Proof research 6mm arc feed ramps

[Bigwilly556]

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.

 

[Ledzep]

The wider ramp gives a less aggressive feed cycle. I don't think you'll get a "jamming dud" from either.

 

[AleksanderSuave]

check the gas port size, that was a known change due to some undersized ones that went out.

 

[MSTN]

Proof "big gulp" feed ramps for the win!

 

[Tex68w]

Ooooo, me likey the big gulp ramps, I wish mine had those. That said, I haven't had any FTF issues with the more standard feed ramps in a few hundred rounds.

 

[MaximusDecimusMeidius]

Tagging in. I’ve got a 14.5” proof 6arc on order

 

[Bigwilly556]

Ooooo, me likey the big gulp ramps, I wish mine had those. That said, I haven't had any FTF issues with the more standard feed ramps in a few hundred rounds.

That makes me feel better. Looks like I'm taking the "big gulp". Hopefully my buddies runs good.

 

[45-90]

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.

 

[Blaster7Romeo]

any update if they changed the gas port size ?

 

[45-90]

I almost always open up gas ports on every AR barrel.

 

[Bigwilly556]

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.

 

[Tex68w]

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.

 

[AleksanderSuave]

any update if they changed the gas port size ?

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.

 

[bfoosh006]

I almost always open up gas ports on every AR barrel.

If you please, what was the original GP size , and you opened it up to ?
Also, what gas system length, and barrel length ?

 

[Bigwilly556]

any update if they changed the gas port size ?

Just checked both of mine (18") at .0955 with pin gauge. Close enough to the .096 listed on proofs specs. My dealer showed they purchased these in September 2021.

 

[Tex68w]

.096" is what's supposed to be on the 16" and 18" barrel. Mine gauged at that prior to shipping it off to D. Wilson.

 

[45-90]

If you please, what was the original GP size , and you opened it up to ?
Also, what gas system length, and barrel length ?

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...

 

[bfoosh006]

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...

Thank you.