If a load is shooting great would you keep it if it showed primers starting to flatten. Or back it down at the cost of a little accuracy

I would back off a bit. Drop it by .5 grains and see if the signs go away. I doubt that you would loose much accuracy at all.

Flat primers could be a lot of things. Federals flatten no matter what. Take a set of Mics if you have some and measure the case expansion at the webbing. You need to compare it to a new case however. If it expands more than .003" to .005", she is getting hot. Even this isn't the end all be all of measureing pressure. Along with that, primers flattening, and noted bolt lift, I make that decision.

I never let primer flattening alone tell me not to shoot it. Primer peircing is a different matter. Primer flattening with heavy bolt lift, then I back off.

+1----Well put.

If I remember correctly you like single shots, so you may not have a bolt rifle. But sticky extraction is pretty close to heavier bolt lift. Tom.

It is a sinle shot and it is a little harder to pop open. What and where do you classify the webbing on a cartridge.
I am still having trouble with this barrell, it went from 4" groups to 2" but thats it.
It wont do any better and the 3 loads it did the 2" groups with were hot loads. 2.5 gr lower it opens up bad.
But I have only tried two powders. W 760 and Varget. Any idea which other powder I should try.

4064 is an option. Varget burns dirty unless its high pressure.

What cartridge?? Are you shooting a light or a heavy for caliber bullet?? And what is the twist rate of the firearm??

I had a single shot NEF that was a 223. I could not get it to shoot-period. Then I had the throat measured, and it was unbelievably long. I think they made them to shoot the military heavies(just a guess).

By pop open do you mean automatic extraction of fired casings?? Or do you mean the action is hard to open?? I am not sure how a hot load would make the action hard to open?? I shoot some hot loads in my Encore's, but it does not affect the opening of the action, but it does affect the extraction. Tom.

7mm-08 I am trying 2 different bullet weights 120,s and 140,s
Both shot the best 2" groups on hot loads. .02 off the lands 1-10 twist
When I mean hard to pop open , the release bar becomes hard to push to pop open.
This same gun with my hornet barrel will group 1" all say long sometimes even better than that. This barrell will not do it. 4" with factory ammo. I think I will sell the barrell. I think I am done with it.

Ridge hit another point I forgot. If you are only able to get 3 fires before the primer seating has little to no tension, its overpressure.

Breakopens can be difficult.

try 39 grns of varget.im loading barnes 140 tripple shock and nosler accubonds with 39 grns. savage bolt youth model and it is a very good load. 3 shoots one good clover leaf.