Proof Research gas ports undersized?

[Billiam1211]

Curious if anyone running Proof barrels on their gas guns have run into the gas ports being undersized. So far I'm 2/2.

I purchased a Proof stainless steel 24" 6.5 Creedmoor barrel for my large frame AR with a +2 camgas system. Out of the box, accuracy was amazing but it wouldn't lock back on last round. Typically I align my gas block by putting in a borescope and visually confirming that the port is aligned with the gas block. After quite a bit of trouble shooting buffers and such I sent it out to a buddy that's a gunsmith to open up the gas port. Problem solved. Took it out to the range today and it ran flawlessly and maintained the accuracy from before.

In the mean time, I had also purchased a second stainless Proof barrel that was an 18-inch 223 Wylde with a rifle length gas system. Lined up the AGB with borescope and brought it to the range with me today. It would cycle, but wouldn't lock back on last round. Checked again when I got home with the borescope and it lined up. Seems this barrel needs to have the gas port opened up as well.

Anyone else see this issue with Proof AR barrels or is it just me doing something wrong?

Here's a video clip of the borescope footage:

Bill shared 0 photos with you

www.amazon.com

 

[Constructor]

18" rg 223/5.56 should have a .093" port.

Are you running full power loads or working up charges? Don't expect anything to lock back if working up.
Next any gas leaks at the gas block or gas tube can cause problems.

A 2" extended Creed should have a port around .098-.099"

 

[Billiam1211]

18" rg 223/5.56 should have a .093" port.

Are you running full power loads or working up charges? Don't expect anything to lock back if working up.
Next any gas leaks at the gas block or gas tube can cause problems.

A 2" extended Creed should have a port around .098-.099"

I’m running full power loads. I’m running 77gr SMKs at 2,780 fps out of the 18-inch barrel. I'm not seeing any gas leaks. Only reason I'm suspecting the gas port diameter is because it's behaving EXACTLY like my 24-inch 6.5 Creedmoor Proof barrel. On the AR10 I checked the gas block alignment 3 or 4 times, experimented with factory match ammo, reloads, and buffer weights and just couldn't get lock back. Eventually I sent it to a gunsmith and he did confirm the port was a bit undersized (I think he measured it to be .086") so we opened it up.

 

[Billiam1211]

Nope. I have a 24" Proof 6.5CM. paired it with a SLR gas block. Started with it closed. 5 rds and 5 clicks later it was locking back on the mag. Super easy.

Hmm that's how it's supposed to work :|

I guess I ordered 2 barrels both with out of spec gas ports. I would reach out to Proof but their customer service was kinda poor last time I contacted them. They told me to scrap my JP SCS and JP LMOS system because that was likely what was causing the issue... There's no way I'm going to buy a whole new BCG and buffer system just to test. At this point it's just easier to send the barrel off to my buddy and have him fix the port and call it a day and not have to deal with returns. Guess I can chalk it up to the universe telling me to stop tinkering with my ARs haha

 

[wade2big]

Hmm that's how it's supposed to work :|

I guess I ordered 2 barrels both with out of spec gas ports. I would reach out to Proof but their customer service was kinda poor last time I contacted them. They told me to scrap my JP SCS and JP LMOS system because that was likely what was causing the issue... There's no way I'm going to buy a whole new BCG and buffer system just to test. At this point it's just easier to send the barrel off to my buddy and have him fix the port and call it a day and not have to deal with returns. Guess I can chalk it up to the universe telling me to stop tinkering with my ARs haha

You just nailed down your problem. It’s not the barrel.

 

[TheOE800]

My 22” +2 6.5CM Proof gaged ~.086” at the port.

 

[acudaowner]

cause oversized ports aren't always better it's the motion of the ocean not the size of the waves lol so sorry .

 

[Clayman]

I have a proof 6.5cm 22" +1 cam gas, SLR sentry 8 adjustable gas block. I started with it unsuppressed to confirm everything was good to go and do a few groups. Functioned without issue and the gas block was far from all the way open. Since the initial rough zero it's been suppressed and gas was dialed back.

22" proof ss +1 rifle length
JP FMOS enhanced hp bcg
KynSHOT AR10 hydraulic marksman buffer
JP tuned and polished extra power buffer spring

I have an 18" rifle length .223 wylde as well. Same thing, slr block(far from wide open), unsuppressed to check function, roughly sight in and do a few groups. Add suppressor and dial gas back.

