Effect of Delayed Unlocking

[SonoranPrecision]

I know this will be a little long winded, but the details might be important on this one.

So I’ve gone down this rabbit hole before, without specifically knowing it. At the time primarily focused on the negative effects of an extremely overpassed system. At the time I was seeing abnormally large groups after adding a suppressor, which was resolved by reducing the gas via a BRT gas tube. It worked quite well, and resulted in the rifle going back to shooting as well as it did prior to adding the can. That said, I would still get random fliers (true fliers, on a 30 shot group, 28rds into 1.2”, the 2 would fly wide and increase the es to 2”) which I chalked up to me just sucking, or getting sloppy.

Fast forward, I built a new upper specifically to help reduce receiver flex/positional poi shift (which was done reasonably successfully with an Aero Enhanced upper and rail). This meant a whole new upper, and allowed to be built with an adjustable gas block this time. Long story short, new upper shoots great, gas is tuned perfectly, still getting random fliers as discussed above, so same conclusion, I must still be doing something weird to cause the fliers.

Then a buddy of mine who works in a local gunshop hits me up and is telling me about this new BCG they have from VKTR (turns out it’s exactly the same as the Leitner Wise bgc) and that I should try it out. After looking into it, their claim to fame is an altered/delayed cam path, that is supposed to unlock the bolt/extract the case 10-15% later than a standard BCG, thus keeping full pressure in the barrel longer, and extracting at lower pressures, which should reduce gas to the face running suppressed. It’s also hard chromed, and a couple other minor advantages, so I figured sure, why not. Worst case it does nothing, and I could use another BCG anyway.

Turns out, it definitely does something. The rifle went from locking back on empty to not locking back. And most interestingly to me, the fliers seem to have disappeared. It was just one group, but it’s August in AZ, so laying on the ground to shoot a group is not comfortable this time of year, and it was a 20rd group in about 2 minutes, so the rifle got quite hot. All that to say, if there were ever conditions that would justify having some fliers it was that.

Obviously I need to do some more testing, but has anyone observed anything similar? Maybe not with the Leitner Wise/VKTR cam path, but I know LMT and Surefire do something similar with a delayed cam path. Does it even make sense that delayed unlocking would have that much of an effect?

 

[carbonbased]

I don’t know the answer to your question, but the Griffin Enhanced Gas Pocket BCG has some delayed unlocking feature too.

From the product page:

“Increased Cam Pin Travel Length for delayed bolt unlock”​

https://griffinarmament.com/shop/griffin-enhanced-gas-pocket-ar-15-bcg/

I can say that that BCG is definitely quieter than a stocker. I bought the whole kit sans the buffer stuff. Gun feels smoother too, but that might be in my head.

Listen to this, much of it is over my head as I’m not an AR-master.

 

[Earnhardt]

Does anyone make this type of BCG for an AR10, or LR308?

 

[alamo5000]

Does anyone make this type of BCG for an AR10, or LR308?

Which BCG are you referring to?

 

[alamo5000]

I know this will be a little long winded, but the details might be important on this one.

So I’ve gone down this rabbit hole before, without specifically knowing it. At the time primarily focused on the negative effects of an extremely overpassed system. At the time I was seeing abnormally large groups after adding a suppressor, which was resolved by reducing the gas via a BRT gas tube. It worked quite well, and resulted in the rifle going back to shooting as well as it did prior to adding the can. That said, I would still get random fliers (true fliers, on a 30 shot group, 28rds into 1.2”, the 2 would fly wide and increase the es to 2”) which I chalked up to me just sucking, or getting sloppy.

Fast forward, I built a new upper specifically to help reduce receiver flex/positional poi shift (which was done reasonably successfully with an Aero Enhanced upper and rail). This meant a whole new upper, and allowed to be built with an adjustable gas block this time. Long story short, new upper shoots great, gas is tuned perfectly, still getting random fliers as discussed above, so same conclusion, I must still be doing something weird to cause the fliers.

Then a buddy of mine who works in a local gunshop hits me up and is telling me about this new BCG they have from VKTR (turns out it’s exactly the same as the Leitner Wise bgc) and that I should try it out. After looking into it, their claim to fame is an altered/delayed cam path, that is supposed to unlock the bolt/extract the case 10-15% later than a standard BCG, thus keeping full pressure in the barrel longer, and extracting at lower pressures, which should reduce gas to the face running suppressed. It’s also hard chromed, and a couple other minor advantages, so I figured sure, why not. Worst case it does nothing, and I could use another BCG anyway.

