SP vs LP

[Bullseye69]

So I've got a question aboot cases that you can get with either SRP pocket or LRP pocket.
I see Peterson cartridges has some choices for thier 243 and creedmore casings.
What is the reasoning for this?
Ive also ran into this reloading 45ACP.

 

[L.Sherm]

I believe the SRP will handle little higher pressure before the PP get to loose.

 

[Bullseye69]

Ok, that makes sense.

 

[L.Sherm]

I run Lapua SRP brass in my 6 Creed.

 

[kiwishooter]

Years ago there was an article in Precision Shooting regarding primers the small rifle primers gave more consistent impulse.
I would have to go and re read it but my perception was that small rifle primers gave more consistent ignition in smaller cases but when the powder column got longer and using different powders, some harder to ignite, the small rifle primer did not provide enough ignition, so while some case volumes worked well with small rifle primers and allowed more material around the primer pocket there is a limit to the benefit and a larger rifle primer should be used.

Are the test results from back then still valid or have primers changed? That is another question.

Tuning the load and trying both options if its available could be worthwhile

 

[Rick in Oregon]

I know one thing.....when loading .45ACP on a progressive press all set up (for years) with LPP, finding a case with the small pocket in the middle of a 1,000 round run is most disturbing to say the least.

 

[Bullseye69]

I know one thing.....when loading .45ACP on a progressive press all set up (for years) with LPP, finding a case with the small pocket in the middle of a 1,000 round run is most disturbing to say the least.

Yep, everything comes to a complete halt!!
I bet it would really suck with 45acp and spp and you get a large one.
Powder leaking out the bottom, if you weren't paying attention to how the primer didn't seat.