18" cf .223 wylde
SLR sentry 7
Jp bcg
Springco green
KynSHOT hydraulic marksman buffer.

 

[Clayman]

Hmm that's how it's supposed to work :|

I guess I ordered 2 barrels both with out of spec gas ports. I would reach out to Proof but their customer service was kinda poor last time I contacted them. They told me to scrap my JP SCS and JP LMOS system because that was likely what was causing the issue... There's no way I'm going to buy a whole new BCG and buffer system just to test. At this point it's just easier to send the barrel off to my buddy and have him fix the port and call it a day and not have to deal with returns. Guess I can chalk it up to the universe telling me to stop tinkering with my ARs haha

Just try a different buffer and spring. It's relatively cheap.

 

[308sako]

Buddy has a 6ARC, simply will not function due to insufficient gas. It's an 18" +1 rifle gas tube. Very disappointed so far factory ammo does not function.

 

[357Max]

Hmm that's how it's supposed to work :|

I guess I ordered 2 barrels both with out of spec gas ports. I would reach out to Proof but their customer service was kinda poor last time I contacted them. They told me to scrap my JP SCS and JP LMOS system because that was likely what was causing the issue... There's no way I'm going to buy a whole new BCG and buffer system just to test. At this point it's just easier to send the barrel off to my buddy and have him fix the port and call it a day and not have to deal with returns. Guess I can chalk it up to the universe telling me to stop tinkering with my ARs haha

The first thing I do with a JP bolt is throw the shitty 1 piece ring in the trash.

If you have the 1 pc ring on the JP bolt, I'd try swapping it out for a 3 pc ring before drilling the port.

 

[bigjake83]

Hmm that's how it's supposed to work :|

I guess I ordered 2 barrels both with out of spec gas ports. I would reach out to Proof but their customer service was kinda poor last time I contacted them. They told me to scrap my JP SCS and JP LMOS system because that was likely what was causing the issue... There's no way I'm going to buy a whole new BCG and buffer system just to test. At this point it's just easier to send the barrel off to my buddy and have him fix the port and call it a day and not have to deal with returns. Guess I can chalk it up to the universe telling me to stop tinkering with my ARs haha

It clearly states on the proof website to run a full mass BCG and H2 buffer system, it's not proofs fault you can't follow basic instructions. Proof literally wrote the book when it comes to proper Gas Port size and location for correct dwell time.

My guess!? You have the Gas Block installed incorrectly or misaligned.

 

[Billiam1211]

It clearly states on the proof website to run a full mass BCG and H2 buffer system, it's not proofs fault you can't follow basic instructions. Proof literally wrote the book when it comes to proper Gas Port size and location for correct dwell time.

My guess!? You have the Gas Block installed incorrectly or misaligned.

Who said I didn’t follow basic instructions? I have a full mass bcg and a h2 buffer on it.. Like I said, I tried everything and was quite thorough when I was troubleshooting. I’ve had a gunsmith confirm that the gas port was undersized on both barrels.

I was curious if anyone else had seen this issue and whether these barrels had a track record, not really looking for advice on how to troubleshoot. Feel free to move along to the next thread

 

[Shifty6BR]

Buddy has a 6ARC, simply will not function due to insufficient gas. It's an 18" +1 rifle gas tube. Very disappointed so far factory ammo does not function.

Same..confirmed gas port was indeed undersized and had it opened up.

 

[Billiam1211]

Same..confirmed gas port was indeed undersized and had it opened up.

I figured there were a few people out there running into this gas port issue.

There wasn’t a whole lot of info on these barrels in general on SH so at least now people might save some time troubleshooting if their Proof barrel won’t cycle.

 

[ut755ln]

Curious if anyone running Proof barrels on their gas guns have run into the gas ports being undersized. So far I'm 2/2.

I purchased a Proof stainless steel 24" 6.5 Creedmoor barrel for my large frame AR with a +2 camgas system. Out of the box, accuracy was amazing but it wouldn't lock back on last round. Typically I align my gas block by putting in a borescope and visually confirming that the port is aligned with the gas block. After quite a bit of trouble shooting buffers and such I sent it out to a buddy that's a gunsmith to open up the gas port. Problem solved. Took it out to the range today and it ran flawlessly and maintained the accuracy from before.

In the mean time, I had also purchased a second stainless Proof barrel that was an 18-inch 223 Wylde with a rifle length gas system. Lined up the AGB with borescope and brought it to the range with me today. It would cycle, but wouldn't lock back on last round. Checked again when I got home with the borescope and it lined up. Seems this barrel needs to have the gas port opened up as well.

