Slightly Flat Primers?

[TX_Diver]

Awhile ago I did an OCW test across a wide range of charges and eventually settled on the load I have now. Wondering if I didn't miss some pressure signs back then though so looking for another opinion.

When I did the OCW it was pretty cold so I was leaving the ammo inside, then shooting, looking for pressure signs, coming inside and loading up a new magazine, then going back out, shooting, etc. What I missed during that was comparing the appearance of the primers to one that was unfired...

Yesterday I shot a bit and since it was warm (~35) and I wasn't doing load development I took the entire ammo box outside as I normally would. At the end of the day I happened to look at the primers next to some unfired primers and realized that I may have missed some (now fairly obvious) flattening of the primers with the reloads when I was doing my OCW test.

Load is a 77gr SMK in 1x LC 19 brass w/ 24.0gr of N140. The VV app lists 24.7 gr as the max (book = 2657 fps, I got 2772 at 24.6gr). Sierra lists 22.7gr as max (book = 2620 fps, I got 2597 at 22.8gr). These loads at 24.0gr were at 2710 fps when I originally did the OCW test back in November. Rifle is a T3x Lite w/ 22.4" barrel. I am cutting the barrel down to 18" shortly so at that point I'll need to re-evaluate obviously if I lose a bunch of velocity.

From all that I'm interested in opinions on the primer flattening shown below. The left column (single row) was 22gr of N140 with a 75gr ELD-M in LC18 brass. The right 2 rows was 24gr of N140 w/ a 77gr SMK in LC19 brass. I'm guessing I should back off a little further to 23.5 gr or so of N140 (I was getting 2642 fps at 23.4gr) but wanted to at least get a second opinion.

Regarding the other marks on the brass I believe those were there. The last time I shot I took a sharpie and marked the brass anywhere it had an indent, ding, scratch, etc. across 10 round to make sure that they were from the original firing (presumably a semi-auto). I was not getting any new ejector or bolt swipe marks from my gun.

 

[Mulyhuntr]

What primers?

They don't look concerning to me. Ejector swipes on brass are a better indicator of pressure, especially if using primers like CCI400s, which have thin cups and flatten easily.

 

[willfrye027]

Sometimes I get flat primers from a certain brass/primer combo. I would not sweat it too much but the safest assumption would be that it’s near max. Fwiw, in my tikkas I usually see an ejector mark first, then a heavy bolt. I back off a little from the ejector marks at a minimum. They seem to show up pretty clear in my 3 tikkas.

 

[EdP]

I agree with the above in that I don't really see anything significant, and in the absence of other more reliable indicators, it does not look like a problem. Since you are very close to max from VV and over max from Sierra, I'd keep a close watch for pressure signs if you shoot that load at higher temps.

 

[Vern400]

Bolt gun?
Don't go up on charges.
Don't let anybody borrow shells or mix guns.
Roll on and don't worry.

A warm day is 35° c, not 35° Fahrenheit. So you better really watch your butt if you do shoot on a warm day with those cartridges. I've had a 40F swing make me pull bullets on 7.62