07-09-2018, 06:02 PM
A5BLASTER Wrote:If you think the crown needs reworking then it's best to do it because it will always bother you.
Probably best to tear it down to parts and
1 lap the upper
2 bed the barrel or shim it to upper
3 torque it to 5 pounds higher then you have it now
4 make double triple sure the gas tube isn't binding up on any of the parts
5 take good measurements and make sure the gas block is being seated over the port correctly and locktite the screws once they are torqued down to spec
6 install handguard and double triple check it isn't contacting the gas block or gas tube, try to flex it and see if you can make them touch if they do, find a different handguard.
7 check that your mags are somehow striking the bullet when loading and changing your bullets seating depth.
8 if your cleaning the barrel often stop let it get dirty and see if it settles in ( my tow jp barrels are like this they won't group unless they are dirty).
Just a question but what upper are you useing is it a mil spec or is it a nice 7075 t6 billet, could be the barrel is just to heavy if it's a mil spec upper and causing the group issues.
Just some food for thought hope it helps sir.
Edit to add, measure the gas port size and double triple check their isn't anything blocking flow in the port.
Blaster thanks for the help! I did lap the face of my reciever with Brownells lapping tool. I bedded the barrel with sleeve retainer; the fit was pretty tight before hand. Here is the upper I have. It looks to be inline with what you listed:
https://www.midwestindustriesinc.com/MI-...frs-15.htm