Anyone else see this issue with Proof AR barrels or is it just me doing something wrong?

Here's a video clip of the borescope footage:

Bill shared 0 photos with you

www.amazon.com

My ll.5" has had zero problems, not under gassed.

 

[bigjake83]

Who said I didn’t follow basic instructions? I have a full mass bcg and a h2 buffer on it.. Like I said, I tried everything and was quite thorough when I was troubleshooting. I’ve had a gunsmith confirm that the gas port was undersized on both barrels.

I was curious if anyone else had seen this issue and whether these barrels had a track record, not really looking for advice on how to troubleshoot. Feel free to move along to the next thread

Emmure post that I quoted you stated that you were using a LMOS BCG

 

[Billiam1211]

Emmure post that I quoted you stated that you were using a LMOS BCG

Yeah, I also said I did quite a bit of troubleshooting. This included using a full weight carrier, every buffer weight from standard to h3, and 3 different gas blocks. I also had a side convo with Padom here on the hide and he recommended sending it off to open the port. Also, if there’s not enough gas to lock back a light weight carrier it won’t likely lock a full weight carrier. Like I said, I was thorough so when I called Proof and they snubbed me I was kind of annoyed. All that said, the barrel shoots so I’m keeping that prissy bitch on there

 

[Billiam1211]

Am I the only one that just grabs a hand drill and an appropriately sized drill bit when I need a larger gas port?

Or am I not supposed to admit that on the internet?

I was wondering about that… talked to a few guys and they said not to hand drill it because of creating burrs on the inside of the barrel and a reamer would be the way to go. Idk I’m toying with the idea of just drilling it myself with a carbide bit and calling it a day

 

[TheOE800]

So a $20 chucking reamer then?

 

[TonyTheTiger]

Am I the only one that just grabs a hand drill and an appropriately sized drill bit when I need a larger gas port?

Or am I not supposed to admit that on the internet?

You're not the only one.

 

[steve101610]

The first thing I do with a JP bolt is throw the shitty 1 piece ring in the trash.

If you have the 1 pc ring on the JP bolt, I'd try swapping it out for a 3 pc ring before drilling the port.

This is most likely your “undergassed” problem. I had this issue multiple times with JP one piece gas rings. Swapped them out to 3 piece rings and the “undergassed” issue disappeared.

 

[Billiam1211]

This is most likely your “undergassed” problem. I had this issue multiple times with JP one piece gas rings. Swapped them out to 3 piece rings and the “undergassed” issue disappeared.

sorry for the confusion here. The Proof barrel that is currently not cycling is using a full mass Rubber City Armory bcg.

My other Proof barrel in 6.5 was paired with the JP, but this one is now working after drilling out the gas port.

 

[kmdn_crew]

It doesnt sound like they snubbed you. It sounds like you didnt follow some of their advice lol. Get rid of that silent capture spring and go with some of their recommendations.

 

[kmdn_crew]

JP SCS are not incompatible with Proof barrels

They are probably not completely incompatible but a buffer/spring is pretty cheap and could potentially fix the issue. All im saying is if that was their initially recommendation I would give it a try. I have seen it several times where it does seem like general full mass parts just run better.

 

[Billiam1211]

They are probably not completely incompatible but a buffer/spring is pretty cheap and could potentially fix the issue. All im saying is if that was their initially recommendation I would give it a try. I have seen it several times where it does seem like general full mass parts just run better.

So to clarify here - the Proof barrel that is using the JP SCS actually cycles just fine now. This barrel is a 24-inch 6.5 Creedmoor with a +2 gas system. I have a weight kit to take me from standard buffer all the way up to H3 as well as the spring kit for the SCS. I also have a regular buffer / buffer spring. When I was having issues, it didn't work with either. I told Proof this and their recommendation was then to get a full weight carrier. Fortunately, I had one from another large frame AR. Guess what.. that didn't cycle either. I sent it to the smith and he opened up the port to 0.094" and now it cycles like a million bucks. I'm annoyed because I told Proof that I basically tried everything and their response was to just replace all the other parts. Regardless, problem solved when the smith opened up the port.

On my other Proof barrel, which is a 18-inch 223 Wylde / rifle length gas system, I had the same issue except I'm using a full mass rubber city bcg and a regular old buffer spring with an H1, H2, and standard buffer to test. Same issue, wouldn't lock back. 15 minutes ago I actually went in and used a chucked reamer like the guys mentioned and opened up the port. I'll have to go test for reliability soon.

