In the past the U.S. Army Marksmanship Unit published a series of reloading “how-to” articles on its USAMU Facebook page. One “Handloading Hump Day” article covered two basic case prep chores — uniforming primer pockets and deburring flash-holes. Visit the USAMU Facebook page for other tips.
Primer Pocket & Flash-Hole Conditioning
This week, we’ll address a question that frequently arises: “Do you uniform primer pockets and deburr flash-holes?” As we tailor our handloading methods to the specific needs of each instance, the answer, not surprisingly, is “Sometimes!” However, don’t flip that dial just yet, as what determines our approach may be helpful in deciding how to address one’s own techniques. Moreover, we have a buried “Easter Egg” morsel that may bring a chuckle, as well as useful safety information!
Generally, the USAMU Handloading Shop does not uniform primer pockets (PP) or deburr flash holes (FH) of our rifle brass. We’re certainly not against it… Rather, this reflects the very high volume of ammunition we load, the fact that very few cases are ever re-loaded for a second firing, and the types of brass we use. However, as a need is perceived, we DO deburr flash holes. Of interest, we have fired many very small, 1000-yard test groups and aggregates using weight-selected, domestic brass that had not had PPs uniformed or FHs deburred.
Before and After — On the left is a fired, deprimed 7.62×51 case with primer residue intact. On the right the primer pocket has been uniformed to SAAMI specs. Note the shiny finish at the bottom of the pocket — evidence of the the removal of metal when uniforming the primer pocket.
As to the type cases we use, many thousands of our long-range 5.56mm cases come to us from the arsenal with the primer of our choice pre-installed and staked-in, per usual practice. Obviously, we cannot uniform either FHs or PPs on this live, primed brass. However, after careful sorting, inspection and preparation, we do obtain match-winning results with it.
Shooters who reload their brass several times may decide to uniform PPs and deburr FHs, especially on their “300-yard and beyond” brass. Here, they will use the cases many times, while the uniforming is performed only once. Also, most handloaders only process moderate amounts of brass, compared to our multi-thousand round lots.
Having high quality Long Range (LR) brass helps. Many of the better brass manufacturers [make] their flash holes so that no burrs are created. Still, it does pay to inspect even THESE manufacturer’s products, as occasional slips are inevitable. Very rarely, some of the best makers will have a significant burr in, say, 1 per 1000 or 2000 cases, and it’s worth catching those.
Exceptions can always be found. Recently, we began processing a large lot of match brass from a premier manufacturer. We were startled to find that every case had a significant burr in the FH — something we’d never before seen from this maker. We then broke out the FH deburring tools and went to work.
Some observers have noted that it can be difficult to truly verify the contribution to accuracy of these procedures — particularly when firing from the shoulder, in conditions. Members of this staff, as individual rifle competitors, do often perform these operations on their privately-owned LR rifle brass. One could ascribe this to the old High Power Rifle maxim that “if you think it helps, then it helps.”
However, a World Champion and Olympic Gold/Silver medalist here commented on his own handloading (for International competition, which demands VERY fine accuracy). He noted that he did seem to see a decline in accuracy whenever he did not uniform FHs, deburr FHs and clean primer pockets before each reloading. (One might be tempted to counter that only a truly World Class shooter could reliably detect the difference.) However, with the wisdom of decades experience, our Champion also remarked that “It could have been that I just wasn’t shooting as well that day.”
For those who do opt for these procedures, note that various tool models may have adjustable depth-stops; pay attention to the instructions. Some FH-deburring tools (which enter the case mouth, not the primer pocket) are dependent upon uniform case length for best results.
Above is a flash-hole deburring tool on an RCBS powered case-prep unit. These case prep machines can save a lot of pain and misery, helping one perform various functions quickly and efficiently.
At the request of our readers, we provide select “Deals of the Week”. Every Sunday afternoon or Monday morning we offer our Best Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, optics, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
NOTE: All listed products are for sale to persons 18 years of age or older. No products are intended for use by minors.
1. Bruno’s — Large Selection of McMillan Stocks 10% OFF
⏺ Great savings on quality McMillan fiberglass stocks
McMillan stocks are world-renowned for competition, tactical/precision, benchrest, and hunting applications. We found a rare deal on McMillan stocks at Bruno Shooters Supply. Find one for your next rifle project and save 10% instantly during checkout. Bruno’s has 60+ McMillan stocks available now for 10% OFF. There are many stock varieties — benchrest, hunting, tactical, F-Class. Some of these stocks may also qualify for FREE Shipping.
