Mike Venturino recommends using magnum primers, for bp loads. Personally, I have not seen much difference between the two in actual use. Until going to fairly large capacity cases...ie: 45-70, etc. Then, I did notice a bit more consistent ignition. I have since switched over to magnum primers exclusively, for .45-70 hunting loads. The exception being pistol-caliber cartridges, ie: .44-40, .45 Colt, etc. Then, I just go with a standard primer.
I expect that powder granulation may have some influence on the choice, too. Coarser powder granulation requiring a bit more flame to get it going. I also found this to be the case with Pyrodex Cartridge powder. Not so much with RS. Or: Fffg and Ffg. Can't comment about Triple 7 in large rifle cases. Since I primarily use it in pistol caliber loads. Then, a standard primer sets it off just fine.
If you can get your hands on some magnum primers though, you will likely find them to offer the most consistent ignition, overall. But, if standard primers are all you have right now...I would still use them.
Al
ps: Snider Shooter offers sound advice. Much of my experience is similar to his. Your rifle will soon tell you which it prefers.