All this said, I learned a thing or 2 about tuning gas guns and how to ream out a gas port. My take away here is that some of these higher end parts will require quite a bit of fitting. I just thought with AR15s it would be more plug and play.

 

[bigjake83]

I love happy endings.

 

[TheOE800]

I love happy endings.

You know a place?

 

[bigjake83]

You know a place?

The Honch in Yokosuka

 

[ReaperDriver]

It clearly states on the proof website to run a full mass BCG and H2 buffer system, it's not proofs fault you can't follow basic instructions. Proof literally wrote the book when it comes to proper Gas Port size and location for correct dwell time.

My guess!? You have the Gas Block installed incorrectly or misaligned.

Sorry, that's BS to attack the poster for not reading instructions. I'm having the exact same issue on an 18"+2 gas system.

I wrote to Proof and they were initially super helpful and responded right away to try a bunch of different things. Obviously they suggested checking the gas block alignment. But this is exactly the email response regarding the spring and weight"

"Thanks for reaching out and I’m sorry to hear about the issues you’re having with your rifle cycling. The main thing I can suggest is making sure you have a standard weight BCG and Carbine spring and carbine buffer (3oz). If you have those three things together the gun should run (we’ve also found that sometimes adjustable gas blocks will leak a little gas and cause things to come up short, so trying a fixed will fix it on occasion.

If the above combination won’t work, it might be necessary to send the barrel back to us to enlarge the gas port size."

So that seems opposite to running the heaviest combo of weights.

I'm going to write to them again and get the gas port opened up as per their offer.

 

[357Max]

Sorry, that's BS to attack the poster for not reading instructions. I'm having the exact same issue on an 18"+2 gas system.

I wrote to Proof and they were initially super helpful and responded right away to try a bunch of different things. Obviously they suggested checking the gas block alignment. But this is exactly the email response regarding the spring and weight"

"Thanks for reaching out and I’m sorry to hear about the issues you’re having with your rifle cycling. The main thing I can suggest is making sure you have a standard weight BCG and Carbine spring and carbine buffer (3oz). If you have those three things together the gun should run (we’ve also found that sometimes adjustable gas blocks will leak a little gas and cause things to come up short, so trying a fixed will fix it on occasion.

If the above combination won’t work, it might be necessary to send the barrel back to us to enlarge the gas port size."

So that seems opposite to running the heaviest combo of weights.

I'm going to write to them again and get the gas port opened up as per their offer.

I've never seen a proof 18" with a +2" gas?? Odin yeah, but not proof.
Sure you don't have 18" +1" camgas?

They're ported efficiently from my limited sample size. Meaning everything has to be within spec and they'll run like a champ as opposed to being over gassed as fuck out of the gate like many.

Pin gauges are your friend especially if your mixing parts like say xyz 6.5 G type 2 bolt in xyz carrier of another brand. It's pretty common for tolerance stacking to add up and knock a fair bit of efficiency from the gas system. In the AR world, things tend to always err on the loose side of spec.

Any combination of the below start to add up and all are common.
Leaking gas block/gas tube in block, worn gas tube, loose gas key bore, leaking gas rings (JP 1 pc), oversize carrier ring bore & or tail bore, or undersized bolt tail.

I try to avoid the above if possible, but if the parts options are limited I've drilled a few. No big deal, just remember it's flow area/gas flow change that matters not hole size. Example: drilling a .086 port to .090 is a 5% increase in drill size, but it is a 10% increase in area. We're talking .004 here. It'd take talent (not the good kind) to make a burr when your removing .002 per side.

 

[ReaperDriver]

I've never seen a proof 18" with a +2" gas?? Odin yeah, but not proof.
Sure you don't have 18" +1" camgas?

They're ported efficiently from my limited sample size. Meaning everything has to be within spec and they'll run like a champ as opposed to being over gassed as fuck out of the gate like many.

Pin gauges are your friend especially if your mixing parts like say xyz 6.5 G type 2 bolt in xyz carrier of another brand. It's pretty common for tolerance stacking to add up and knock a fair bit of efficiency from the gas system. In the AR world, things tend to always err on the loose side of spec.

Any combination of the below start to add up and all are common.
Leaking gas block/gas tube in block, worn gas tube, loose gas key bore, leaking gas rings (JP 1 pc), oversize carrier ring bore & or tail bore, or undersized bolt tail.