2. Midsouth — Berger Bullets In Stock!
⏺ Grab these great Berger Bullets before they sell out
Berger makes top-tier competition bullets but the most popular calibers have been in short supply lately. The good news is that Midsouth Shooters Supply just got a huge shipment of Berger bullets in many calibers and grain weights. This is one of the biggest Berger bullet drops we’ve seen in the past year, so don’t hesitate if you need good match bullets.
3. Graf & Sons — Ammo Sale with FREE TRI-Can Carrier
⏺ Good prices with excellent three-compartment ammo carrier
Here’s a great chance to stock up on quality .223 Rem ammunition. Right now Grafs.com is running a big sale on .223 Remington Ammo from leading makers such as Federal, Norma, Nosler, Barnes, and Winchester. As an additional incentive, if you spend $150 or more on in-stock ammo, you get the excellent Berry Tri-Can ammo carrier for free.
4. Amazon — Teslong Rigid Borescope with Monitor, $135.99
⏺ Excellent borescope complete with monitor — everything you need
Teslong borescopes let you evaluate barrel fouling and gauge the effectiveness of your cleaning regimen. We recommend the $135.99 Teslong Borescope with rigid shaft and Teslong monitor. This can use either the included monitor or your mobile device. There are other good Teslong models. We also like the rigid shaft no monitor version for $99.99 which plugs into your smartphone or tablet. There is also a less expensive flexible unit with monitor for $76.28. This uses a flexible cord rather than a metal shaft.
5. Natchez — Major Rifle and Pistol Ammunition Sale
⏺ Excellent prices, large selection of pistol and rifle ammunition
If you’re in the market for ammunition, check out the giant Natchez Ammo Mix Sale. You’ll find an great assortment of brands and calibers all at prices up to 35% off. This is a great time to stock up with quality ammo for pistols and rifles.
6. Midway — Magpul Bipod Sale
⏺ Strong high-quality bipods at significant savings, good for PRS
Whether you’re a hunter, plinker, or target shooter, a sturdy bipod is a must. And, right now, the excellent Magpul Bipods are available at significant discounts — up to 20% off normal retail prices. NOTE: You must add the bipod to your MidwayUSA shopping cart to see the near 20% Off prices: $89.99 for Magpul 933 M-Lok, $89.99 for 933 Picatinny Rail, and $104.99 for Magpul Sling Stud QD.
7. Midsouth — Lyman Tac-Mat Shooting Mat, $56.31
⏺ Thick padded mat offers more comfort with good length and carry handle
Comfort counts when you’re on the ground for hours. We like this Lyman Tac-Mat 71″ x 36″ shooting mat. It has more padding than most mats, providing significantly better comfort. Midsouth is currently offering these excellent Lyman mats for $56.31 in tan or $56.31 in black. That’s a great deal. This same Lyman shooting mat currently costs $75.19 on Amazon.
8. Amazon — OTIS Elite Cleaning Kit, $99.99
⏺ Very complete universal kit for all firearms
All firearms owners need quality tools for cleaning their pistols, rifles, and shotguns. A good choice is the Otis Elite Cleaning Kit. This universal gun cleaning kit comes complete with over 60 components for all rifles, pistols, shotguns and inline muzzleloaders, including a full tactical cleaning kit all contained in a lightweight, portable case and the best part is that it’s made in the USA.
9. Amazon — Crosman Legacy Air Rifle, $47.25
Here’s a great bargain in a basic airgun. This works for short-range plinking and can be a good training rig for someone new to shooting. The .177 Caliber Crosman Legacy air rifle which weighs just under five pounds boasts an all-weather synthetic stock and forearm. This Crosman Legacy can shoot .177 pellets or BBs with a built-in 850 BB reservoir. This inexpensive, little air rifle comes complete with 4x15mm scope and fiber optic front/rear blade sights.
10. Amazon — Tactical Pistol Light, $30.99
⏺ Good price on rugged lamp that fits pistol front rails
Do you own a Glock, Sig, HK, CZ, or Walther pistol with a standard under-barrel frame rail? A useful accessory is the 600 Lumen AUCLAYTEC Tactical Pistol Light. Get the unit with one battery for $30.99, or (as shown) with two batteries for $32.99. Crafted from aircraft aluminum, this pistol light comes with rechargeable battery and charger.
