6.5cm Precision AR10 Build **Update**

[padom]

Well unfortunately the original thread has been corrupted so all the data, pictures, etc have been lost. To catch everyone up I purchased both a MEGA receiver set and an Aero Precision AR10 receiver set with the intention of testing the Aero Precision set for fit, finish and accuracy since there wasnt much info out there on them back when the original thread was started then selling it off and rebuilding the gun in the MEGA set permanently.

The Aero set was very nice for the money, fit and finish was good and the gun was very accurate. I had a custom 22" Bartlein 6.5cm barrel spun up by Keystone Accuracy that was fluted and had rifle gas. The gun shot consistently 0.5" at 100yds with 123L and 130 ELD-M's. I pulled the barrel and sold it back in December because I wanted the +2 gas for better brass life. I finally received my new 22" Bartlein 6.5cm spun up by Josh over at Patriot Valley Arms with +2 gas and a JP barrel extension.

I put 45 rounds down it that were 43g H4350 and 130 ELD-M in 1xHornady brass that I had loaded up from the last barrel. They shot really good while breaking the barrel in. I then cleaned it and loaded up some 4166 in LC converted brass that hadnt been fireformed yet with 140 Golden Targets. I loaded 36g-39.5g and while it was accurate, those charges were WAY too hot. Loose primer pockets and heavy ejector swipes on all. 37g was 2814 and 39g was 2934 but sub 0.5moa at 100yds groups.

Last night I loaded up some Varget in non-fireformed LC converted brass with 130 ELD-M's in 0.5g increments just to find where the pressure starts. I started lower at 33g and went up to 36g. I normally dont do load development in 0.5g increments but was just trying to find where the loads showed pressure signs. It appears thats right at 36g. This new barrel is very accurate, super smooth and soft shooting with the +2 gas and my can with the gas block tuned to lock back on last round. Im now going to load up 33.8g-35.8g in 0.2g increments to find the center of the node.

Here's my build details since they were lost with my original thread getting corrupted.


22" Bartlein 6.5cm, JP Barrel Extension, +2 Gas
MEGA Maten Receiver Set
Odin Works 15.5" Keymod Handguard
SLR Sentry 9 Clamp AGB
Geissele SD-E
JP LMOS Carrier
JP Enhanced High Pressure Bolt and Firing Pin
JP Centerless Cut Rifle Length Buffer Spring
Rifle Length Buffer
Magpul PRS Stock
ERGO Tactical Deluxe Grip
BCM Charging Handle
Harris Bipod
Rugged 3 Port Timed Muzzle Brake
Rugged Surge 7.62 Suppressor
KAC 20rd Magazines (2.873" Max Coal)


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[padom]

Here's the initial load testing with Varget to find pressure with the new LC converted brass. Loving this brass paired with the +2 gas system. No heavy gauges on the necks and dents in the shoulder like I was getting with my previous barrel and Hornady brass which is the main reason I pulled the barrel and had a new one spun up. Can't wait to fine tune this load and get it out to distance.


LC 7.62 fully prepped, annealed and converted to 6.5cm. These are virgin, not fireformed.
Varget
130 ELD-M
210M
2.81" COAL
0.01" off lands

I did not use the Magnetospeed for this test so I have no idea what velocity is but will test during my next outing.

 

[BallisticSam]

That is great. My go to pet load for my RPR 6.5creedmoor is 35.0gr Varget with 140s. Good to see that the 34.5-35grs of Varget is working for someone else too.

 

[Bigjake83]

Nice build Padom!.
You notice any difference between​ the standard Buffer system Vs the JP SCS??

 

[padom]

Nice build Padom!.
You notice any difference between​ the standard Buffer system Vs the JP SCS??

Thanks bud! She sure is nice.

I dont have a JP SCS... Using a JP Custom Centerless Ground and Polished Rifle Operating Spring and Rifle length buffer. Recoil with this setup and my suppressor shoots like my 5.56!

 

[padom]

Had it back out to the range yesterday doing some more testing with Varget. Very accurate, but slower than I want. 34.5g was 2555. I had tested my previous go to load of 43g H4350 with the same bullet which was 2774 and no pressure signs. Was trying to find a power other than H4350 that gave good speed and accuracy but it looks like Ill be testing H4350.

 

[Forward543]

Im getting 2700 with 140s and 4831sc in a 24" barrel. Its easier to find than h4350

 

[Marine24]

In the process of doing the same thing. Plan to rebarrel a Mega 308 AR
or a Wilson Combat with a barrel from Mark Chanlynn.

Why did you decided on a 22" barrel? Like to understand the logic and apply it.

What glass are you running?


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[atomic41]

That's a very nice rifle. I have a Mega Maten in .308 and plan to build a 6.5C upper for it. I haven't decided what barrel to go with yet.

 

[bobke]

Padom
Yet another first rate build-you set the bar high, which is fully appreciated. I remember you having a pretty good result with AR Comp and 123's in your previous barrel-any thoughts to working around the 37.3 range to compare results?


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[NovaHunter]

Had it back out to the range yesterday doing some more testing with Varget. Very accurate, but slower than I want. 34.5g was 2555. I had tested my previous go to load of 43g H4350 with the same bullet which was 2774 and no pressure signs. Was trying to find a power other than H4350 that gave good speed and accuracy but it looks like Ill be testing H4350.

Have you tried RL 17? I've had good success with it in my bolt gun, accuracy and speed.

It's more temp sensative, but I've been able to control for that in my ballistics app

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[padom]

Yes, next up I plan to test RE17 and AR Comp. Hopefully this week with the new LabRadar.

 

[bobke]

Bump for some load testing results. Like to hear how PVA did with your project, and how the +2 gas is working out.

 

[padom]

I recently did some test with H4350 and 140 ELDM. Its been the best combo to date. Tiny little groups and great velocity. Unfortunetly I only had a partial box left so Im all out. Waiting for my back order to be shipped which hopefully is any day. Going to test the 130ELDM with H4350 next.

 

[elfster1234]

Awesome info!

 

[bobke]

Not dead certain I'm reading this right, but is the 41-41.6 the node, with exception of possible flyer in 41.6, if vertical dispersion is the guideline?

 

[yellowfin]

What's the general thought about the differences/preference between gas blocks from SLR and Odin Works?

 

[8up]

What's the general thought about the differences/preference between gas blocks from SLR and Odin Works?

Both do the exact same thing. I have both in clamp on blocks, I like both of them. One difference I seen was the Odin adjustable gas screw has five detents per revolution, SLR has four per.

 

[Niles Coyote]

I recently did some test with H4350 and 140 ELDM. Its been the best combo to date. Tiny little groups and great velocity. Unfortunetly I only had a partial box left so Im all out. Waiting for my back order to be shipped which hopefully is any day. Going to test the 130ELDM with H4350 next.

41.3 is my most stable node in the 22" jp barrel, with 42.5 another good one but just more narrow. Our velocity match too.