I try to avoid the above if possible, but if the parts options are limited I've drilled a few. No big deal, just remember it's flow area/gas flow change that matters not hole size. Example: drilling a .086 port to .090 is a 5% increase in drill size, but it is a 10% increase in area. We're talking .004 here. It'd take talent (not the good kind) to make a burr when your removing .002 per side.

Ah sorry, you are correct. It's an 18" +1 gas system, not +2.

On the other stuff, I'm pretty content that all of the components are top end and brand new. The BCG, type 2 Bolt, adjustable Gas block, buffer and spring are all new JP components. The Gas tube is Proof's that came with the barrel. Mags are specific 6.5G.

I've tried every possible combo of BGC mass (light and heavy) as well as buffer and spring (light and heavy). The only thing I haven't tried is replacing the JP gas rings. On a brand new bolt, is that likely to be enough to cause it to not cycle??? I won't discount it, but it seems such a miniscule thing to cause that consistent a problem.

The problem is this seems to not be a one-off issue. If this many folks are having problems, it points to a manufacturing problem if barrels are not working with common components.

 

[357Max]

Ah sorry, you are correct. It's an 18" +1 gas system, not +2.

On the other stuff, I'm pretty content that all of the components are top end and brand new. The BCG, type 2 Bolt, adjustable Gas block, buffer and spring are all new JP components. The Gas tube is Proof's that came with the barrel. Mags are specific 6.5G.

I've tried every possible combo of BGC mass (light and heavy) as well as buffer and spring (light and heavy). The only thing I haven't tried is replacing the JP gas rings. On a brand new bolt, is that likely to be enough to cause it to not cycle??? I won't discount it, but it seems such a miniscule thing to cause that consistent a problem.

The problem is this seems to not be a one-off issue. If this many folks are having problems, it points to a manufacturing problem if barrels are not working with common components.

Yes the 1 pc ring is enough to cause this on a barrel thats ported efficiently. They may not all be the same, but I’ve had brand new 1 pc rings where the bolt would fall out of the carrier when turned upside down i.e. zero tension. So yeah if your getting + 10 a- 30% blow-by it’s enough on its own. If you understand how a ring seals then the 1 pc ring is a stupid design on its face & when also undersized it’s even worse.

 

[ReaperDriver]

Yes the 1 pc ring is enough to cause this on a barrel thats ported efficiently. They may not all be the same, but I’ve had brand new 1 pc rings where the bolt would fall out of the carrier when turned upside down i.e. zero tension. So yeah if your getting + 10 a- 30% blow-by it’s enough on its own. If you understand how a ring seals then the 1 pc ring is a stupid design on its face & when also undersized it’s even worse.

Ok, I'll try that before I send it back. Thanks!

 

[308sako]

Fyi, it worked!

Standard rings for the win

 

[db2000]

So to clarify here - the Proof barrel that is using the JP SCS actually cycles just fine now. This barrel is a 24-inch 6.5 Creedmoor with a +2 gas system. I have a weight kit to take me from standard buffer all the way up to H3 as well as the spring kit for the SCS. I also have a regular buffer / buffer spring. When I was having issues, it didn't work with either. I told Proof this and their recommendation was then to get a full weight carrier. Fortunately, I had one from another large frame AR. Guess what.. that didn't cycle either. I sent it to the smith and he opened up the port to 0.094" and now it cycles like a million bucks. I'm annoyed because I told Proof that I basically tried everything and their response was to just replace all the other parts. Regardless, problem solved when the smith opened up the port.

On my other Proof barrel, which is a 18-inch 223 Wylde / rifle length gas system, I had the same issue except I'm using a full mass rubber city bcg and a regular old buffer spring with an H1, H2, and standard buffer to test. Same issue, wouldn't lock back. 15 minutes ago I actually went in and used a chucked reamer like the guys mentioned and opened up the port. I'll have to go test for reliability soon.

All this said, I learned a thing or 2 about tuning gas guns and how to ream out a gas port. My take away here is that some of these higher end parts will require quite a bit of fitting. I just thought with AR15s it would be more plug and play.

Did your Smith mention what the port size(s) were before opening them? Just curious. I saw someone mentioned theirs was 0.086.

 

[Billiam1211]

Did your Smith mention what the port size(s) were before opening them? Just curious. I saw someone mentioned theirs was 0.086.

He didn’t mention the initial port size. The port that I opened up myself however was 0.086” and I opened it up to 0.094” with a reamer. I tested it over the weekend and it started cycling perfectly and locking back. Im about 4-5 clicks open in my SLR Sentry 7 AGB.