We are finally seeing prices drop a bit on loaded ammo, and there are some notable ammunition sales right now at Natchez and Palmetto State Armory. However, certain types of ammunition are in short supply — particularly 12ga shotshells and large-caliber hunting rifle ammunition.
Thankfully, if you shop around aggressively, you can still find most types of ammunition at reasonable prices. Everything from .22 Shorts to big hunting cartridges. For example, there’s a great deal right now on Norma Tac-22 .22 LR rimfire ammo at Palmetto State Armory. A good option for NRL22 training, this Norma ammo has shot very well in tests and is a steal at $3.99/per box ($0.08 per round).
If you haven’t sourced ammo online before, note that, for nearly all jurisdictions, it legal to order ammunition online and have it delivered to you at home in most states. But check your state and local laws! California, for example, has prohibited direct ammo shipments to ordinary customers.
AmmoSeek.com monitors more than a dozen online vendors — checking current pricing and available inventory, for pistol, rifle, and shotgun ammunition. Looking for .22 LR ammo for your rimfire trainer or .45 acp ammo for your 1911? Just select the cartridge type from the “Quick Seek” list on the right. Likewise you can find .223 Rem and .308 Win Rifle ammo with one click.
Got Ammo? Here’s just part of the vast inventory at Skagit Arms in Washington State.
Use Ammoseek.com to Find Reloading Components Too
Ammoseek.com also lets you search for reloading components, including powder, primers, brass, and bullets. This is a huge time-saver. You can instantly check a dozen or more vendors to see if a particular type of powder is in stock. Likewise, you can quickly check for primer availability. If you have a big match coming up and are short on primers — this could solve the problem. To search for components, from the AmmoSeek home page, click the gray “Reloading” Tab (see below), then select Bullets, Brass, Primers, or Powder from the pull-down menu.
The Modern Advancements series is an ongoing journal of the R&D activities at Applied Ballistics. Theories of ballistics are explored “myth-buster” style with extensive live fire testing. Employing state-of-the-art ballistic instrumentation including Doppler Radar and high-speed (Phantom) video, the Applied Ballistics team has made key insights about ballistics which are then shared through books and the Science of Accuracy Academy.
This 3rd Volume of the series has 13 Chapters. The book features four main parts: Part 1: Precision Testing, Part 2: Advanced Handloading, Part 3: Doppler Radar Testing, and Part 4: Miscellaneous.
Pre-orders for individuals and dealers opened July 26, 2022, and end when the books ship in late August or early September. During the pre-order phase, subscribers of The Science of Accuracy Academy will get a $20 off coupon for the new book. Other ballistics books by Bryan Litz are available through the Science of Accuracy Academy STORE.
About Applied Ballistics
Applied Ballistics’ mission is to be a complete, unbiased source of external ballistics information for long-range shooters. We’re highly active in R&D, constantly testing new claims, products, and ideas for potential merit and dispensing with the marketing hype which can make it so difficult for shooters to master the challenging discipline of long-range shooting.
We believe in the scientific method and promote mastery through an understanding of the fundamentals. Our work serves the shooting community via instructional materials which are easy to understand, and products such as ballistic software which runs on many platforms. If you’re a long-range shooter who’s eager to learn about the science of your craft, we’re here for you.
Do you plan to use factory ammo in your hunting rifles? Perhaps you buy bulk centerfire ammo for your AR15s or varmint rifles. And you’ll certainly consider using factory ammo in all your rimfire guns. Then this book can definitely benefit you.
If you ever shoot factory ammo, you should consider getting Ammo & Ballistics 6. This resource lists over 2,600 different loads for 200+ cartridge types from .17 Mach 2 up to .700 Nitro Express, including the most popular centerfire and rimfire cartridges (both rifle and handgun). In this updated-for-2020 Sixth Edition, there are over 3,000 tables covering virtually every caliber and every load for all commercially-loaded hunting ammunition sold in the USA. Tables include velocity, energy, wind drift, bullet drop, and ballistic coefficients up to 1,000 yards.
Ammo & Ballistics 6 helps you select ammo for a hunt — quickly compare the velocity and knock-down power of various commercial ammo. This book can also help you choose a caliber/chambering for your next hunting rig.
