Fact or Fiction: Small vs. Large Pistol Primers in .45 ACP

Fact or Fiction: Small vs. Large Pistol Primers in .45 ACP

I don't know if you've noticed, but several of the major ammunition companies are loading some of their .45 ACP ammo using Small Pistol rather than Large Pistol primers.

So what's the difference in performance between .45 ACP handloads using Large Pistol versus Small Pistol primers?

I had always assumed there couldn't be too much, or shooters would notice and avoid the Small Pistol primer factory loads, but I'd never taken the time to experiment and compare ballistic data.

Some Winchester, Federal, and CCI factory loads have appeared with Small Pistol primers. The Winchester headstamp includes an "NT" marking, which I believe indicates nontoxic (lead-free) primers. Some Federal factory loads also use a similar coding. CCI/Blazer, Speer, and other Federal brass loaded with Small Pistol primer pockets simply have the ubiquitous ".45 ACP" or ".45 Auto" headstamp.


Well, you ask, "So what?"


Obviously, it must be safe to do so or they wouldn't risk it. But it can surely play hob with your reloading routine. Trying to force fit a 0.210-inch-diameter (and highly energetic) disc into a 0.175-inch-diameter primer pocket can cause a significantly emotional event if it ignites. A friend of mine handloads on the automated Dillon 1050 progressive tool, and after experiencing several startling "pops," he now carefully examines any fired .45 ACP cases he picks up at the range and stores and reloads his Small Pistol primer brass separately.


It's just another example of why segregating your cases—by headstamp, number of times fired, etc.—is a good rule to follow.

My most significant brass recovery coup occurred at an InterMedia Outdoors writers' conference. Local range club members volunteered as range officers for the conference and usually divvied up fired cases from each day's shooting sessions. But the morning after several new .45 ACP pistols had been thoroughly wrung out, empties remained scattered all over the recovery tarps. I asked one of the early rising range members about it, and he responded, "It's all Blazer brass with Small Pistol primers. Nobody wants it." After I convinced him it could be reloaded with no problem, we quickly gathered up and split more than 2,000 bright and shiny cases. I still haven't loaded all of mine yet.

Large vs. Small


For this exercise, I chose five propellants and assembled several boxes of target loads using Zero 200-grain, swaged SWC lead bullets, Blazer cases with Federal 100 Small Pistol primers, and Federal cases with Federal 150 Large Pistol primers. I also used a couple of boxes of hotter handloads that utilized CCI and Speer brass primed respectively with CCI 500 (Small Pistol) and 300 (Large Pistol) primers topped with Hornady 185-grain XTPs. They were loaded with Ramshot Zip powder.

I load all of my .45 ACP ammo with Hornady Custom-Grade New Dimension dies. Unlike most "no lubricant needed" tungsten carbide sizing dies, Hornady's sizer die features a titanium nitride coated insert. To date I've loaded thousands of rounds and, if I clean it occasionally, expect it'll last many thousands more.

I've found that seating a swaged lead bullet, being softer than a cast or a jacketed one, requires a bit more casemouth flaring. But don't overdo it—just make sure the mouth clears the bullet base enough to avoid scraping lead as it is seated.


Most reloaders skip cleaning the primer pockets. I almost always do clean the pockets, and not wanting any adverse variable to affect the results of this evaluation, I did so when preparing these test loads. If I'm priming more than 100 cases, I typically use a handheld tool with a magazine tray; fewer test load groups are usually primed with an old RCBS ram-prime die arrangement. However, I always gauge primer seating depth by "feeling" the case head with my finger to assure they're at least flush and, preferably, two- or three-thousandths below flush.

https://www.shootingtimes.com/files/2014/08/small_or_large_pistol_primer_45_acp.jpg
After shooting hand loads with both Small Pistol and Large Pistol primers, the author found that their results compared favorably.

Redding's 10-X mechanical powder measure usually dispenses very precise charges. It handled Trail Boss, Red Dot, and the other disc or flake propellants—with one exception. I wanted to vary charge weights by just a few tenths of a grain, and IMR 700-X just wouldn't "throw" close enough. So I individually weighed each charge to obtain the desired result.

I seated the swaged lead bullets first (COL of 1.24 inches) and then ironed out the casemouth flare in a Hornady taper crimp die to obtain a casemouth diameter of 0.470, +/- 0.001 inch.

I chose my Heckler & Koch USP Expert .45 ACP pistol to perform the range work. The magazine holds 10 rounds, so I could load five each of the Small Pistol and Large Pistol primer test loads and fire comparable groups back to back. The pistol also has excellent iron sights that my aging eyes can still discern well enough to shoot quite accurately.

As you can see in the accompanying chart, the results of the selected loads compare quite favorably. I prepared at least three batches of each target load varying the propellant charge weights as my evaluation of the velocity data (average and standard deviation values) and group size suggested.

I also checked in with one of my industry contacts to find out, if possible, just why they chose to switch from Large Pistol to Small Pistol primers in some of their .45 factory loads. We discussed the actual quantitative and chemical variables between their Large Pistol and Small Pistol primers.

https://www.shootingtimes.com/files/2014/08/small_or_large_pistol_primer_45_acp_1.jpg

Because the SAAMI specs do not dictate primer configuration, my source summed up the situation by simply saying, "Today's primer technology is so much better than before, a Small Pistol primer is now actually more suitable for the .45 ACP cartridge."