 

[Billiam1211]

So a $20 chucking reamer then?

ended up doing this. A few days ago I finally managed a range trip to verify. Opened up to .094” with a chucking reamer. Ran 100 rounds without issue and got it cycling and locking back on last round. SLR Sentry 7 is 5 clicks open. Accuracy looks the same so I’ll assume I didn’t ruin the barrel.. at least for now

 

[Bolt Thrower]

Reviving this dormant thread because it helped me. I have a Proof SS 20" 223 barrel with rifle gas and a 0.089" gas port. Shooting unsupressed, the bolt would not hold back on an empty mag and would only cycle 80% of the time with the gas block wide open. Tried various combinations of buffers, springs, BCGs, alternate lower, etc. I spoke to a couple other manufacturers of premium AR barrels and they used larger gas ports ranging from 0.093" to 0.096" for 20" 223 barrels with rifle gas. Eventually I bought a 42 gauge / 0.0935" carbide reamer (https://www.mcmaster.com/30425A456/) and opened up the port myself. The rifle now runs great. No negative effect on precision and the port looks better than it did from the factory (burr removed).

 

[AwkwardlySocial]

Reading above re: lightweight BCGs, is the logic that advises replacing them assuming that the low mass of the carrier means that the bolt tries to unlock too early in the firing cycle and bleeds a lot of momentum overcoming bolt lug friction? And that a full-mass carrier would delay unlock until the appropriate time in the cycle? Or is some other mechanism the culprit for malfunctions associated with lightweight BCGs?

 

[kmdn_crew]

Reading above re: lightweight BCGs, is the logic that advises replacing them assuming that the low mass of the carrier means that the bolt tries to unlock too early in the firing cycle and bleeds a lot of momentum overcoming bolt lug friction? And that a full-mass carrier would delay unlock until the appropriate time in the cycle? Or is some other mechanism the culprit for malfunctions associated with lightweight BCGs?

Full mass basically allows it to not be rushed. It also important to note that a manufacturer and in particular proof have some of their own proprietary gas lengths. These gas lengths as stated on their site are catered to function with said full mass components. Not saying that OP went against this as they do mention they tried other components.

Personal opinion: Low mass bcg's really are just finicky and the benefits don't really outweigh the potential problems they can cause. The thing with AR's essentially being legos is that you get a lot of people that don't have a full understanding and plaster together components and wonder why things dont work. Low mass bcg's can work but they require someone who knows what they are doing and some real fine tuning. Otherwise you are trying to re-tune a system just so it can reliably function with your components..... for alot of people that is just a recipe for problems.

 

[MSTN]

I did a quick count of how many Proof Research AR' barrels in a variety of calibers have been through my door since this thread started. I'm at over 20.

I haven't encountered one single problem like this.

Every one has been assembled with a JP bolt and a full mass bolt carrier by either Young Mfg. or JP. Every one has utilized an SLR adjustable gas block. A variety of recoil systems have been employed - Vltor A5, BCM MK 2, .308 carbine length w/ H2 and H3 buffer, and JP SCS in .223 and .308.

What are we missing?

 

[flogxal]

Several months ago I built a 6 ARC upper, 18" Proof SS. Superlative AdjGB, JP bolt, full-mass carrier. Carbine buffer length, flatwire carbine spring and H1 weight buffer. Quickly tuned within first 10 rds, proceeded to run smoothly. Shot a PRS match about 3 weeks ago with it. Hasn't given me any problems with cycling. But it has not yet seen a suppressor.

I would say I was very impressed with the gas block journal/gas block fit with my chosen combination, a testament to Proof's and SA's good tolerances on their ends of the bargain.

 

[Bolt Thrower]

I did a quick count of how many Proof Research AR' barrels in a variety of calibers have been through my door since this thread started. I'm at over 20.

I haven't encountered one single problem like this.

Every one has been assembled with a JP bolt and a full mass bolt carrier by either Young Mfg. or JP. Every one has utilized an SLR adjustable gas block. A variety of recoil systems have been employed - Vltor A5, BCM MK 2, .308 carbine length w/ H2 and H3 buffer, and JP SCS in .223 and .308.

What are we missing?

Based on my experience, a SS 20" 223 barrel with rifle gas and a 0.089" gas port . It would not lock back on an empty mag unsuppressed with any BCG or buffer system. I tried pretty much every combination before I opened up the gas port and solved the issue. Works fine now and barrel is a tack driver.