January 04, 2011
By Lane Pearce
By Lane Pearce
The author compared handloads with both primer sizes for velocity and accuracy.
A lot runs through my mind when I'm thinking about the subject of handloading. Often those thoughts lead to new and intriguing projects. Some recent questions that have popped up and which led to some fun handloading and shooting exercises are: Does using Small Pistol primers instead of Large Pistol primers in .45 ACP loads make any difference? Is there a better way to form .257 USM wildcat cases? What causes leaky or cratered primers? Here is what I discovered while trying to answer those questions.
Large Or Small Primers In .45 ACP? Years ago, Hansen Cartridge Co. imported ammunition made in Yugoslavia. The firm offered most of the popular loadings, including .22 LR, 9mm, .357 Magnum, .40 S&W, .45 ACP, .223 Remington, 7.62x39, etc. All of the centerfire rounds were Boxer-primed brass cases, so reloading was a snap--with one exception. The first batches of .45 ACP arrived onshore loaded with Small Pistol primers.
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That wasn't a big deal for the casual handloader, but if a few cases with Small Pistol primer pockets were inadvertently mixed with thousands of cases with the usual large pockets, the volume reloader had a severe headache. Decapping and sizing go smoothly, but crushing a Large Pistol primer into the smaller pocket has to be at least exciting and could be quite hazardous. Hansen's supplier quickly switched to using Large Pistol primers in subsequent lots of .45 cartridges.
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In the past I have reloaded both types of .45 ACP cases, and though I was wary that my loads might not perform as well with Small Pistol primers, I never had any problems. Years later, an industry contact said he had tested .45 ACP rounds with Small Pistol primers and compared the results to the ballistic performance of "normal" rounds using Large Pistol primers. He concluded that Large Pistol primers were not necessary and that the .45's ballistic performance might even be improved by using Small Pistol primers.
At one of the 2009 InterMedia Outdoors editorial roundtables, I picked up some once-fired brass from the pistol range. We were shooting Para USA pistols and Speer Lawman ammunition. Apparently no one wanted the .45 ACP hulls because they all had Small Pistol primers. That surely didn't bother me, and within a half-hour or so, I had 1,000+ sparkling, once-fired cases stashed in the back of my Trailblazer.
Better Way To Form .257 USM Cases? If you've read my column for a while, you know that I like to experiment with wildcat rifle cartridges. My most recent endeavor was melding the .270 WSM and .25 WSSM into what I call the .257 USM. Basically, I concluded that if you replaced the front end of the .270 WSM with that of the .25 WSSM, you might have the optimum .25-caliber short magnum.
The two Speer .45 ACP cases are identical except for the Small versus Large Pistol primer pockets.
I decided to assemble some test loads using both types of cases and compare velocity and accuracy results. Here's what I found out.
Using several propellants, two brands of Small and Large Pistol primers, and some distinctly different bullets, I loaded up four moderate loads. As the accompanying chart shows, velocities dropped less than 3.5 percent, and half of the test loads grouped significantly better.
Lesson learned. If you turn up some .45 ACP brass with Small Pistol primer pockets, don't turn it down. If you don't want it, send it along to your reloading editor.
Both parent cartridges are excellent performers. The .270 WSM has achieved well-deserved recognition, while its super-short cousin hasn't, and probably never will. I figured the longer neck and less abrupt shoulder of the .25 WSSM would reduce a necked-down .270 WSM's overbore capacity, i.e., essentially it would "unimprove" the resulting wildcat case, hence the USM acronym.
