Primer Pressure Sign?


Joshua M. Smith
September 1, 2011, 02:51 PM

I'm trying to decide whether this primer is flat enough to qualify as a pressure sign:

I'm thinking not quite.

Could be wrong.

It was a Nosler Ballistic Tip 0.323" 180 grain bullet on top of 41 grains of Varget and seated about a caliber deep.

This is a starting load. However, I fired it through my G88 "S" marked. It has a 0.323" chamber but retains the 0.318" bore.

Recoil was not hard at all, but was sharp. Reminded me a lot of a .30-30.

I had no gas blow back in my face, or any bad stuff like that.

Headspace checks out totally fine, and the rifle is in very good condition or I'd not have tried this to begin with.

The only possible pressure sign I can find is that primer -- and I'm not sure it really qualifies as flat.

I have plenty of 0.318" bullets, so if you folks think that this is indeed overpressure, it won't hurt my feelings at all. I just have to decide what to go with given the 0.323" chamber, and this is part of the process.



If you enjoyed reading about "Primer Pressure Sign?" here in archive, you'll LOVE our community. Come join today for the full version!
September 1, 2011, 03:36 PM
I don't think it's showing excessive pressure. But more importantly than the primer, how does the action feel when you extract the fired case? Is it stiff or difficult to open the bolt? Primers are not a proof positive means of guaging pressures. I get all kinds of comments about my Remington brass because the ejector ring transfer to the head is present on every single piece of Rem. brass. I don't get the imprint with Win. or Fed. brass, so even that type of sign is not reliable.

September 1, 2011, 03:49 PM
Is that primer backed out? Looks like the primer has a BOLT pattern on it, but no crater ridge on the primer.

Joshua M. Smith
September 1, 2011, 03:58 PM

It may be backed out just a bit. It was a light load.

The bolt functioned like it does with my normal loads 0.318" loads.

(This is a Gewehr 88, by the way).



September 1, 2011, 05:20 PM
Normal looking for a very light load. :)

September 1, 2011, 05:55 PM
My guess is that it is not a sign of high pressure. Your charge of Varget is 1 grain less than the starting load listed at, and regardless of the fact that you have a .318 bore, a lower pressure will allow the primer and case to slam back against the bolt face giving you the look in your picture. More normal pressures retain the case in the chamber. Make sure your chamber is free of oil.
Also indicative in my estimate is the smoking down the case to the shoulder, which in my experience shows a lower pressure load. In a good chamber, as you work towards higher pressure, the smoke line will move up the case towards the mouth as the pressure seals the case. A smoke line 1/4 way down the neck is normal.


If you enjoyed reading about "Primer Pressure Sign?" here in archive, you'll LOVE our community. Come join today for the full version!