigger guard and hinged floor plate and make sure it works as designed. Make sure there are no cracks in the trigger guard from an accidental drop. Check guard screws and /or action screws for tightness and tighten to proper spec. There are torque specs for this, but on wood stocks the wood can crush and this should be checked throughout the year as weather change can affect this. My entire collection of rifles are bedded and I just tighten them just snug with screw driver or Allen wrench. The rimfire rifles have a spec of 55 to 74 inch/lbs and I think would carry over to center fire as well. I would caution you about torque wrenches as you need a good quality wrench, and read the directions on how to use it. You can over torque if not careful. Check the swivel studs and bipod to make sure there tight as well. You may want to take scope off and check the base screws and check the rings.
Engraved Colt Woodsman from NRA Museum
If you load pistol or rifle ammo with a progressive press, we strongly recommend you get a Lock-Out Die from RCBS. This unique reloading die will prevent your progressive press from advancing if the dispensed powder charge is more or less than about 0.3 grains too high or too low. The Lock-Out Die really works. Your Editor uses it on his RCBS 2000 progressive press. I can affirm that a Lock-Out Die has “saved my bacon” a half-dozen times over the years when there was an over-charge (which could cause a Kaboom) or a low charge (which could cause a squib load).
The question has been posed: “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, at higher altitudes, the bullet behaves as if it has a higher ballistic coefficient.
