Accuracy build help

[tacomHQ]

JP does make a very nice bcg. I have been running their enhanced high pressure bcg with bolt in my ar308 for some time now. Works great and the small diameter firing pin solved my pierced primer problem.

JP makes excellent buffer assemblies, bolt carriers, barrel extensions... guns.
This build uses the first three noted items (Silent Captured Buffer, Standard weight bolt carrier) and runs "like a sewing machine". Very quiet gun on target.
AR10 .260Rem
Aero upper and lower
Vortex Gen ll 3-18
Broughton barrel 1-7.5T
Magpul stock
Accu-Tac bipod
Structured Barrel an custom gas block.

The barrel has way north of 1500rounds on it.
The group shown is 26-30 out of a 30round group at 100yds (5 shot groups, consecutive, 15 to 30sec shot times) . This would have easily continued for the next 20 to 40rds. Front bipod and rear bag.
Temp 58deg, wind 4:30 to 3:00, 6-20+mph. Federal Gold Match 142gr. Final barrel temperature 85deg and fully cool in <15min. Mag fed.
13lbs as shown.

We are building three complete JP's: 6.5CM, 6xc, 6dasher.

 

[tacomHQ]

View attachment 531278View attachment 531279
JP makes excellent buffer assemblies, bolt carriers, barrel extensions... guns.
This build uses the first three noted items (Silent Captured Buffer, Standard weight bolt carrier) and runs "like a sewing machine". Very quiet gun on target.
AR10 .260Rem
Aero upper and lower
Vortex Gen ll 3-18
Broughton barrel 1-7.5T
Magpul stock
Accu-Tac bipod
Structured Barrel an custom gas block.

The barrel has way north of 1500rounds on it.
The group shown is 26-30 out of a 30round group at 100yds (5 shot groups, consecutive, 15 to 30sec shot times) . This would have easily continued for the next 20 to 40rds. Front bipod and rear bag.
Temp 58deg, wind 4:30 to 3:00, 6-20+mph. Federal Gold Match 142gr. Final barrel temperature 85deg and fully cool in <15min. Mag fed.
13lbs as shown.

We are building three complete JP's: 6.5CM, 6xc, 6dasher.

As a note: we have been challenged (Thoughts on Structured Barrels) for a "data" and extended groups. We are starting at 30rd groups. Our 6xc was shown at 40rds (shown) , 300Norma x30rds (shown), etc.... We expect to take those values into the 50's to 100 values before drift shows up. This gun will run multiple bullet weights on the same 100yd zero.

 

[Lee7588]

I will first say I didn't read all of the post in this thread. I have a tool from Brownells that somewhat trues up the face where the barrel mounts the upper. I use 600 grit lapping compound and a hand drill. My groups have tightened up substantially after doing this.

AR-15/M16 UPPER RECEIVER LAPPING TOOL | Brownells

Cold-rolled steel lapping tool chucks into a 3/8' hand drill to easily “square” the upper receiver face on your AR-15. Helps ensure precise mating of barrel and receiver for added accuracy. Coat face of receiver with aluminum-oxide lapping compoun...

www.brownells.com

 

[C-130 Dude]

As a note: we have been challenged (Thoughts on Structured Barrels) for a "data" and extended groups. We are starting at 30rd groups. Our 6xc was shown at 40rds (shown) View attachment 531446View attachment 531449, 300Norma x30rds (shown), etc.... We expect to take those values into the 50's to 100 values before drift shows up. This gun will run multiple bullet weights on the same 100yd zero.

AR308 can be accurate as some of us know. Sometimes it takes a while to get them tuned. And sometimes with a bit of trial and error. Below is my Ar308:
Aero upper
JP handguard
Criterion 20" barrel
JP enhanced high pressure bcg w/bolt and small dia firing pin
Radian charging handle
Magpul enhanced stock extention
Ar15 h4 buffer
Sprinco orange spring
Superlative adj gas block
DPMS lower gen 1
Timney 4 lb AR trigger
American Defense scope mount
Vortex Strike Eagle 5x25x56 moa

Sierra 168 tmk
IMR4064 43.2 grs
LC 15 brass (bought new, once fired by me)
CCI 34 primers

Targets were from 2022 and 2023. 30 shots each target. 100 yards. Magazine fed.

