Dirty gun = Pressure issues?

[greyghostnw]

do you trim your brass? Do you push your shoulder back properly? Make sure your brass is trimmed within .002 of each other 10-15 thousandths less than max in chamber. Have you taken fire control apart like plungers out as well sized brass till bolt handle just has a slight touch before it falls to bottom? Should measure around .002 less than fired case. If your not full length sizing at all its harder on your brass and bolt lugs and can create hard bolt lift. The list goes on. Case base swells if you let it get away…. Consistent redundant practice equals results on paper. Good luck.

 

[General RE LEE]

Filthy cans dropping chunks of carbon in a bore when bumped at the range or field will spike pressure.

I clean my Banish Backcountry ~ 300 rounds and I like to run a few Hoppes patches every other range trip. I also brush out the chamber every few hundred rounds to get the carbon ring.

I seldom go after copper unless there is a consistent change in groupings.

 

[Neilbob]

Bumping this thread just because the same thing happened to me the other day. During load workup for a new 7MM Sherman Short barrel, I worked up to pressure (slight ejector mark and a little sticky bolt lift) with N555 and 175 grain ELDX using virgin ADG brass. I figured I'd gain a slight amount of case capacity once fired, but I still dropped 0.5 grains and shot a few more groups that didn't show any pressure signs. Thought I was good to go and loaded up quite a few. Then after a few range trips, I got significant ejector mark and difficult bolt lift. I cleaned the gun, backed down another 0.5 grains, and also seated the bullet another 0.01 off the lands. I was already 0.030 off. Everything seems happier, but I'll keep an eye on it.

 

[wind gypsy]

Bumping this thread just because the same thing happened to me the other day. During load workup for a new 7MM Sherman Short barrel, I worked up to pressure (slight ejector mark and a little sticky bolt lift) with N555 and 175 grain ELDX using virgin ADG brass. I figured I'd gain a slight amount of case capacity once fired, but I still dropped 0.5 grains and shot a few more groups that didn't show any pressure signs. Thought I was good to go and loaded up quite a few. Then after a few range trips, I got significant ejector mark and difficult bolt lift. I cleaned the gun, backed down another 0.5 grains, and also seated the bullet another 0.01 off the lands. I was already 0.030 off. Everything seems happier, but I'll keep an eye on it.

Loading close to pressure signs on a fresh barrel and virgin brass typically means you'll be well into pressure once the barrel is seasoned and brass is on subsequent firings.

 

[Tanner]

Found this doozy of a thread after some research and wanted to chime in and pick some brains.

My tikka 6 CM is about the most consistent rifle I’ve shot in the last 10 years. Just consistently hammers with every bullet I’ve tried.

I’ve got a well proven load of 109 ELDMs over 39.5gr of H4350 that makes about 2870. Today that same load was showing pretty noticeable pressure issues that were way out of the norm for it. My first inkling was be a super dirty barrel as it’s been shot 100% suppressed for about 350 rounds, so I went ahead and ran 2 rounds of a foaming bore cleaner down it, as painful as that was as I’m generally in the “don’t clean until something looks very wrong camp”. Kinda’ wondering if I don’t also need to grab a can of C4 and see what sort of carbon ring I’ve got built up.

Anywho, I will shoot it again soon and see what shakes out. This was a fun read!