So my good buddy and I are working on our 22 grendel builds and struggling pretty bad at this point. Specs are as followed: aero enhanced upper, jp enhanced bolt, 20" barrel 7 twist, +2 rifle length gap system with JP adjustable gas block. Measured the shoulder of factory hornady brass at 1.209 on 6.5 grendel and stayed true after necking down to 22 cal. The OD of the case neck is .250 before firing. We've tried h4895, cfe223 and varget with 75gr eld. We had to take the barrels to our local smith (who didnt do the chambering) to polish the chamber because it was so rough the brass was getting stuck and would not cycle. Was also leaving some pretty bad rings on our brass. Also, the shoulders on h4895 loads are getting blown out .014, with varget it's getting blown out .006 but the velocities are suffering pretty bad. The SD's are phenomenal with all the powders but we are getting gnarly ejector Mark's on virgin brass. The fired brass ID of the neck is also very tight, not letting a bullet slide into the neck like fired brass should. Keep hearing claims everywhere of the 22 grendel getting over 3100 easy with 75gr elds and very minimal pressure signs. Wondering what we are doing wrong, or if it's a bad chambering job.
- Thread starter pmccolley24
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Any pics of the rings on the brass? If the od of the brass is .250 that means that the neck thickness is .013" which doesn't seem to be thick but without knowing what your chamber measures I don't know for certain. What does the case neck measure after being fired? If you can't slide a bullet in the fired case then it sounds like the neck needs turned
Working on getting pics and measurements right now, the guy who did these barrels claimed that necking down hornady brass to .250 OD is a no turn neck for his chamber. Will get pics and measurements for you here soon though
Ok so I couldn't get a clear pic of the brass for some reason but the rings did polish out after polishing the chamber. The OD of the brass pre firing is .250, post firing is .2535 and the ID post firing is .223. Was told to use .250 bushing for the neck and it would be a no tun neck. Not quite sure on his chamber specs. Could explain why we are getting brass stuck in the chamber, to the point we have to use a hammer to get the bolt to pull back. Doesn't explain extreme pressure signs at the lower velocities we are getting.
That's our pressure signs at 2800fps, brass not even getting out of the chamber. Sounds like an undercut neck if we can't even get a bullet in the case on fired brass. Maybe it's getting stuck and that's what's causing over pressure??
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If shoulders are moving forward .014", and you're getting bad ejector marks, that's two pretty big clues telling you that you've bumped the shoulders back too far. Forget measuring from factory Grendel ammo, that has nothing to do with the chamber in your rifle. Bump the shoulders back no more than .004", based on fired brass from your chamber with hot loads.
If your Varget loads are only blowing shoulders forward .006", you probably are at pretty low pressure with those loads, and are getting false pressure signs from the excess headspace. Those ejector marks are likely a sign of headspace issues, not pressure. I'd guess the same about whichever load was used in your brass picture above, low pressure but bad headspace.
It also sounds like your chamber necks are too tight; you'll need to have them opened up or else turn case necks. Personally I'd leave the chamber alone and turn necks, but the fact that you had bad rings in the chamber doesn't speak well for the guy who did your work. I'd be pretty disappointed with that myself.
