I had trouble a couple years ago with 2 coated uppers, bought the lapping tool and valve-grinding compound and to my pleasant surprise, my groups shrunk about 2/3 to sub MOA. Recently I did a build for 6mm ARC, using one of those lapped uppers I'm getting .75 MOA on a new SS Proof 18" barrel. I'm using the 105gr Black BTHP. Needless to say, I'm a fan of lapping the uppers.
Today, I got the barrel nut wrench, and when I removed the barrel nut, I noticed the fit between the barrel extension and the receiver is extremely loose. I shimmed it and set it up with green Loctite. I also re-torqued the barrel nut to a lower torque setting. When I was trying to see what the barrel nut was originally torqued at, I stopped trying when my torque wrench went above 50 foot pounds. There’s no need to torque the barrel nut that high since you don’t have to index for the gas tube with the MWI barrel nut. I set it at 50 foot pounds. Tomorrow, I’ll take it out and see if the accuracy has improved. Edit: Accuracy with the 108 grain improved, but better is that all the groups were at a consistent point of impact, and overlapping all the groups, all shots would’ve fallen within 1.5 MOA. Average group size went down to .93
Congrats! That's not a bad improvement. It's too bad that CMMG didn't do the attention to detail that made it necessary for you to go through this process.
@@thengine7 In my experience with any new firearm, it’s a bit of a lottery with accuracy. A new Bergara B14R I just got can’t out shoot the 10/22 that I accurized. I’ll need to find an ammo that it likes. The problem with 6MM ARC is that your very limited in choices a factory ammo at the moment. Hopefully other manufactures will start to produce it.
Thanks. You can find them still, just checked. I used a search engine, WikiArms. There are plenty available, but most are selling above msrp. If you can wait six weeks, you can pay msrp and order directly from cmmg.
I have Faxon 12" , Brownells 16" and BA 18" 6ARC . I'm getting the best and most consistent accuracy with Black 105g BTHP. My 12" is Gunnee Profile so not heavy at all . I'm getting 0.91 MOA for 3 shot group . Getting about 2.2 MOA once barrel heats up . With my 18" it's a super Heavy Profile . I'm getting 1.6 MOA with 10 shot group . I've taken this out to 600 yards. I hit torso Sized steel target 5x in a row with Black 105g BTHP. The 16" Brownells has been the most inconsistent. One day its 1 moa the next day it 2 moa . It's not the best barrel in the world for accuracy but it will get the job done . Co worker has 16" Proof SS Barrel and he us getting very good accuracy and Velocity. Proof Barrels so far has the been the best barrel I've seen so far . 6mm ARC IMO is the best AR15 CARTRIDGE. The 6arc and 6.5g are true do all be all cartridges for AR15 . 6ARC would be a lot more popular if it wasn't for CV . I'm lucky I bought all my ammo when it was still under 1.50 a round . Hornady states a 24" Bolt Gun will get 2750 FPS with Match or Black and 2800 FPS with 103g ELDX. They also state with 18" Proof gas Gun barrel you'll get 2625 FPS . Which is almost on point and not too far off . I'm getting 2600 with my 18" BA . I'm getting 2400 FPS with my 12" and 2540 FPS with 16" . The 12" is my do all be all AR15 Pistol . It blows me away every time I shoot it . 600 yards and in for 12" was my primary goal and it hasn't disappointed.. I didnt really shoot for groups until 80 to 100 rounds fires through I've fallen in love with 6mm ARC
I like the cartridge, and think it’s the best caliber in an AR-15 in terms of accuracy potential and long range ballistics. Since I refit my barrel, my accuracy with the ELDM has improved to .91 inches average for four consecutive three shot groups. If I put each target on top of one another, the 12 shots fall within 1.5 inches. This is a very big improvement over how it was shooting before, and no noticeable change or strange flyers after the barrel heats. I still am considering replacing the barrel, I’d like a 21 inch HB fluted Odin, but it’s not much of a priority since I was able to get the gun to shoot as I had hoped it should. I’m traveling for work now, and just so happened to stop at the closest gun shop and what do you know, they had 6ARC ammo, Hornady black, for 28 bucks a box. Unfortunately, only two boxes, but scooped them up. Current prices that the online scalpers are selling for right now is $2.42 a round cheapest. If I get the Odin barrel, it’s going to be to test a theory I have to reduce or practically eliminate harmonic vibrations. I don’t want to give away too much, or I may find it as a product for sale (which wouldn’t be the first time). Good luck, and good shooting.
How do you like the scope position? Seems to be pretty far back. The ammo is definitely way too expensive right now. A ton of the stores are selling the ammo on auction sites instead of offering it to their customers. That way they can get more money, while not being seen to price gouge.
I set the scope position to allow for adjustment in and out of the stock to have the proper eye relief. I want to be able to shorten the stock slightly so that my son can shoot it from time to time.
Finally, somebody not blaming itself for a rifle underperforming gonna be a little bit of a👏🏼
I had trouble a couple years ago with 2 coated uppers, bought the lapping tool and valve-grinding compound and to my pleasant surprise, my groups shrunk about 2/3 to sub MOA. Recently I did a build for 6mm ARC, using one of those lapped uppers I'm getting .75 MOA on a new SS Proof 18" barrel. I'm using the 105gr Black BTHP. Needless to say, I'm a fan of lapping the uppers.