Practically speaking, you don't need to avoid handloading .45 ACP brass that have Small Pistol primer pockets. Just be sure to keep them separated from the Large Pistol primer pocket cases.

Reloading Dies

Reloading dies are where the magic happens. You'™ll need a set of dies for each separate caliber that you want to handload. Most sets run 25 to 50 dollars, although match-grade rifle dies and carbide handgun dies — which eliminate the need to lube cases before sizing — can cost a bit more.

Excellent dies are available from RCBS, Lyman, Forster, Dillon Precision and Hornady (pictured here). RCBS also offers a list of dies for obsolete or very obscure cartridges, with makes life easy for vintage gun nuts like me.

Handheld Priming Tool

Many single-stage reloading presses come with a case-priming assembly, but in my experience they tend to be finicky and seat primers a little crooked. A good hand-held priming tool is well worth the expense, and will pay for itself in time saved.

Many single-stage reloading presses come with a case-priming assembly, but in my experience they tend to be finicky and seat primers a little crooked. A good hand-held priming tool is well worth the expense, and will pay for itself in time saved. Hornady makes one I personally use the most, but other manufacturers of reloading equipment offer quality tools as well. makes one I personally use the most, but other manufacturers of reloading equipment offer quality tools as well.

Reloading Manual

While you can find a lot of the information online, there'™s no substitute for a good reloading manual. It will have detailed instructions and vast amounts of data, helping you master the finer points of handloading. Very importantly, a good manual is your guide to safety procedures, and will help you keep your eyeballs intact and all the digits on your hands.

Most bullet manufacturers offer a loading manual, but they are typically specific to that manufacturer'™s projectiles. My favorite all-around manual is Lyman'™s 49th (current) Reloading Manual. It offers extensive data for a broad variety of projectiles and propellant types in a very easy-to-access format.

Powder Scale

Powder scales are used to measure and charge prepped cases with volumetric scoops. Some folks will tell you to start with an assortment of powder scoops, but I personally believe that'™s an antiquated and potentially dangerous method.

A good scale typically costs 70 to 120 dollars, enabling you to precisely measure gunpowder. Charging your empty cases by mass, is much more accurate than by volume. After you'™ve referenced your loading manual and chosen a charge weight, simply trickle powder into the scale'™s pan until it reads as desired, then transfer the charge into an empty case. This process is safe and precise, while also producing super-consistent loads.

RCBS (pictured here), Hornady, Dillon Precision and Lyman make excellent-quality units.

Reloading Press

If reloading dies are where the magic happens, the reloading press is the cauldron in which it is brewed. The dies are screwed into the top of the press, and the shell holder attaches to the top of the ram. As you cycle the handle, the ram travels up and down, sliding the cartridge case in and out of the dies; where it will be resized, flared if needed and the bullet seated.

Single-stage presses are the most common type, and are most applicable to this discussion. They hold only one die at a time, and thus will perform only one action at a time. Available models vary from compact, handheld versions, up to massive high-torque presses — some designed specifically to handle the extra-large demands of cartridges such as the .50 BMG. Prices range from 60 dollars up to several hundred. RCBS (pictured here), Lyman and Hornady make my favorite single-stage presses. Any of their various models will serve well, but bigger presses offer more torque and are easier to cycle, especially when loading big magnum cases.

Powder Trickler

While I trickled gunpowder into the pan of my scale with a teaspoon for years, using a good trickler is far easier and much less trying on your patience. After dumping a charge just short of complete into the pan of your scale with a volumetric scoop or a spoon, just twist the knob on the powder trickler and drop a few grains of powder into the scale to complete the charge.

If you have the extra dollars, get Hornady'™s Lock-N-Load Quick Trickle, which has a good-size powder reservoir and dual-speed knob — enabling complete, fast trickling straight from the trickler.

Case Die Lube

Before sizing-down expanded cartridge cases, you'™ll need to lube them so the cases don'™t stick in the sizing die. You can apply lube by hand; or by rolling cases on a pad impregnated with lube, or by spraying them down with lube suspended in a carrier of alcohol. I use them all, and some application methods are better for some cartridges than others. If I had to pick just one, I'™d use a spray lube.

Just line up the cases on a cookie sheet or a sheet of cardboard, and spray them lightly. Then roll the cases a half-turn and spray again. As soon as the carrier has evaporated, the cases are ready to size.

Who makes the best case lube? Right now, I use Royal Case Die Lube most frequently. It'™s not available at most gunshops; you'™ll likely have to order it online.

Shell Holder

Easily the most overlooked, yet absolutely necessary bit of reloading equipment, the shell holder is a small, 5-dollar tool that fits into the top of your reloading press'™s ram and holds the base of the cartridge as it runs in and out of the various dies.

Like reloading dies, shell holders are cartridge specific — to an extent. However, many cartridges share the same parent case, so in several instances one shell holder will work for numerous calibers. For example, the shell holder for .30-06 cases works for .25-06 Rem., .270 Win., .308 Rem., .243 Win. and a whole slew of others — even including the .45 Auto.

Reloading die manufacturers list and sell appropriate shell holders for the various calibers. If possible, I like to use shell holders made by the same company that made my dies, but that'™s not critical — shell holders are machined to exacting tolerances shared by all manufacturers.

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