 

[happyshootin]

View attachment 531278View attachment 531279
JP makes excellent buffer assemblies, bolt carriers, barrel extensions... guns.
This build uses the first three noted items (Silent Captured Buffer, Standard weight bolt carrier) and runs "like a sewing machine". Very quiet gun on target.
AR10 .260Rem
Aero upper and lower
Vortex Gen ll 3-18
Broughton barrel 1-7.5T
Magpul stock
Accu-Tac bipod
Structured Barrel an custom gas block.

The barrel has way north of 1500rounds on it.
The group shown is 26-30 out of a 30round group at 100yds (5 shot groups, consecutive, 15 to 30sec shot times) . This would have easily continued for the next 20 to 40rds. Front bipod and rear bag.
Temp 58deg, wind 4:30 to 3:00, 6-20+mph. Federal Gold Match 142gr. Final barrel temperature 85deg and fully cool in <15min. Mag fed.
13lbs as shown.

We are building three complete JP's: 6.5CM, 6xc, 6dasher.

Can you tell me more about the oversized custom gas block? I want to do a 26" structured barrel on an LMT gasser.

 

[Jamie]

I can tell you how I built my 6 ARC.....
I used a thermal fit upper from JP Enterprise and a Proof Research barrel, JP BCG, and JP Silent Capture Spring.. First three shots were the first of the day, it includes the dreaded "cold bore " shot. The other is the next 5 shot I shot.

My other ones, 5.56 and 223 Wylde rifles were built on Aero receivers. They had the face of the upper lapped with a simple hand lapping tool, I ordered different thicknesses of stainless steel shim stock to remove play between barrel and upper, and used a White Oak barrel for the 223 Wylde and a lightweight FN barrel on the 5.56.

 

[bamban]

Here's what a fully prepped AR and properly chambered Bartlein can do. It enabled a shooter, a 20 yo young Texan, to perform to her potential. 80 shot match at Camp Perry she took the top honors in one of the matches among 500+ competitors. That included all the military shooters and civilians from all over the country.

By service rifle rules. 20 inch barrel, no adjustable gas block, 4.5x power max, sling in sitting and prone. 200, 300, and 600 yards.

 

[ntsqd]

I can tell you how I built my 6 ARC.....
I used a thermal fit upper from JP Enterprise and a Proof Research barrel, JP BCG, and JP Silent Capture Spring.. First three shots were the first of the day, it includes the dreaded "cold bore " shot. The other is the next 5 shot I shot.

My other ones, 5.56 and 223 Wylde rifles were built on Aero receivers. They had the face of the upper lapped with a simple hand lapping tool, I ordered different thicknesses of stainless steel shim stock to remove play between barrel and upper, and used a White Oak barrel for the 223 Wylde and a lightweight FN barrel on the 5.56.

I'm not comprehending what you're shimming. Barrel diametrical fit to the upper, or barrel insertion depth?

bamban, that is truly remarkable shooting!

 

[bamban]

I'm not comprehending what you're shimming. Barrel diametrical fit to the upper, or barrel insertion depth?

bamban, that is truly remarkable shooting!

Not the poster. Some barrel extensions (BE) OD to upper ID fit is so sloppy, some people wrap shims around the BE to tighten the fit. Others have some form of locktite to lock the system. These days the heat-to-fit uppers are more common. The best buys are the Bravo blems. They were under $50 before. No need to spend more $$ for those high dollar ones.

Our kids shoot upwards 5K rounds per year with cost effective components with no issues.

For our builds we still use the left over 0.920 long BE with 13/16x20 tpi finished at 1.00x OD instead of the M16 with 13/16x16 at 0.620. I've seen them as low as 0.98 OD.

On the upper face, I do this on the uppers to ensure the face is square with the upper centerline. Some uppers needs as much as 0.008 to clean up, others none. The Bravos have been fairly square.

 

[Charles Duke]

JP will get you there. I took an inexpensive lower (80%) and added JP trigger kit and pins. An Aero upper with all JP- BCG, silent capture, adjustable gas, 20" cryo barrel with brake. Added a VX6 Lupie. With 48 gr Varget pushing 150 Nosler BTs she is 1/2 MOA and runs smooth and steady. Now my go to target and hunting machine.

 

[Jamie]

I'm not comprehending what you're shimming. Barrel diametrical fit to the upper, or barrel insertion depth?

bamban, that is truly remarkable shooting!

Yes, basically taking as much diametrical slop out as possible between the upper and barrel extension.