Verified Book Purchaser Reviews
“Outstanding reference guide for shooters and ballistic enthusiasts alike. Has data on velocity, energy delivered, Taylor KO index, windage and elevation on numerous loadings for hundreds of [cartridge types]. Each cartridge has all dimensions labeled (i.e rim, case length, neck, etc.), and has an informative description of the cartridges history/relevance.” — S. Step, 2017
“Great heaps of data! This volume has pages and pages of new data for .22 LR like the hot Velocitor, and also on the .22 WMR from 30 grains up into the 50s. Most importantly there is lots of range data, drop, windage, kinetic energy, etc. — Terrific reference guide….” — E. Svanoe
Ammo & Ballistics 6 contains data and illustrations on virtually every sporting cartridge sold in the USA. This latest edition covers 200-plus cartridge types from .17 Mach 2 up to .700 Nitro Express.
At the request of our readers, we provide select “Deals of the Week”. Every Sunday afternoon or Monday morning we offer our Best Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, optics, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
NOTE: All listed products are for sale to persons 18 years of age or older. No products are intended for use by minors.
⏺ Good reloading kit at significant savings, cheap shipping
Midsouth Shooters has a great deal on the Hornady Lock-N-Load Classic Reloading Kit. You get pretty much everything you need to start handloading — an excellent single stage press, powder dispenser, digital powder scale, hand priming tool, powder trickler, chamfer/deburr tool, powder funnel, and case lube. You even get Hornady’s 9th Ed. reloading manual. All this is now just $299.99, a $71 savings. This Reloading Kit ships for FREE. And, to celebrate Midsouth’s 53rd Anniversary, for other purchases of $53 or more you get shipping for fifty-three cents with promo code 53BDAY.
⏺ Scope and rangefinder for hunting — combo for under $200
Here’s a good and ultra-affordable scope/LRF combo for a hunter on a tight budget. The Buckmasters Rangefinder and Riflescopes combo brings the performance of Sig Sauer Electro-Optics within reach of every hunter. The 3-9x50mm scope has a Bullet Drop Compensation (BDC) reticle with holdover dots out to 500 yards. The SIG Sauer LRF 1500 Laser Rangefinder offers fast-ranging performance with red illuminated display optimized for low light hunting. If you don’t need a scope, you can get the 6X Buckmasters LRF 1500 Laser Rangefinder for just $129.99 at MidwayUSA.
3. EuroOptic — Trijicon Riflescope Clearance
⏺ Trijicon makes excellent optics, now with HUGE discounts
Trijicon scopes are some of the best value riflescopes on the market. The have good glass, are sharp, and very reliable. And now, EuroOptic is offering Trijicon riflescopes at crazy low clearance prices. With discounts exceeding 50% off, this is likely the best deal you’ll ever see on scopes of this quality.
4. Sportsman’s Warehouse — Winchester .22 LR Wildcat, $229.99
⏺ Removable lower receiver, Picatinny rails, good trigger, great price
Here is a fun little semi-auto .22 LR rifle at a crazy low price — $229.99 at Sportsman’s Warehouse. The Winchester Wildcat takes Ruger 10/22 mags, and has some great features, such as field-removable lower receiver, ambidextrous controls, integral Picatinny rails and rear barrel access. It has a good trigger and shoots well. In many respects the Wildcat beats the Ruger 10/22 while costing considerably less. The lower receiver assembly is easily removed from the upper assembly by pushing a button — no tools required.
⏺ Rugged backpack includes First Aid Kit and survival tools
This rugged EVERLIT Survival Backpack includes a 68 oz. Hydration Bladder. In addition the pack comes complete with 23 tools and accessories including compass, flashlight, glow sticks, multi-function pliers, saber card, paracord, poncho, shovel, thermal blanket and a well-equipped First Aid Kit! You get all this for $69.99 at Amazon — a pretty amazing deal. This is a great product for hikers and hunters. Choose either tan or black backpack for the same $69.99 price.
⏺ GREAT Deal on rimfire silhouette steel target 20-Pack
There are few things as fun as plinking with a .22 LR Rimfire rig at steel targets. It’s fun for kids and adults alike and right now you can grab a 20-ct pack of RIMFIRE animal targets in assorted sizes and shapes. They are 1/5 size and made from A36 steel plate. IMPORTANT: These small steel targets work great for rimfire shooting, but should NEVER be used with centerfire rifle cartridges.
