Proof Research 22ARC barrel issues
- Thread starter jpcowboy
- Start date
I'll take a peep at my Craddock Precision RTR 22 ARC Barrel, I've got 60 down it now.
Those Hornady 62gr ELD-VT cook! Im getting close to 3,200fps with a 20" barrel and a Lazarus 6 CAN.
It reminds me of a discussion years ago on gas port erosion, and I wonder if something like a Geissele Phased Array gas port design would help. Ned Christiansen (Michiguns) did something similar to the Phased Array port design around 40 years ago with a .17-.223 wildcat and the expected port erosion issue:
"I was concerned about gas port size relative to bore size, so I drilled two ports of, as I recall, .035. These are drilled at 10:00 and 2:00. Each is capped with a 3-38 set screw; then from where the gas port would normally appear at the outside of the barrel, two holes are drilled perpendicular to the gas ports, so the gas for both ports is channeled into one place that lines up with the hole in the gas block."
"I was concerned about gas port size relative to bore size, so I drilled two ports of, as I recall, .035. These are drilled at 10:00 and 2:00. Each is capped with a 3-38 set screw; then from where the gas port would normally appear at the outside of the barrel, two holes are drilled perpendicular to the gas ports, so the gas for both ports is channeled into one place that lines up with the hole in the gas block."
I had 5 22ARC builds in play and in the break in cycle of about 75-80 rounds per barrel, saw the fall off in accuracy and serious gas port erosion in all 5. To their complete credit, Nick replaced all 5 after their own examination and got them back to me pretty quickly. Happy with Proof customer service and support.
Last I heard from my customer, they’re very happy with accuracy at distance. As they spend a lot of time out in West Texas, haven’t had a chance to scope barrels, but will next opportunity.
Hope Proof does resolve this long term, as other than this issue, very pleased with 6.5GR/CM barrels I have in play personally and with aforementioned customers.
Last I heard from my customer, they’re very happy with accuracy at distance. As they spend a lot of time out in West Texas, haven’t had a chance to scope barrels, but will next opportunity.
Hope Proof does resolve this long term, as other than this issue, very pleased with 6.5GR/CM barrels I have in play personally and with aforementioned customers.
Since most everyone uses the same barrel steels, it would seem to plague the whole 22 ARC AR industry...if true.
The 22 ARC gas volume and high pressure might require manufacturers to move the gas port way down the barrel, like a rifle plus 2.
But ya run out if barrel in a 16" 22 ARC...something that needs to be researched and resolved.
Like a pressed in carbide ring, and or tungsten carbide coating into the gas port to slow erosion, and adjustable gas block.
The 22 ARC gas volume and high pressure might require manufacturers to move the gas port way down the barrel, like a rifle plus 2.
But ya run out if barrel in a 16" 22 ARC...something that needs to be researched and resolved.
Like a pressed in carbide ring, and or tungsten carbide coating into the gas port to slow erosion, and adjustable gas block.
~200-250 rounds on my 18" Proof. Might be something to it. I am not one to chase speed and tend to think the 22 ARC is about as much powder as one should put behind a .224" bullet, especially with 1:7" twist... Be curious to learn more about this.
My Craddock RTR has pretty massive port erosion. I can't take a good photo because I have a Hawkeye bore scope but it's as bad or worse than anything posted above. It did also lose accuracy after about 100rds. Been chasing it for a while. This might explain the issues I've had.
We have not seen this issue yet. I'm not ruling it out entirely but so far it's not been a problem even 1 time that I'm aware of. I think this is because our material is a slightly different composition and runs about 8-9 points harder than the Proof material, plus we're running a Rifle +2 system on all the ARCs. The bigger factor here is probably the R+2 gas system but I can't say for sure at this point.
We don't make 16" barrels but I have tested R+2 16.5 and it does cycle unsuppressed. I didn't feel like subjecting my TBAC to that abuse for something I wasn't planning to make.
The 18 & 20" guns run without problems and don't seem to have this issue that I'm aware of; not in shop test barrels and nobody has reported it to me.
Last edited:
So I checked a bunch of barrels...they all wear at the gas port...how much, seems to depend on the gas pressure at the gas port, its location in the barrel, and barrel material. But they all wear.
The 450 bushmaster is much better than the 6 mm ARC, both 6mm ARC Proof barrels show about the same wear, both 18" but they also have quite a few rds on them.