Turns out, it definitely does something. The rifle went from locking back on empty to not locking back. And most interestingly to me, the fliers seem to have disappeared. It was just one group, but it’s August in AZ, so laying on the ground to shoot a group is not comfortable this time of year, and it was a 20rd group in about 2 minutes, so the rifle got quite hot. All that to say, if there were ever conditions that would justify having some fliers it was that.

Obviously I need to do some more testing, but has anyone observed anything similar? Maybe not with the Leitner Wise/VKTR cam path, but I know LMT and Surefire do something similar with a delayed cam path. Does it even make sense that delayed unlocking would have that much of an effect?

I've never really heard much of anything about the gassing of a rifle causing flyers. There are way too many other factors to consider than just chalking it up to the gassing of the rifle.

One thing you should do though is put each BCG on a scale. Compare the original one to the new one. Odds are they have a weight difference hence the locking back concern.

If you really want to go down the rabbit hole about what an increased unlocking actually does we can absolutely do that, however if you are strictly talking about flyers I think you are chasing a ghost.

 

[SonoranPrecision]

I've never really heard much of anything about the gassing of a rifle causing flyers. There are way too many other factors to consider than just chalking it up to the gassing of the rifle.

One thing you should do though is put each BCG on a scale. Compare the original one to the new one. Odds are they have a weight difference hence the locking back concern.

If you really want to go down the rabbit hole about what an increased unlocking actually does we can absolutely do that, however if you are strictly talking about flyers I think you are chasing a ghost.

What I can say is that I have one rifle that absolutely had the accuracy destroyed by being over gassed. Like doubled the group size, so I know for a fact that unlocking too soon absolutely CAN cause dispersion issues. So it follows that it’s likely not an on/off switch, but rather a sliding scale. But you’re right that causing/curing random fliers MIGHT be a stretch. More likely to see an overall increase in group size, and not fliers. Either way, it seems to me that as long as everything still cycles, delayed unlocking can only benefit the system.

As far as the locking back, it’s not a concern, as adjustable gas took care of it. But I hadn’t thought about the weight of the BCG playing a role. Just put them both on a scale and they weighed exactly the same. Meaning the different cam path is either robbing some energy, the carrier has some other mechanism of ditching excess gas, or the delayed unlocking is lowering residual pressure in the bore during extraction. Or more likely a combination of more than one of those.

 

[Edsel]

Didn’t think they finally translated that idea into an AR bolt carrier, glad they did.

Love the idea of the long, slow, smooth helical cam track.

I imagine that the design enables a slower, higher - torque camming action.

I always wondered if this design would be friendlier to brass.

Long Recoil designs typically have these long cam tracks…

Examples from Singapore are the CIS Ultimax and the SAR-21.

Not entirely sure if the machineguns from Knight’s Armament use a similar cam track in addition to long recoil travel.

Above firearms have James Sullivan’s influence in them.

Then a buddy of mine who works in a local gunshop hits me up and is telling me about this new BCG they have from VKTR (turns out it’s exactly the same as the Leitner Wise bgc) and that I should try it out. After looking into it, their claim to fame is an altered/delayed cam path, that is supposed to unlock the bolt/extract the case 10-15% later than a standard BCG, thus keeping full pressure in the barrel longer, and extracting at lower pressures, which should reduce gas to the face running suppressed. It’s also hard chromed, and a couple other minor advantages, so I figured sure, why not. Worst case it does nothing, and I could use another BCG anyway.

Any chance you could photograph the cam tracks of a regular BCG and that one by VKTR side by side for comparison?

I’m curious about the differences.

 

[Edsel]

This person has similar issues.

 

[SonoranPrecision]

Any chance you could photograph the cam tracks of a regular BCG and that one by VKTR side by side for comparison?

I’m curious about the differences.

So where the cam path of the LMT is elongated with regard to bolt travel forward, the VKTR has an elongated travel in rotation. Standard BCG has 20.7 degrees of bolt rotation, whereas the VKTR has 22.5 degrees. Additionally, looking at them side by side, it appears a standard carrier, as well as the LMT, have straight line movement in the cam path while the bolt is in the fully locked position. However the VKTR flips that around, and puts the straight line travel AFTER the bolt has fully unlocked. I imaging that helps reduce the chance of the cam pin gouging the upper receiver, although I’ve never personally seen a rifle with that issue.