⏺ Good, comprehensive, many powder options, with color illustrations
Everyone should have a good hard copy reloading manual. With a print manual, you can bookmark key pages, quickly compare various powder/bullet combos, and you don’t need a computer in your loading room. We like the Lyman Reloading Manual because it includes all major powder makers. New cartridges in this 51st Edition include 224 Valkyrie, 22 Nosler, 24 Nosler, 6mm ARC, 6mm Creedmoor, 6.5 PRC, 6.5 Weatherby RPM, 6.8 Western, 300 PRC, and more. Choose Hard Cover for $28.99 or Soft Cover for $26.99. Both are good deals.
8. Amazon — MTM Four-Section Ammo Carrier, $29.49
⏺ Great for storage AND transport for rifle and pistol ammo
This MTM ammo crate has been very popular with our readers. The MTM AC4C Ammo Carrier features four lockable polymer ammo cans in a fitted, four-slot 23.5″ x 11.3″ x 7.5″ carry crate. This makes it easy to haul four full ammo cans. Actual purchasers have raved: “Moments after I received this storage box set I ordered another. Very well-built and great design — a steal at the price.” The system includes four lockable, O-Ring 11.3″ x 7.2″ x 5″ ammo cans (AC30T) for multi-caliber ammo storage. The crate even includes tie-down points for transport in a cart or ATV. This is on sale now at Amazon for $29.49 or MidwayUSA for the same $29.49 price.
9. Springfield Armory — 3 Extra Mags and Range Bag Free
⏺ Good deal if you are shopping for a compact pistol
Here’s a cool bonus promotion if you’re shopping for a new defensive handgun. Now through August 31, 2022, Springfield Armory is offering three (3) extra magazines plus a carry range bag with every striker-fired handgun purchase. This Gear Up 2022 Promo applies to ALL Springfield Armory Hellcat, XD, XD-MElite and XD-S® Mod.2 handguns.
10. MidwayUSA 1008 1″-Diam Hi-Viz Green Target Dots, $4.66
⏺ Get over 1000 Hi-Viz target dots — great for pistol and rifle
These 1″-round Hi-Viz target spots from U.S. Ballistics stick on nearly any surface. Fluorescent, lime green in color, these targets are highly visible, and also contrast dark bullet holes well. Right now this target pack, with 1008 stick-on target circles, is just $4.66 at MidwayUSA, a 53% savings! We use these target dots for rimfire and centerfire practice.
Are you a High Power or F-Class marksman looking for official bullseye paper targets? Here are bulk sets of 25, 50 and 100 targets from Creedmoor Sports. All these can can be used for general practice, fun matches, or official sanctioned events. Choose the official 200-yard SR target with all scoring rings (X,10,9,8,7,6,5), priced at $49.95 for 50. For long-range practice, try the NRA Official 600-yard High Power Target ($58.95 for 25ct), or the Official “Full Face” MR-65 500-Yard F-Class Target ($31.95 for 50ct). Creedmoor also offers a variety of Repair Centers, including the 300-Yard SR-3C Target Repair Center ($34.95), or the 600-yard MR-1 Target Repair Center ($64.95). These target centers can be used on top of full targets, or by themselves for practice on smaller target frames.
Creedmoor Sports also offers match-grade spotter discs. These are used to mark shot locations. They are offered in three diameters: 1.5″, 3.0″, and 5.0″. In addition, you can purchase the spindles used with spotter discs along with orange Golf Tees also employed to mark shots. These are placed in the shot holes by pit workers.
Frankly for practice, we recommend a target cam, or ShotMarker system.
Tumblers and walnut/corncob media are old school. These days many shooters prefer processing brass rapidly with an ultrasonic cleaning machine. When used with the proper solution, a good ultrasonic cleaning machine can quickly remove remove dust, carbon, oil, and powder residue from your cartridge brass. The ultrasonic process will clean the inside of the cases, and even the primer pockets. Tumbling works well too, but for really dirty brass, ultrasonic cleaning may be a wise choice.
Our friend Gavin Gear has evaluated an RCBS Ultrasonic cleaning machine using RCBS Ultrasonic Case Cleaning Solution (RCBS #87058). To provide a real challenge, Gavin used some very dull and greasy milsurp brass: “I bought a huge lot of military once-fired 7.52x51mm brass (fired in a machine gun) that I’ve been slowly prepping for my DPMS LR-308B AR-10 style rifle. Some of this brass was fully prepped (sized/de-primed, trimmed, case mouths chamfered, primer pockets reamed) but it was gunked up with lube and looking dingy.”
