False Positive Pressure Signs

[Rflshootr]

You're better off.

 

[RockyMtnMT]

Factory ammo, Hornady, shot from CA Ridgeline.
Heavy bolt lift, to the point I needed to bring a rubber mallet to the range to tap bolt open. As the rifle heated up, it would get worse. Groups went from 3 shots touching to 12" by the 6th shot.

Looks like the right throat issue of CA causing excess pressure. I have heard that they have fixed this, but don't know. Accuracy I'm guessing is a bad barrel. Or just very poorly put together.

 

[Mike Matteson]

Glad to be enlighten. Never stop learning. I have had ejector mark's, but that was to much pressure. Never seen anything like this.
Thanks again.

 

[Calvin45]

There seems to be a plague of bad bolt faces slipping out to the world lately. I've had no fewer than 5 conversations about this in the past 2 weeks alone. So I figured a public service announcement was necessary. Some of you may remember an article I wrote many years ago describing how to read pressure signs. I make mention of this issue in that article. Here it is for those that haven't read it:

Understanding Pressure :: Primal Rights, Inc

Reading pressure is a required skill that all shooters must have. Whether you are shooting factory ammunition or your own handloads, you absolutely must be able to detect and interpret pressure signs on your fired brass.

www.primalrights.com

I just received a new rifle that had the false positive issue, so I wanted to document it here. Folks, this is why it's so important to use a smith that will catch issues like this before they get out to you. These days, Taylor Stratton at Stratton Custom Rifles in Delta Colorado does my work... and one of the main reasons I chose him is that he will properly evaluate and fix each action he builds on as a matter of course. Many smiths rely on the action manufacturers to catch issues, and they simply do not.

The issue at hand is this:

My brand new rifle, was demolishing my cases... making it appear as I was running a massively over-pressure load. The action I'm using is a brand new Lone Peak Fuzion. The action did not have the ignition properly timed, nor did any of the other burrs or issues get fixed. (was not built at SCR) I have vast experience with 22 creedmoor, so I knew that 40gr of H4350 behind a 70gr berger was not a hot load, and was not over pressure. This is further evidenced by the fact that the primer is not cratered, not flat, and there are no other defining signs of pressure beyond the massive ejector wipe.

I've run into this issue several times before, and while it is sad that a top level action such as a Lone Peak Fuzion exhibit this problem... it's very obvious what is going on. When the hole for the ejector was drilled, the bolt face was not cleaned up afterward, leaving a massive burr around the ejector hole. The proper fix is to fully indicate the bolt in true, and then run a cleanup cut on the bolt face. However, this needs to be done before the barrel is installed, as it will alter headspace. So, in order to fix it... I use a special cylindrical stone, and twist it across the surface by hand.

The stone I use to fix the issue.

Here you'll notice the burr is removed, as evidenced by the shiny ring around the ejector pin hole. Not an easy area to work in manually.

I've seen this on many actions in my career... and it's a shame, because all would be needed is for the final bolt face cut to be performed AFTER the hole is drilled for the ejector... then a quick twist in the ejector pin hole with a deburr tool or 45° abrasive point to handle the ID burr. The most unpleasant part about this is the fact that a great many shooters do not have the experience to tell false positive pressure, from actual pressure. So they end up chasing their tail in frustration for a long while before reaching out to me for help. Then once this problem is discovered, it's not trivial for someone without much experience to fix this on their own.

Hopefully this will help any of you that might encounter this in the future.

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Read the article…very good information but one thing I'm not following or clear on; is it your assertion that the brass case is part of
The load bearing chain regarding rearward thrust? I've never heard that anywhere else before but suspect I've just muddled something and am not hearing you right.

But if I am…what are your thoughts on nickel plated brass in high pressure loadings? Like federal premium or something. Would such loads place greater strain upon the bolt face and lugs as the nickel is slick as baby and won't be binding up against the chamber walls at all really?