Pressure Signs

[918v]

I would like to present a Winchester .308 case:





As you can see, it has been fired.

The load is 185 Berger LRBT, 43.5grs Varget, CCI BR primer, 2.900" OAL.

The rifle is a TRG-22.

It was cold today, I could see my breath.

Low pressure, right?

Wrong.






While the primer looks normal, if you look real close you see an ejector swipe starting at the "W".

I couldn't believe it.

So I fired another shot and got the same thing.

That load is too hot for my rifle. Sucks, cuz it only makes 2600 FPS. I guess there's no advantage in shooting them over SMK.

 

[gvanhyning]

How was the bolt lift? The primer doesn't show signs of pressure. I had ejector swipe on some new loads for my 6x47 Lapua but no other signs of pressure. I ran a dry chamber mop in the chamber and the pressure signs went away.


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[mtrmn]

I'm sorry if I'm totally ignorant or something, but I see no signs of high pressure here. I saved the primer pic and blew it up. In my opinion, the polished area could just be a purely mechanical scrape from normal metal-to-metal contact with a spring-loaded ejector. The ejector could have sharp edges or even a tiny burr? With the normal-looking primer and the velocity figure you quoted I just don't read any problems into this......but you are the final judge and only you have hands-on familiarization with this.
I'm sure I'll draw fire for this, but personally I draw the line when the case actually has metal removed (scratch/scrape) or I see the imprint of the bolt face (ejector hole) beginning to show up.

 

[damoncali]

It's hard to tell from a photo, but I can't see an ejector mark there - looks more like a case that rubbed against the bolt face.

 

[918v]

The bolt lift was normal. It's hard to tell from the pics, but if you look real close it is plainly obvious the case flowed into the ejector tunnel and got shaved when the bolt unlocked.

 

[BuzzBoss915]

I think your first comment is probably true and in that case, it's hard to say what the exact dynamics would be going on within the chamber? In other words, the scrape mark on the case head could be a red herring, the sooty neck is an indication that you didn't have enough pressure to seal in the chamber and these were probably full length resized with the shoulder set back a few thousandths? Also, a cold ambient temperature and low resultant velocity adds up to a potentially low pressure round.

Now tell us about the rest of the story. Have you fired this load before, on a warm day? Was this part of a load work up? Do you have other examples, loaded at the same time? A lot of people say to disregard primers in a gas gun but I seem to be looking at a spent primer that isn't lying? So, what else you got? BB

 

[918v]

This was a twice fired case, neck- sized in a Lee collet neck die. The shoulder was bumped .002" using a Redding body die. I shot this load in warm weather and in cold, but at 2.925" OAL. I shortened it a bit to see if my ES would improve.

 

[17874]

It looks fine to me, but it's your rifle.

 

[918v]

Everything looks fine except the ejector marks.

 

[Ol Rob]

No one should judge your level of commitment to safety. But if you saw my brass you would freak out.
Rob

 

[BuzzBoss915]

Here again. If you have your mind made up, why ask for opinion? Or maybe you aren't asking?

What you are calling *ejector marks, I always get on my Howa 1500. It's the EXTRACTOR indent you might worry about, although I'm not sure of what type is used in the TRG? But on a Model 700, it's a circular impression on the case head.

The only clue I see, based on your photo, is a sooty neck. How do you explain that? BB

 

[HodgdonExtreme]

It's your rifle and your ass on the line, so load it the way you like.

To me, the soot running most of the way down the shoulder indicates relatively low pressure. I'm used to seeing Varget leave soot no further down than ~1/2 way down the neck.

Also, in my opinion, very little in the way of conclusions can be drawn by judging primers.

 

[thespecialist]

Blew that case head up until it was 8" wide and could just start to make out a very light wipe from where the bolt face rotated the ejector across the brass. Over pressure it's not, not even close. But, like someone else said, it's your gun so back off if you want.

 

[918v]

Here again. If you have your mind made up, why ask for opinion? Or maybe you aren't asking?

