Proof research 6mm arc feed ramps

Bigwilly556

Bigwilly556

Private
Minuteman
Dec 17, 2021
25
44
Michigan
#1
I just purchased two proof research 18 inch steel 6 arc barrels for a steal that had been sitting at my dealer for some time. Same part number but appears to be a different date code? One has much wider feed ramps than the other. Anyone know if there was an update to widen or narrow the feed ramps because of feeding issues? Proof advised a possible different barrel extension manufacturer? I'll be gifting one and to a friend and I don't want one of us to have jamming dud.
Compress_20240708_170850_0601.jpg
Compress_20240708_170841_1328.jpg
 
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#8
I have 2 6 ARC Proof barrels, I did polish the feed ramps before installing the barrels as usual....so my feed ramps are narrower than the wide ones and different than the narrower ones.
I do not have any feeding issues out of either rifle.
May try some different magazines and also cartridge overall lengths, to help solve the problem.
 
#10
I almost always open up gas ports on every AR barrel.
 

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#11
My buddies grabbing ours from Cera-kote in the next few days. I'll try and have him pin gauge it while he's there. These will both be suppressed with non flow through cans and adjustable gas blocks. If anyone knows how to read the part number/date code I'd be interested to see how old these are.
 
#12
I am using an older non-flow through can (AAC SDN-6) with a non-adjustable gas block (SLR Micro) and a carbine buffer and spring. I have one of the barrels that doesn't have the big gulp feed ramps and I have had ZERO issues with function while using factory loaded Hornady ammo.

*Edit-Very mild recoil and very low gas to face as well, granted I am not shooting strings of rapid fire, it's a long range plinker.
 
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#13
Blaster7Romeo said:
any update if they changed the gas port size ?
Click to expand...
I dont know if it was an update, or if the earlier batches came with a gas port that was not drilled to the correct size.

In either case, their website lists the blueprint with the correct port size and a half-decent micrometer or pin gauge set will confirm if thats accurate or not.
 
#17
bfoosh006 said:
If you please, what was the original GP size , and you opened it up to ?
Also, what gas system length, and barrel length ?
Click to expand...
The gas system is rifle length on an 18" barrel. I use number drills to determine the original size, then move up to the next size, sometimes 2 sizes. Until I get the right functionality. They could start around, .082 but.. .086" to .089" is more likely,
I will go .096" and try, then .098" .0995"
Will usually solve most problems.
But not always.
A gammer rifle, with rifle length gas, on a 16.5" 5.56 and Ti bolt carrier required .122" dia GP to function perfectly at 1085 rounds per minute, with no hammer follow through.
Almost all get drilled out...
 
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#18
45-90 said:
The gas system is rifle length on an 18" barrel. I use number drills to determine the original size, then move up to the next size, sometimes 2 sizes. Until I get the right functionality. They could start around, .082 but.. .086" to .089" is more likely,
I will go .096" and try, then .098" .0995"
Will usually solve most problems.
But not always.
A gammer rifle, with rifle length gas, on a 16.5" 5.56 and Ti bolt carrier required .122" dia GP to function perfectly at 1085 rounds per minute, with no hammer follow through.
Almost all get drilled out...
Click to expand...
Thank you.
 
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