 

[Edsel]

So where the cam path of the LMT is elongated with regard to bolt travel forward, the VKTR has an elongated travel in rotation. Standard BCG has 20.7 degrees of bolt rotation, whereas the VKTR has 22.5 degrees. Additionally, looking at them side by side, it appears a standard carrier, as well as the LMT, have straight line movement in the cam path while the bolt is in the fully locked position. However the VKTR flips that around, and puts the straight line travel AFTER the bolt has fully unlocked. I imaging that helps reduce the chance of the cam pin gouging the upper receiver, although I’ve never personally seen a rifle with that issue.

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Thanks!

I see now.

Instead of “slow unlocking” associated with a long helical path, it’s more of “delayed unlocking.”

Something closer to changing the timing of the “bolt twist.”

 

[Edsel]

I read that you were trying to minimize gas as much as you could, but does your rifle lock back on the last round with just slightly more gas?

 

[SonoranPrecision]

Instead of “slow unlocking” associated with a long helical path, it’s more of “delayed unlocking.”

Something closer to changing the timing of the “bolt twist.”

Definitely a change to the bolt timing. I would almost lean more to a “delayed extraction”. Because the bolt probably is technically unlocked around the same time, but that linear travel in the cam path is after the bolt is unlocked. So the bolt is held in a technically unlocked position for a split second before actually starting to extract the case from the chamber.

I read that you were trying to minimize gas as much as you could, but does your rifle lock back on the last round with just slightly more gas?

Really it only failed to lock back when the can was removed. But yes, a little extra gas and regained full function.

 

[TonyAngel]

I know this will be a little long winded, but the details might be important on this one.

So I’ve gone down this rabbit hole before, without specifically knowing it. At the time primarily focused on the negative effects of an extremely overpassed system. At the time I was seeing abnormally large groups after adding a suppressor, which was resolved by reducing the gas via a BRT gas tube. It worked quite well, and resulted in the rifle going back to shooting as well as it did prior to adding the can. That said, I would still get random fliers (true fliers, on a 30 shot group, 28rds into 1.2”, the 2 would fly wide and increase the es to 2”) which I chalked up to me just sucking, or getting sloppy.

Fast forward, I built a new upper specifically to help reduce receiver flex/positional poi shift (which was done reasonably successfully with an Aero Enhanced upper and rail). This meant a whole new upper, and allowed to be built with an adjustable gas block this time. Long story short, new upper shoots great, gas is tuned perfectly, still getting random fliers as discussed above, so same conclusion, I must still be doing something weird to cause the fliers.

Then a buddy of mine who works in a local gunshop hits me up and is telling me about this new BCG they have from VKTR (turns out it’s exactly the same as the Leitner Wise bgc) and that I should try it out. After looking into it, their claim to fame is an altered/delayed cam path, that is supposed to unlock the bolt/extract the case 10-15% later than a standard BCG, thus keeping full pressure in the barrel longer, and extracting at lower pressures, which should reduce gas to the face running suppressed. It’s also hard chromed, and a couple other minor advantages, so I figured sure, why not. Worst case it does nothing, and I could use another BCG anyway.

Turns out, it definitely does something. The rifle went from locking back on empty to not locking back. And most interestingly to me, the fliers seem to have disappeared. It was just one group, but it’s August in AZ, so laying on the ground to shoot a group is not comfortable this time of year, and it was a 20rd group in about 2 minutes, so the rifle got quite hot. All that to say, if there were ever conditions that would justify having some fliers it was that.

Obviously I need to do some more testing, but has anyone observed anything similar? Maybe not with the Leitner Wise/VKTR cam path, but I know LMT and Surefire do something similar with a delayed cam path. Does it even make sense that delayed unlocking would have that much of an effect?

I dont know, bud. It seems to me that you're chasing a phantom. One or two fliers in a high round count group could be caused by anything, including the rifle reacting more violently. In my experience, gassing has very little to do with accuracy and that which it does affect is due to the rifle shooting more smoothly.

