45-70 GOVT. Small primer pocket, SRM?

[ozmosis]

Well with the price of 45-70 hitting almost $40 a box of 20 for 405 grain Remington I am setting up for reloading the Govt. I have a box of 350 grain Buffalo Bore Ammo that I shot half of in Alaska when I lived there, So I opened the box yesterday and had a surprise. The cases have a small rifle primer pocket and I am guessing that its a Small Rifle Magnum. Any one know if I can use a SRM instead of Large Rifle primers without serious issues in my load data? All my other 45-70 brass takes a LR primer which is listed in my loading books.
I did a search and did not find any info on the subject.
Powder will be H322 and projectile will be 425 grain Pile Driver Jr and 405 grain Lead Flat nose.
Thank you in advance.

 

[huntershooter]

Using SRM primers should increase pressures.
I WOULD NOT substitute the magnum primers for any load approaching maximum.
I would use the SR primers and start load development below listed maximum. Additionally, H322 does not require a magnum primer.

 

[Maj Dad]

Mag primers may or may not increase pressures, but like huntershooter says, don't use them off the bat in max loads. Work up your loads normally with them, and they'll do fine. The bigger spark doesn't necessarly make your specific load of powder burn hotter/faster/longer - it just makes a bigger spark and ignites the charge thoroughly. I have always wondered why the term "magnum" was applied to primers instead of rating them by brisance, but then, we have a 17 HMR, 22 Magnum and 222 Magnum, too. Not to mention a Magnum of Piper Heidsieck, which is definitely prefereable to a Demi or Piccolo...