.45-70 Small Rifle Primer

[Swampman]

I have some .45-70 brass that uses Small Rifle Primers.  Does anyone know why they made them this way?  I'm guessing it's to help prevent them from being ignited by the cartridge behind them in lever guns.

[MZ5]

I do not know the answer to your question.  I do know, however, that some manufacturers use the "wrong" size primer when they're loading complete ammunition with 'green' (lead-free, etc.) primers.  Perhaps someone has made 'green' 45-70 that way?

[Lone Star]

Frankly, I'd not use them.  There is pretty limited energy in a SRP and it may have difficulty in igniting 50+ grains of powder at cold temps.  I have no idea why they were made - why not share the headstamp to help us?



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[cooper]

Swampman, if you ever want to sell those cases, try advertising them to the Black Powder Cartridge crowd.

Those guys often use large pistol primers in the normal LR primer pocket of a 45/70 due to the lower energy of pistol primers.  Black powder is very easily ignited (much easier than smokeless) and many think that any type of large rifle primer is too strong.

[EsoxLucius]

Brass used in Buffalo Bore and Garrett ammunition has a double-recessed small rifle primer pocket intended for use with the CCI No.41 NATO military-spec anti-slamfire small rifle magnum primer.  Tim Sundles of Buffalo Bore designed this ignition system for his powerful 45-70 ammunition to reduce the chance of tube magazine detonations.  Starline was commissioned to make this brass.  Sundles made the innovation available to Garrett as well.

[Swampman]

Will normal Small Rifle primers work ok?

[EsoxLucius]

Sure.  I'd expect adequate ignition with most powders used in the 45-70.  If not, you could use a magnum small rifle primer like the CCI 450.

[Westbound]

I've got some Buffalo Bore brass that uses the small rifle primers.
I loaded a couple up just to make sure they would work before loading all of them. The both went boom and sent lead downrange.
I don't have a chrono, so I don't know if it affected velocity.

[Lone Star]

Will normal Small Rifle primers work ok?

I don't think that "sure" is a very good answer here.  In the 1980s a popular wildcat was the .22 CHeetah, a special .308 case necked down to .22 caliber and swaged for small rifle primers.  The first reports in the press were stellar, telling of the cartridge's amazing accuracy and velocity.  All was well in the summer, but as more and more owners took their rifles out in cold weather reports surfaced of poor ignition.  Small rifle primers were designed to ignite around 30-35 grains of powder, while most all top loads in the .45-70 exceed 50 grains. 

Bottom line, they may work great in hot weather, but fail in cold.  .45-70 cases are not expensive, why take the chance?


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[Swampman]

.45-70 cases are expensive IMO.  I see no reason why they wouldn't work, and in fact should produce better accuracy.  I was just trying to remember why they used SRP in them.

[EsoxLucius]

Sure was entirely appropriate when taken in the context of the post.  If one finds poor ignition with standard small rifle primers in cold weather the problem is solved with the CCI 450 or the No. 41 mil-spec primer.  Both are considered a magnum primer.  Winchester 6 1/2 - 116 primers are a bit hotter than other small rifle primers and also could be tried.