Need some help: Too slow then pressure

[JollyRoger]

Here’s a few pics of my brass. When I say blown primer, I mean it came out of the case after firing.

 

[TaperPin]

I’m also reading up on carbon rings… I haven’t cleaned this barrel at all. Is that something that could cause this issue?

Yep.

 

[Caseknife]

Here’s a few pics of my brass. When I say blown primer, I mean it came out of the case after firing.
View attachment 870005

View attachment 870006

How did that second case get extracted without shearing off the portion that flowed into the ejector? That is raised enough to show a shadow, should have been all smeared off. Maybe something wrong with headspace?

 

[JollyRoger]

How did that second case get extracted without shearing off the portion that flowed into the ejector? That is raised enough to show a shadow, should have been all smeared off. Maybe something wrong with headspace?

How did I get the case out? I just ran the bolt, it was a hard lift for sure but I just ran it and it came out. Headspace seems fine, I think? I can remeasure it to be sure

 

[Harvey_NW]

Sounds like a combo of less than optimal brass, and Tikka action showing pressure around published max. Lapua SRP is probably your best bet. The problem with the carbon ring theory is if that's the issue you're going to be scrubbing that barrel out after every match and you'll get velocity migration as it fouls up. I choose the easier option of jumping a little bit further to stay out of fouling and doing load dev on a completely fouled barrel and don't worry about it.

 

[JollyRoger]

Sounds like a combo of less than optimal brass, and Tikka action showing pressure around published max. Lapua SRP is probably your best bet. The problem with the carbon ring theory is if that's the issue you're going to be scrubbing that barrel out after every match and you'll get velocity migration as it fouls up. I choose the easier option of jumping a little bit further to stay out of fouling and doing load dev on a completely fouled barrel and don't worry about it.

I think it’s likely I’m dealing with a few issues for sure.

 

[wind gypsy]

Shorter suppressed guns seem to get stiff bolt lift from bolt thrust quicker as the chambers get a lot of hot gas in them. I'd clean the chamber at least and give the lapua brass a try.

I'm having similar issues with a 24" CTR barrel trying to reach power factor with 140s and h4350. Going to just shoot 144s i think. RL26 or N555 is another option i have but I'd rather keep burning through my pile of H4350.

 

[JollyRoger]

Shorter suppressed guns seem to get stiff bolt lift from bolt thrust quicker as the chambers get a lot of hot gas in them. I'd clean the chamber at least and give the lapua brass a try.

I'm having similar issues with a 24" CTR barrel trying to reach power factor with 140s and h4350. Going to just shoot 144s i think. RL26 or N555 is another option i have but I'd rather keep burning through my pile of H4350.

I’ll give the cleaning a try. I knew at some point I’d want to upgrade to better brass (Lapua, Alpha, Peterson, others?) and will likely try some N555 powder soon to see if I can get this thing to either the 140s faster, or to shoot the 147s better without pressure issues

 

[Harvey_NW]

I’ll give the cleaning a try. I knew at some point I’d want to upgrade to better brass (Lapua, Alpha, Peterson, others?) and will likely try some N555 powder soon to see if I can get this thing to either the 140s faster, or to shoot the 147s better without pressure issues

Peterson tends to show pressure quicker IME, go for Lapua or ADG. Haven't tested Alpha yet but will be soon when my 6 Creed is finished.

 

[wind gypsy]

ADG cases are smaller capacity. For velocity i think you're going to want lapua or Alpha.

Oddly enough, i'm reloading some norma factory ammo brass too and found it takes about 0.2 grain more h4350 to hit same velocity as lapua brass so may be a bit larger in capacity but I think the ass end is softer and seems to show pressure signs earlier.

 

[JollyRoger]

ADG cases are smaller capacity. For velocity i think you're going to want lapua or Alpha.

Oddly enough, i'm reloading some norma factory ammo brass too and found it takes about 0.2 grain more h4350 to hit same velocity as lapua brass so may be a bit larger in capacity but I think the ass end is softer and seems to show pressure signs earlier.

My sweet spot for the AI was once fired Norma brass, 41.5gr of H4350, and a 140 ELD-M seated 0.020” from the lands. It was just too slow in this 22” Proof