The shorter the gas tube the higher the pressure, the more wear at this point on the gas ports. Appears to be true for 308 and 6.5 CM.
Between the 6.5 CM and 308 bolt guns that have both have had high pressure hybrid cases fired in them, the stainless steel barreled 308 which has many more rounds has on it has almost no wear, while the CM steel 6.5 CM shows fire cracking, quite a ways down the barrel.
The 6.5 CM is a real barrel eater compared to the 308...about 3 or 4 times more erosion in the 6.5 CM.
The best inspected auto barrel for AR 15 was a 5.56 modified Colt chrome lined H Bar barrel.
Cut to 16.5, fluted, with rifle length gas, lightened bolt carrier.
It can run 1085 rounds per minute in the "gamer gun."
Has fired a thousand rds in one afternoon.
Many thousands of rds through it.
It's been smoking hot, smell steel burni
ng, don't even try to touch the barrel for a half hour hot....go practice with your "nine" while it cools down.
The gas port wear is smooth but not much more wear than a 6 ARC with many hundreds rds on it, instead of many thousands, that was never abused like the 5.6.
The chrome lined Colt barrel still has nice rifling in the lead area with only a few checks in the chrome.
This is the barrel for longevity IMO.
I haven't tried the newer advertised hammer forged machinegun steel, that they supposedly used on the M249 barrels, VS the Colt.
The 450 bushmaster is much better than the 6 mm ARC, both 6mm ARC Proof barrels show about the same wear, both 18" but they also have quite a few rds on them.
The shorter the gas tube the higher the pressure, the more wear at this point on the gas ports. Appears to be true for 308 and 6.5 CM.
Between the 6.5 CM and 308 bolt guns that have both have had high pressure hybrid cases fired in them, the stainless steel barreled 308 which has many more rounds has on it has almost no wear, while the CM steel 6.5 CM shows fire cracking, quite a ways down the barrel.
The 6.5 CM is a real barrel eater compared to the 308...about 3 or 4 times more erosion in the 6.5 CM.
The best inspected auto barrel for AR 15 was a 5.56 modified Colt chrome lined H Bar barrel.
Cut to 16.5, fluted, with rifle length gas, lightened bolt carrier.
It can run 1085 rounds per minute in the "gamer gun."
Has fired a thousand rds in one afternoon.
Many thousands of rds through it.
It's been smoking hot, smell steel burni
ng, don't even try to touch the barrel for a half hour hot....go practice with your "nine" while it cools down.
The gas port wear is smooth but not much more wear than a 6 ARC with many hundreds rds on it, instead of many thousands, that was never abused like the 5.6.
The chrome lined Colt barrel still has nice rifling in the lead area with only a few checks in the chrome.
This is the barrel for longevity IMO.
I haven't tried the newer advertised hammer forged machinegun steel, that they supposedly used on the M249 barrels, VS the Colt.
Gas port erosion has been with us forever. It's just with the advent of more reasonably priced borescopes that that we all get to watch it happen in real time.
Different barrel steels behave in different fashions at the gas port. Gas port erosion really doesn't hurt the barrel's performance as long as the erosion is smooth and gradual. What upsets accuracy is when a little jagged chunk of steel breaks off at the forward edge of the gas port. The bullet doesn't like this. You'll see the trail of copper from that point all the way to the muzzle. Accuracy of course suffers.
Years ago, one renowned AR' barrel maker switched to a super hard SS that would unfortunately do this regularly. After sending so many back, I just had to quit using them.
The only good news I have to share is rough gas port erosion will eventually smooth out after a couple hundred more rounds and the barrel will perform at its earlier capability.
Different barrel steels behave in different fashions at the gas port. Gas port erosion really doesn't hurt the barrel's performance as long as the erosion is smooth and gradual. What upsets accuracy is when a little jagged chunk of steel breaks off at the forward edge of the gas port. The bullet doesn't like this. You'll see the trail of copper from that point all the way to the muzzle. Accuracy of course suffers.
Years ago, one renowned AR' barrel maker switched to a super hard SS that would unfortunately do this regularly. After sending so many back, I just had to quit using them.
The only good news I have to share is rough gas port erosion will eventually smooth out after a couple hundred more rounds and the barrel will perform at its earlier capability.
