I must be a real renegade on this.....prairie dogs in Montana just don't seem to care WHAT primer I used......I grab whatever is on sale and then get as many as I can afford....Winchester, CCI, Federal, Remington, S&B etc.
To the total shock of many precision shooters, I even shoot mixed brass!!
Prairie dogs don't care about that either...go figure....
My load is no hot rod (25 gr of H335 and a 55 gr RNSP bullet) Point of impact/point of aim remains the same with ANY of the primers in my Savage Axis .223. Almost 8 thousand rounds later it still shoots AMAZINGLY well!!
As far as blowing up a rifle because you interchanged primers.....hogwash. Never seen or heard of such in over 55 years of reloading and 30 years of Service Rifle matches.
Randy
I was born and raised in western South Dakota, with the nearest prairie dog town located in the pasture south of the house. For the most part I agree with you - in the example you cited. .223 brass is surprisingly uniform. With the exception of some eastern European brass, it's all very close whether it's civilian or military.
In fact, when I lived in western SD, I often shot Black Hills Ammunition's blue box remanufactured ammo (as well as their white box factory seconds). Mixed military and various commercial headstamps were the norm, but their 55 gr FMJ would still shoot MOA and their 52 gr match ammo was still sub MOA in mixed brass.
I load .223 for both varmint ARs and for my Match AR, I haven't sorted a case in decades and my .223 ammo will still shoot 1/2 MOA loaded on a Dillon 550B (using Whidden floating tool heads, a BR3 measure and a scale to verify the charge weight). I tumble my brass now and then, and I deburr flash hole when I acquire the brass, but I haven't cleaned a primer pocket in decades.
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However, other cartridges are less consistent. Take the .22 Hornet that I use for varmint hunting here in NC, where the ranges are shorter and the neighbors are close. .22 Hornet is very accurate, a bit quieter than .223 and more than adequate for the 200-300 yard ranges that are common.
.22 Hornet brass covers a broad range of case capacity. On one end of the spectrum, Hornady .22 Hornet brass is significantly thicker walled with commensurately less water capacity. At the other extreme is Remington .22 Hornet brass. Where the case walls are much thinner and the water capacity much greater. In fact, if you use a fluffy powder like Lil Gun (which works really well in the .22 Hornet, particularly with heavier bullet weights) you'll find that lighter bullet loads that work well in the Remington brass, won't fit in the Hornady brass, even with a drop tube and swirling the powder into the case. PPU and Winchester brass both fall in the middle volume wise. As a result I sort brass accordingly into three buckets and use three different loads to load it all to the same velocity.
The .22 Hornet is also very primer sensitive. Too much brisance can reduce accuracy and significantly increase pressure. Worse, the primer options are larger, with small pistol primers also being a (very good) option. Mixing or using random primers in the .22 Hornet generally hurts accuracy and in some combinations of powder case and primer will cause either excessive pressure, and even pressure spikes with lighter loads. Will it "blow up" a rifle? Probably not, but it will abuse one, with sticky bolt, etc.
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Similarly, the 7.65 Browning / .32 ACP also has a great deal of variation. You'll hear that .32 ACP is the same as 7.65 Browning and external dimension wise that's true. However, the standard bullet diameters in Europe for 7.65 Browning is .308" while in the US the standard diameters for .32 ACP are .310", .311" and .312 (for cast bullets). What that means then is that if you put a .311" or .312" bullet in a European 7.65 Browning case designed with thicker case walls for .308" diameter bullets, it may go fully into battery in a tightly cut chamber (while other pistols with larger chambers may not have any issues). If you want to run your ammo in any .32 ACP 7.65 Browning pistol, you either have to sort the brass and select bullets accordingly, or you have to post size the rounds with European case to bring them back down to the proper external dimensions.
Either way it's a small case with small charges of fast burning powder and again primer substitution can make a big difference. Will it "blow up" a pistol? Again, probably not, but most .32 ACP / 7.65 Browning pistols are blowback operated and putting a hotter primer in a max load that was developed with a cooler primer will often increase pressure and velocity enough to result in the slide battering the frame.
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My favorite long range .308 Win load (another cartridge with a lot of potential variation in brass) uses a 175 gr RDF launched at 2540 fps with a BR2 or CCI 200 primer on a 70 degree day. If I switch to a WLR primer, using the same brass, bullet, and powder charge and lot, I'll get an increase in both velocity and standard deviation. At 100 yards I won't notice any difference in accuracy, but I will see the difference at 800-100 yards.
For example, on a 70 degree day at sea level, I can expect to need 32 3/4 MOA of elevation at 900 yards. However, an increase of 40 fps reduces the elevation to 31 1/2 MOA. That 1 1/4 MOA difference is a 12" error in elevation at 900 yards, more than enough to cause a miss on the first shot.
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Along those lines, A-Square did some tests a ways back with different primers in the 7mm Mag. They found the pressure differences across standard primers ranged 9600 psi and while the differences between magnum primers ranged 8300 psi. Overall the pressure range was 12,800 psi.
Those are significant pressure differences that you ignore at your own peril.
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The reality is that primers can be in short supply from time to time and while I normally don't have less than about 5000 of each type I use on hand, I have from time to time swapped brands and substituted primers into a load I developed with another brand.
But I don't just randomly change primers. I load up 30 rounds and then go test them for differences in velocity and standard deviation. I'll decide whether I can live with the standard deviation and make any needed adjustment in the powder charge to match my target velocity for accuracy.
In most cases it's fairly easy as I will often try different primers in load development to see if a substitution will turn a great load into a really great load. Using that test data, I can usually adjust the charge weight with that lot of powder to pretty well nail the desired velocity. If you looked at me doing the swap on the bench, you might think it was pretty random, if you were not aware of the underlying data and testing.
But you do you.