What you are calling *ejector marks, I always get on my Howa 1500. It's the EXTRACTOR indent you might worry about, although I'm not sure of what type is used in the TRG? But on a Model 700, it's a circular impression on the case head.

The only clue I see, based on your photo, is a sooty neck. How do you explain that? BB

I haven't made up my mind.

The marks are circular impressions made by the edge of the ejector tunnel where the brass flowed in and was cut.

My concern is why I'm getting them at all given the other signs or lack thereof.

 

[HodgdonExtreme]

I haven't made up my mind.

The marks are circular impressions made by the edge of the ejector tunnel where the brass flowed in and was cut.

My concern is why I'm getting them at all given the other signs or lack thereof.

Frankly, if those came out of my rifle, I wouldn't be the least bit concerned.

Still, if you're concerned, why not load a few rounds with the charge backed down to ~43gr, 42.5gr and maybe 42.0gr... And see if/when your "ejector mark" goes away?

I had a similar thing happen to me with my TRG42 in 338LM. I was working up a load with 300gr SMK and Retumbo. I started at 87.5gr or so and worked up to 91.5gr. Saw that 90.5 seemed to be the ticket. That's when I noticed caseheads ALL (even the 87.5gr loading) had slight (and I mean SLIGHT) circular ejector marks on them. They were not raised, and I could not catch a razor blade on them. There were no other indications of pressure; the bolt lifted smoothly and nicely, the primers had a nice radius on them, the velocity was inline with the loading manual, the casenecks were even sooty like yours are. Still, I decided to load some cartridges with reduced charges. I only went down to 83gr, but even there I was still getting the slight circle mark.

Because I was getting 2665fps with 90.5gr, the rifle shot great, and the manual indicates a max load of 94 (a 4% increase over my charge), I said fuck it and stopped worrying about it. It's never bitten me in the ass, the rifle still shoots great, and the brass lasts and lasts and lasts - though it still leaves the mark every time. I might point out a 30 minute run in stainless media erases any vestige of the mark.

 

[Deadshot2]

I haven't made up my mind.

The marks are circular impressions made by the edge of the ejector tunnel where the brass flowed in and was cut.

My concern is why I'm getting them at all given the other signs or lack thereof.

All brass is not created equal. I see this regularly with my Remington when I'm shooting different brass. For me, the Winchester brass is more prone to the "ejector half moon" until it's been fired several times. I'm surmising that the brass is work hardening some more and after 3x or more firings it's hard enough to not yield as much.

Lapua-hardly ever do I get that mark unless I'm way "out of bounds". If I saw soot on the neck like on your case, and a primer that is still as "round" at the edges, I'd go for some more powder. Hodgdon lists 44 gr as the max for Varget using a 190 gr bullet. I'm going to go out on a limb and say that you have some more speed left.

If it were my rifle I'd go up in increments of .3 or so until I saw some more flattening of the primer as long as your bolt lift doesn't get difficult. I used to be terrified of flat primers and ejector wipes until I found that primers of different brands flatten sooner than others and that brass might "mark" differently from brand to brand. Sometimes the same brand in the same batch using the same load would show different case head marks------or not.

As for the 185 LRBT's, the difference won't necessary show up with chrono readings but on the actual target downrange. Those bullets took 'flying lessons' before they left the factory and are nice performers. You'll definitely benefit from the greater BC on them vs the SMK's At least I did when I was able to get, and afford, the 185 gr Bergers.

 

[918v]

Maybe it's a heavy bullet / fast powder thing. It doesn't do it with 168 /175.

 

[Deadshot2]

Maybe it's a heavy bullet / fast powder thing. It doesn't do it with 168 /175.

Very possible but the soot makes me believe you aren't getting enough pressure.

If you want to try a powder that really does a good job with the 185's try RL-17. I had a good run with the 185 Juggernauts and RL-17 until both became scarce. I'm now finding the RL-17 and stocking up on it. Now if I could only find some Juggernauts