UltimateReloader.com Case Cleaning Video (7.5 minutes):
Gavin describes the cleaning exercise step-by-step on UltimateReloader.com. Read Gavin’s Cartridge Cleaning Article to learn how he mixed the solution, activated the heater, and cycled the machine for 30 minutes. As you can see in the video above, the results were impressive. If you have never cleaned brass with ultrasound before, you should definitely watch Gavin’s 7.5-minute video — it provides many useful tips and shows the cleaning operation in progress from start to finish.
Ultra Dry Necks After Ultrasonic Cleaning — Some Suggestions
The Ultrasonic cleaning process gets cartridge brass so “squeaky clean” that increased force may be required to seat your bullets, or they may “grab” as they go in the necks. To reduce bullet-seating effort, you may benefit from adding a little dry case lube inside the case-neck before loading (use a nylon brush). Another trick is adding a teaspoon of Ballistol lube to the cleaning solution. That provides a trace lubricant inside the necks, but does not interfere with powder ignition in any way.
The latest Gen2 RCBS ultrasonic cleaning machine has a large 6.3-quart capacity. That’s nearly 100% larger than the first generation machine in Gavin’s video. The Gen2 machine, $406.99 on Amazon, features a second ceramic heater and transducer to better clean brass cases and firearm parts. The LED is easily programmable, and the timer can be set for up to 30 minutes of cleaning. The original 3.2 quart-capacity RCBS ultrasonic machine, as shown in Gavin’s video, is still available for $180.72 at Midsouth Shooters.
When shooting groups at long range on paper it can be difficult to distinguish which bullet holes belong to a particular sequence of shots. If, for example, you shot three 5-shot groups at 600+ yards on a paper target, you would have 15 bullet holes on the target (assuming no misses). But at that distance it would be difficult to see the holes on target (even with a spotting scope). Accordingly, when you inspected the target up close, it would be hard to tell which shots belonged to which group. You might have a vague idea, but couldn’t be sure, without a target camera recording the shot sequence.
Here is a method to separate multiple shots into specific groups so you can better evaluate your load and shooting skills. The trick is pretty simple — mark your bullets with a color from a Sharpie or other felt marking pen. If you are shooting three 5-shot groups, mark five with red, five with green, and five with blue (or purple). Then, when you inspect the target, you can identify the group placements by the colors that appear on the paper.
Round Robin: Using colors you can shoot “Round-Robin” to evaluate seating depths, neck tension, or other variables without having the shot order (and barrel heating) affect group sizes unequally. For example you might have three different neck tensions, each marked with a different color on the bullets. Then shoot Red, Blue, Green in that sequence for five total shots per color.
Smart Tip to Show Colors More Vividly
If the bullet inks are not showing up on your target paper clearly, here is a simple trick that can make the colors “bleed” to be more visible. In your range kit, bring some alcohol solution along with some Q-tips. Then dab the shots on the paper target lightly with wet Q-Tips. Here is the front of a target before and after application of alcohol:
Forum Member NewbieShooter explains: “Dabbing a bit of alcohol on the bullet holes with Q-Tips makes the color pop a bit… especially on the back side.” See below:
In short order you will see the colors spread into the paper, clearly marking the shot holes by distinguishing colors. If you were shooting a dark bullseye, view the the BACK side of the target to see the colors on a light background.
Credits: Bullet Tips photo by Forum Member Dave Way; Target photos by Forum Member NewbieShooter; Story tip from Boyd Allen.
Probably the most popular centerfire rifle round in the Western Hemisphere is the .223 Remington and its metric match, the 5.56x45mm. Though many folks use “.223 Rem” and “5.56×45″ interchangeably, there are some meaningful differences in specifications for the original .223 Rem and the 5.56x45mm cartridge, as adopted by the U.S. military and NATO armies. The default chamber throats are slightly different and the .223 Rem is rated at 55,000 PSI vs. 62,366 PSI for the 5.56x45mm.*
.223 Rem vs 5.56x45mm — Key Differences
There is a truly outstanding, very thorough article on the subject, published by LuckyGunner.com.** This involved extensive testing, with pressure monitors, of 5.56x45mm ammo in .223 Rem chambers. Those tests revealed the peak pressures. Here is one of the ammo test charts:
NOTE: “The observed chamber pressure for Federal XM855 5.56mm ammunition in a .223 Rem chamber exceeded .223 maximum pressures, but not by a massive amount. The ninth shot (the red line) was an underpowered cartridge which exhibited significantly lower velocity and pressure than the other rounds, so it was excluded from the average velocity and pressure numbers for this chamber.”
