High Pressure Issues (Help)

[hylander]

M77 .308 Varmint
Sierra 150SBT, 42.0 4064
WLR primer, 1X CBC and 1X PPU brass, FL sized in Redding dies.
Case lenght trimmed to spec
OCL 2.750

I'm at the lower end of the load, however I am getting completely flattened primers and very sticky bolt.
Rounds chamber easy, head space correct, .050 of the lands.
Scale was checked with RCBS check weiths
What am I missing ?

[emy]

What are you using for scale, also check case length and crimp , maybe too much

[TexasJackKin]

What are you using for scale, also check case length and crimp , maybe too much

^^^^^ This, check case length, if to long it can be "squeezed" in the throat of the chamber, and a little goes a long ways, when it comes to pressure.

[hylander]

^^^^^ This, check case length, if to long it can be "squeezed" in the throat of the chamber, and a little goes a long ways, when it comes to pressure.

Already done, both are correct

[DSMeyer]

Time to check the case volume, see if these particular cases are built to the heavier NATO/military specs.

[Bumslie]

Post pics of cases?

[krwada]

Everything you say should not have this effect. PPU brass will not do this. You are trimming to spec.

The only other thing I can think of is ... Once you think you have properly charged a round, dump the contents into the pan of the scale and measure it. There may be something about what you are doing that may inadvertently be overcharging.

The other thing to do is to set the OAL of your round to a published OAL. Yes, this will set the round back and create a longer jump. How did you measure the chamber OAL? It could very well be that you may think you are 0.050" off the lands, but in reality are really jammed into the lands.

It is far better to start with a SAFE round before trying to go whole hog on accuracy.

Double check everything ... Assume NOTHING.

[baih777]

your case OAL dimension may be correct but did you check the shoulder of the case ? case headspace.
take one of your resized cases and see if your rifle will chamber the case with no resistance. no primer, no powder, no bullet.

[Wrangler John]

My experience firing a considerable quantity of PPU brass is that it runs a bit hotter, more akin to military brass, than commercial brass such as Nosler and Hornady. Back off a little and everything should go back to normal.

[Rbutler]

just curious why you are loading under min load?

Hodgdon has it as 43 minimum for the 150gr nos BT. Loading under min can cause its fair share of issues.

Also is it a custom barrel? 2.8 to the lands seems close for a factory rifle since that the COAL of most factory ammo.

[xfer42]

What twist rate?
Tighter twist will result in higher pressure.

[bruce381]

this load is telling you too hot no matter what books say back off 1 grain or more. your gun is telling you listen to it.

[highpower790]

this load is telling you too hot no matter what books say back off 1 grain or more. your gun is telling you listen to it.

A couple months ago I helped a fellow calguner develop a hunting load using the same components,with the exception of a 165gr Sierra Gameking.
He wanted to start at the bottom of the load spectrum,but I suggested something closer to the middle to eliminate 50% of load development.He settled on 40gr IMR4064.A phone call later said his rifle shoots nice little holes exacetly where he wants them.By the Sierra book which we used ,40gr is 3.5gr less than max.

[Carsgunsandchics]

My experience with PPU brass is they tend to have a loose primer pockets. And check the size of the flash hole because my last three bags of brass have been varied in size.

[bruce381]

A couple months ago I helped a fellow calguner develop a hunting load using the same components,with the exception of a 165gr Sierra Gameking.
He wanted to start at the bottom of the load spectrum,but I suggested something closer to the middle to eliminate 50% of load development.He settled on 40gr IMR4064.A phone call later said his rifle shoots nice little holes exacetly where he wants them.By the Sierra book which we used ,40gr is 3.5gr less than max.

and this helps this guy how?