Broken 6mmAR Bolt

[LRRPF52]

The only way to get the cmmg grendels to come in at ar15 weight standings is this.

Replace all the internal parts that you can with either titanuim or aluminum parts. Remill the bcg to be really lowmass or have a custom shop build you a aluminum or titanium bcg in a lowmass configuation.

Then take the lower and mill out the side plates of the mag area.

Take the upper and have a custom shop mill in some slots along the length of the upper to drop weight their. Or have a custom shop mill you a lowmass style upper to replace the cmmg one with.

Then loss the buffer and spring it comes with throw in the very best lowmass buffer and spring system made. Slap a adjustable gas block on the barrel after having the barrel re profiled down too .600 and the gas block area re profiled to .625 and then put on a titanuim adjustable gas block and a titanuim flash hider.

Throw on the most stripped down basic stock they make and add a 10 round mag half loaded top it off with a red dot and bam a 7 pound cmmg grendel rifle.

Are you could I don't know safe a bunch of money buy a chronagrah and work up sane loads and never break a bolt.

I have a few irons on the fire right now but I'm gathering materials to do a bolt breakage test.

Handloads will be set at 55k. And we going to see how many rounds it takes to break it.

If you're using a bolt with the mass of the LR-308 and CMMG Anvil bolt, you will depart from the 3:1 rule of carrier mass-to-bolt mass if you reduce the carrier weight.

That can/will result in sluggish unlocking unless you gas it hard, and you still run into the issue of sluggish cyclic rate in the initial rearward inertia.

This is one of the problems with the Remington Model 740 and 7400 semi-auto hunting rifles.

The CMMG Anvil in Grendel also has a bit more mass than even a .308 bolt because of the reduced bolt face width for a narrower cartridge.

Compound that with the fact that you have 10gr less of case capacity and lower working pressure than .308 Win., and you are really setting up for needing to make some gas system changes if you want to have a reliable action.

I think for a 6mm AR, the CMMG Anvil makes a lot of sense where you aren't worried about bolt thrust, since the 6mm AR has more bolt thrust than 6.5 Grendel due to the bottle neck effect on back pressure.