And if you’re curious, LuckyGunner also fired .223 Rem ammo in a 5.56x45mm NATO-chambered AR15 rifle. As you would expect, the peak pressures were significantly lower, but the .223 Rem ammo still cycled the semi-auto AR-platform rifle perfectly well:
UltimateReloader.com Explains .223 Rem vs. 5.56x45mm
To explain the key differences between the .223 Rem and 5.56x45mm cartridges our friend Gavin Gear of UltimateReloader.com has created a very thorough 12-minute video. This covers the cartridge specifications and explains key considerations for hand-loaders. Gavin also addresses the oft-asked question “Can I shoot 5.56x45mm ammo in my .223 Rem chamber?” Gavin’s video is definitely worth watching. In fact, this is one of the most popular videos Gavin has ever created — it has been watched nearly 4.5 million times on YouTube.
What Exactly Is the 5.56x45mm NATO Cartridge?
The 5.56×45mm NATO is a rimless bottle-necked intermediate cartridge family standardized by NATO with development work by FN Herstal. It consists of the SS109, SS110, and SS111 cartridges. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries.
Bullet diameter: 5.70 mm (0.224 in)
Maximum pressure (EPVAT): 430.00 MPa (62,366 psi)
Maximum pressure (SCATP 5.56): 380.00 MPa (55,114 psi)
Case length: 44.70 mm (1.760 in)
Rifling twist: 178 mm or 229 mm (1 in 7 in)
Parent case: .223 Remington (M193)
Ammo-Maker Federal Premium Compares .223 Rem and 5.56x45mm
Here is a video from ammo-maker Federal Premium explaining the difference between .223 Remington and 5.56x45mm NATO. Federal states that you may experience excessive pressures when firing a 5.56x45mm in a standard .223 Remington chamber:
One leading gunwriter has addressed the question of shooting 5.56x45mm ammo in .223 Rem chambers. He advocates caution (for more info, SEE pressure tests by LuckyGunner.com):
“I have received a slew of questions — many from first time AR-type rifle buyers — about the .223 Rem and the 5.56×45 mm NATO cartridges. Can I shoot 5.56×45 mm NATO in my .223 and vice-versa? Are these the same cartridge?
Externally, the two cartridge cases are identical. The main differences are that 5.56×45 mm NATO operates at a higher chamber pressure (about 60,000 PSI versus 55,000 PSI on the .223 Rem.) and the 5.56’s chamber is slightly larger than that of the .223 Rem. Also, the throat or leade is longer in the 5.56×45 mm chamber. What does this mean? You should not shoot 5.56×45 mm NATO out of a rifle that is chambered in .223 Rem [with a standard short throat]. And be aware that some .223 Rem ammunition will not reliably cycle through some AR-style .223 Rem rifles, but it usually does. As a matter of fact, I have not encountered any difficulty with current .223 Rem. loads cycling through a 5.56 mm AR-style rifle.” — Mark Keefe, Editor, American Rifleman
* According to the official NATO proofing guidelines, the 5.56×45mm NATO case can handle up to 430.0 MPa (62,366 psi) piezo service pressure. The U.S. SAAMI lists Maximum Average Pressure (MAP) for the .223 Remington cartridge as 55,000 psi (379.2 MPa) piezo pressure with deviation of up to 58,000 psi (399.9 MPa). The chamber for military 5.56×45mm NATO has a longer throat prior to the bullet contacting the rifling which results in lower pressures when firing 5.56×45mm NATO ammunition. If 5.56×45mm NATO is used in rifles chambered for .223 Remington the bullet will be engraving the rifling when chambered. which can increase pressures past SAAMI Max levels. NOTE: The C.I.P. standards for the C.I.P. civilian .223 Remington chamber are much closer to the military 5.56×45mm NATO chamber.
** The full-length LuckyGunner article is well worth reading. It even provides specifications for a number of .223 Rem reamer types, and compares the original .223 Rem, the 5.56x45mm NATO, and the modern .223 Wylde chamberings.
