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6.5 CM Pressure question

Jayhawkhuntclub

Sergeant of the Hide
Full Member
Minuteman
Jan 26, 2019
469
223
I'm not too worried, but I'd like a second opinion.
Loaded some 147 gr ELD with H4350, 1/2 gr steps from 37.0 to 41.5 in never fired Starlne SRP cases. Rifle is an RPR. OAL is 2.83", Fed AR Match primers.

At 41.5, I averaged 2698 fps; sd was 6 and group was 0.585" for 5 shots at 100.

Only concern is I did get a few fairly mild ejector marks, very mild cratering, mild flattening of primers, no stiff ejection.

SO is there any reason to be concerned about the ejector marks? I also had an ejector mark on brass at 39.5 (1 of 5 cases) and one at 41.0 (2 of 5).

Now this load is still 0.3 gr under Hodgdon's data. And from what I'm seeing, most guns have no issues up to 42.0 gr. and slightly beyond.

My guess is the marks have to do with being virgin brass. What do you think?
 
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Can you measure case growth from new to fired, if new brass grows much over .004" on the first firing, false pressure signs are in order. A friend tried some starline 6 creed brass and we deemed it softer.
Your firing pin slams the case forward to start, it goes off and slams back into the bolt face at the same time trying to kick the primer out.
I want to say no on pressure, but let someone else with this combo chime in.
 
41.5 is my H4350 load with 147's out of my RPR in Prime brass Fed210m primers and a 24" Proof M24 all stainless barrel. 2700 FPS. Load and go.
 
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Don't worry too much about the ejector marks. It seems to be an RPR thing. Mine does it on most shots and i'm no where close to my pressure point. As far as the primers, fed primers are very soft and tend to give false signs often. You should be fine.
 
Milo 2.5 gave you good advice. Also remember book data is only a reference. I wouldnt advise to "not worry about it". Plenty of help around here to find a solution. My guess is Milo is spot on fwiw.