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.45 ACP Handloads Compared Bullet Powder (Type/ Grs.) Case Primer Velocity (fps) Extreme Spread (fps) Standard Deviation (fps) 25- Yard Accuracy (in.) Clements 170-gr. Cast SWC HS-6/ 8.5 Speer Fed. 100M 871 71 27 1.60 Clements 170-gr. Cast SWC HS-6/ 8.5 Speer Fed. 150M 893 55 15 1.40 Hornady 185-gr. HP/XTP ZIP/ 6.7 Speer CCI 500 894 71 19 1.05 Hornady 185-gr. HP/XTP ZIP/ 6.7 Speer CCI 300 926 91 27 1.70 Clements 195-gr. Cast SWC AA No. 5/ 8.5 Speer CCI 500 896 57 13 1.30 Clements 195-gr. Cast SWC AA No. 5/ 8.5 Speer CCI 300 919 79 19 1.40 Hornady 230-gr. FMJRN True BLue/ 7.0 Speer Fed. 100M 779 41 10 1.10 Hornady 230-gr. FMJRN True BLue/ 7.0 Speer Fed. 150M 790 48 12 1.45 Notes: Accuracy is the average of four, five-shot groups fired from a sandbag benchrest. Velocity is the average of 20 rounds measured 6 feet from the muzzle of a customized Colt 1991 with a 5-inch barrel.
This once-.270 WSM case has been reformed, annealed, and loaded for final fireforming into the author's latest wildcat experiment, the .257 USM.
Several friends joined me in this project, but all but one opted for simply necking down the .270 WSM to .25 caliber like several others had already done. RCBS made the special reamer to cut the chamber and provided all of us with reloading dies. My buddy and I soon discovered it was quite difficult to reform .270 WSM cases without trashing a large percentage. He eventually sent his rifle back to our gunsmith and had it rechambered to the "standard" wildcat format. Not me. I was going to make mine work.
I carefully reworked three boxes of brass but ended up with only two boxes of usable cases. Between folds in the necks, collapsed shoulders, out-of-round and slightly warped necks that required extensive neck turning and trimming, I lost a third of the reworked cases.
There had to be a better way.
I recalled that RCBS had supplied me with form and trim dies on past occasions when I needed to make 7x61 Sharpe and Hart cases from 7mm Remington Magnum and, more recently, reform .300 Winchester Magnum brass into .308 Norma Magnum, so I called engineer Steve Koch to discuss this new challenge, and he assured me they could remedy my problem.
Several months passed before a regular die box arrived. It contained two threaded form dies. I gathered up two boxes of once-fired R-P .270 WSM brass and 20 new Norma cases. Lightly lubing each case, I ran them into the die with the larger diameter neck to first reshape the shoulders. Next, I used the second die with the smaller neck port to reduce the case neck diameter. Then I resized them in the original full-length sizer die and trimmed them to achieve the required case dimensions.
After extensively cold working the brass, I annealed the necks and shoulders, quickly quenching them in water. When they were thoroughly dry, I loaded them with a slightly reduced charge (50 grains) of IMR-4064 and 117-grain Hornady roundnose bullets for final fireforming. The heavy bullets were seated long to accommodate the Montana Rifle Co. Model 1999's extended short action.
When I'd finished, I had lost only two cases. Both were rejected because I'd applied too much lube when reforming them, and the dented shoulders did not iron out when the rounds were fireformed.
What Causes Leaky Or Cratered Primers? While shooting some handloads recently, I encountered a couple problems: leaky and cratered primers. The first condition occurred with a box of .308 Winchester match handloads that were definitely not too hot because the chronograph data was quite normal and consistent. I noticed the second condition when I assembled my first handloads to see how they compared to factory ammo performance in a military-surplus 1896 Swedish Mauser.
Handloads with leaking or cratered primers indicate a problem that must be identified and corrected before using the component or firearm again.
As you can see in the photo, several primers leaked. I called the supplier, and after I confessed to purchasing them at least 20 years ago, the technical guru suggested the cups probably cracked when I seated the primers due to the effect of long-term stress corrosion.
"Lane, they can't last forever. Use fresh ones from now on," he said.
As the other photo shows, the primer in the right 6.5mm SM case looks okay, while the one on the left is significantly cratered. This may be caused by several factors. If the load is too hot, the primer cup will flow around the tip of the firing pin. Or if the firing pin hole in the boltface is too large (or the pin is a bit short), the same result can occur. The rifle's h
eadspace can also be too great, which will allow the primer to be partially ejected from the pocket when the round is fired.
It usually pays to pay attention to the condition of the cases.