Today, I got the barrel nut wrench, and when I removed the barrel nut, I noticed the fit between the barrel extension and the receiver is extremely loose. I shimmed it and set it up with green Loctite. I also re-torqued the barrel nut to a lower torque setting. When I was trying to see what the barrel nut was originally torqued at, I stopped trying when my torque wrench went above 50 foot pounds. There’s no need to torque the barrel nut that high since you don’t have to index for the gas tube with the MWI barrel nut. I set it at 50 foot pounds. Tomorrow, I’ll take it out and see if the accuracy has improved.
Edit: Accuracy with the 108 grain improved, but better is that all the groups were at a consistent point of impact, and overlapping all the groups, all shots would’ve fallen within 1.5 MOA. Average group size went down to .93
Congrats! That's not a bad improvement. It's too bad that CMMG didn't do the attention to detail that made it necessary for you to go through this process.
@@thengine7 In my experience with any new firearm, it’s a bit of a lottery with accuracy. A new Bergara B14R I just got can’t out shoot the 10/22 that I accurized. I’ll need to find an ammo that it likes. The problem with 6MM ARC is that your very limited in choices a factory ammo at the moment. Hopefully other manufactures will start to produce it.
It's a beauty! Be proud, good luck finding one now.
Thanks. You can find them still, just checked. I used a search engine, WikiArms. There are plenty available, but most are selling above msrp. If you can wait six weeks, you can pay msrp and order directly from cmmg.
If you ever want to change barrels, try Desert Precision Gunworks.
His channel is Eagle Eye Shooting Kenny is the go to on the 6ARC buids
if you try a suppressor it may help to improve the barrel harmony
True. I have a Sandman in ATF jail, so I’ll have to wait.
I have Faxon 12" , Brownells 16" and BA 18" 6ARC . I'm getting the best and most consistent accuracy with Black 105g BTHP. My 12" is Gunnee Profile so not heavy at all . I'm getting 0.91 MOA for 3 shot group . Getting about 2.2 MOA once barrel heats up . With my 18" it's a super Heavy Profile . I'm getting 1.6 MOA with 10 shot group . I've taken this out to 600 yards. I hit torso Sized steel target 5x in a row with Black 105g BTHP.
The 16" Brownells has been the most inconsistent. One day its 1 moa the next day it 2 moa . It's not the best barrel in the world for accuracy but it will get the job done .
Co worker has 16" Proof SS Barrel and he us getting very good accuracy and Velocity. Proof Barrels so far has the been the best barrel I've seen so far .
6mm ARC IMO is the best AR15 CARTRIDGE. The 6arc and 6.5g are true do all be all cartridges for AR15 . 6ARC would be a lot more popular if it wasn't for CV . I'm lucky I bought all my ammo when it was still under 1.50 a round .
Hornady states a 24" Bolt Gun will get 2750 FPS with Match or Black and 2800 FPS with 103g ELDX.
They also state with 18" Proof gas Gun barrel you'll get 2625 FPS . Which is almost on point and not too far off . I'm getting 2600 with my 18" BA .
I'm getting 2400 FPS with my 12" and 2540 FPS with 16" .
The 12" is my do all be all AR15 Pistol . It blows me away every time I shoot it . 600 yards and in for 12" was my primary goal and it hasn't disappointed..
I didnt really shoot for groups until 80 to 100 rounds fires through
I've fallen in love with 6mm ARC
I like the cartridge, and think it’s the best caliber in an AR-15 in terms of accuracy potential and long range ballistics. Since I refit my barrel, my accuracy with the ELDM has improved to .91 inches average for four consecutive three shot groups. If I put each target on top of one another, the 12 shots fall within 1.5 inches. This is a very big improvement over how it was shooting before, and no noticeable change or strange flyers after the barrel heats. I still am considering replacing the barrel, I’d like a 21 inch HB fluted Odin, but it’s not much of a priority since I was able to get the gun to shoot as I had hoped it should. I’m traveling for work now, and just so happened to stop at the closest gun shop and what do you know, they had 6ARC ammo, Hornady black, for 28 bucks a box. Unfortunately, only two boxes, but scooped them up. Current prices that the online scalpers are selling for right now is $2.42 a round cheapest.
If I get the Odin barrel, it’s going to be to test a theory I have to reduce or practically eliminate harmonic vibrations. I don’t want to give away too much, or I may find it as a product for sale (which wouldn’t be the first time). Good luck, and good shooting.
Feel the exact same way about my 12.5 grendel.
Going for the "proof" in the pudding this time...16"
I guess I’ve missed the twist rate of your barrel.
It’s 1:7.5
6mm ARC is not same as necked down 6.5 Grendel. I believe the case shoulder geometry differs also.
Yes, the shoulder is bumped back slightly. I was not trying to get that technical.
Order a bolt action upper from Uintah Precision. Fits right on your lower, Problem solved.
I was able to improve the accuracy with shims, and a re-torque, but thanks for the suggestion.
How do you like the scope position? Seems to be pretty far back. The ammo is definitely way too expensive right now. A ton of the stores are selling the ammo on auction sites instead of offering it to their customers. That way they can get more money, while not being seen to price gouge.
I set the scope position to allow for adjustment in and out of the stock to have the proper eye relief. I want to be able to shorten the stock slightly so that my son can shoot it from time to time.