FGMM 175 having ejector marks in my AIAT

[gun-ho]

Finally took my AT 308 20 (factory LW 1:12) and 260 26 barrel (from MH, 1:8) to the range, shot some factory ammo and handloads, much more accurate than my old savage. However, I've noticed a new issue.

From the really mild loads (IMR4895 42.2 OR IMR4064 41.5, 0.02 off lands), my brasses are showing ejector marks, even for 175 FGMM (average 2430 FPS per chrono) and Hornady 168 match (not chrono-ed). It's not a brass issue since all 4 (FC+Hornady+Norma+Lapua) are involved. Per google some of the brand new brass can have this problem due to too much headspace but FGMM and hornady are factory ammo. No primer crating or difficulty lifting my bolt etc.


FGMM 175 @ 2430


Hornady 168 match


Brand new Norma brass with 185 juggernaut, 42.6 varget, CCI 200, 0.02 off lands @ 2430


Brand new Norma brass with 178 HPBT, 43.6 varget, CCI 200, 0.02 off lands @ 2510


Brand new Lapua brass with 175 SMK, 42.2 IMR 4895, CCI 200, 0.02 off lands @ 2480[/QUOTE]

 

[gun-ho]

Brand new Lapua, 175 SMK, IMR 4064 41.5, CCI 200, 0.02 off lands @ 2450


Brand new Lapua, 139 Scenar, H4350 42, CCI 200, 0.02 off lands @ 2750


Bolt face

Are all the loads over-pressure? This is really confusing...Any thoughts?

 

[former naval person]

Sharp edges on the ejector hole in the bolt face can cause this.

 

[KYpatriot]

That doesn't look like a raised mark indicated brass flow, it looks more like a cut. Sharp edge on the ejector hole sounds right.

 

[agbm]

Really strange, does your ejector have any spring tension at all? If the bolt face is not completely smooth and you have the raised edge in the ejector hole/spot as stated above the circle on the brass would happen. Just contact maker and send the rifle/bolt back to be repaired.

 

[Rprecision]

Its hard to tell from the pictures, are the marks raised like flow or just marks left in the brass? Is the bolt cutting any off?

I have seen this on factory FGMM in my AE MKIII, the difference is that is very soft brass. But the primers show no signs of problems,

As another measure of pressure, all of your primers look very conservative, clean radius on them.

 

[gun-ho]

The marks are not raised. Just sharp cuts. May be sharp ejector edge is a good explanation. I have been loading hotter loads without any problem. Thanks!