Honestly, I don't see the benefit of a carrier that delays unlocking of the bolt. Well, I suppose it could serve a purpose in rifles that are more than slightly overgassed, but I don't see how its gonna help otherwise. By altering, or increasing, the closed bolt lock time you are requiring additional gas through the tube to return the rifle to a state where it will fire reliably. You're essentially creating a condition similar to having worn out rings.

The only advantage that I can imagine right now is that it might allow you to run less reciprocating mass (a lighter buffer).

 

[flogxal]

Maybe too tree-tops level here, but -- in a semi-auto platform like the AR-15, with so many moving parts in the auto-reload side and the gassing side, and a less-then-TopFuel Dragster set of tolerances in the gassing piston/rings and other systemic gas consistency... isn't a flier in 20+ shots somewhat expected even if we'd like it otherwise?

 

[msgriff]

The issues that people deal with today regarding back pressure and suppressors are the same issues they had when first testing suppressors on an M16A1 back in the 1960's. Here's a link below to an article from 2002 which briefly explains some of the issues and solutions, I think that I have a PDF of the actual report somewhere. The parameter was that the rifle must function in both full and semi-auto, with or without the suppressor. Other than altering the suppressor design, a modified BCG was the only change directly affecting function. They did not alter the cam path, but simply added an extra exhaust port to the carrier. Ultimately, the tests showed too many problems to field a suppressed M16 at that time, other than the limited numbers issued for field testing.

A brief excerpt from the article (note: M4 was the designator for the suppressor, and not the carbine which was later developed):

"Early development at Aberdeen also demonstrated that the M4 generated a number of problems with the M16A1 rifle: (1) increased back pressure; (2) increased cyclic rate; (3) increased rearward bolt velocity, and (4) excessive gas discharge from the ejection port into the shooter’s face. The major problem was the increased back pressure, which actually produced the other problems, such as shearing off the bolt carrier key. HEL solved the bolt velocity and cyclic rate problems by adding an additional gas pressure relief port to the bolt carrier, which enabled reliable functioning of the rifle whether the selector was set to SEMI or AUTO.
The only glitch with this solution was that the rifle would not cycle reliably with the modified bolt carrier unless the suppressor was installed. This meant that a rifle fitted with the modified bolt carrier had to be dedicated for suppressed use only."

Link to article, which is partially corrupted as some images are no longer available:
https://smallarmsreview.com/hel-5-56mm-suppressors-for-the-m16a1/

 

[Edsel]

I think that I have a PDF of the actual report somewhere.

Interested, please post…

 

[JR1200W3]

Delayed cycling has been proven in multiple platforms to have several benefits, no?

MP5. Known for smoother and reduced recoil

CMMG radial blowback AR PCC, reduces direct blowback velocity and ejection port pop.

Is the concept that leaving the bolt head locked until chamber pressure decreases is an advantage debatable?

Or is the debate how much longer the elongated cam path leaves the bolt locked?

Or is the only debate it's contribution to accuracy?

I've seen accuracy change as I've adjusted gas on an ADJ gas block on a particular large frame gas gun. From way over gassed to just under gassed. It was noticable. But I've only tested and seen it in one rifle.

 

[TonyAngel]

Delayed cycling has been proven in multiple platforms to have several benefits, no?

MP5. Known for smoother and reduced recoil

CMMG radial blowback AR PCC, reduces direct blowback velocity and ejection port pop.

Is the concept that leaving the bolt head locked until chamber pressure decreases is an advantage debatable?

Or is the debate how much longer the elongated cam path leaves the bolt locked?

Or is the only debate it's contribution to accuracy?

I've seen accuracy change as I've adjusted gas on an ADJ gas block on a particular large frame gas gun. From way over gassed to just under gassed. It was noticable. But I've only tested and seen it in one rifle.

I don't think there is a question that increasing closed bolt lock time can be beneficial. My question is why do it this way. Unless I'm mistaken, this bolt/Carrier system goes for upwards of $500. On top of that, you're committing yourself to a proprietary BCG, spring and buffer. Why?

The same thing can be accomplished a couple of different ways. Adjustable gas block and/or buffer weight. All this BCG does is cause the system to need more gas to operate properly. So, if you take a rifle that runs perfectly on a standard carbine and spring, what's going to happen when you add this BCG?

 

[JR1200W3]

I don't think there is a question that increasing closed bolt lock time can be beneficial. My question is why do it this way. Unless I'm mistaken, this bolt/Carrier system goes for upwards of $500. On top of that, you're committing yourself to a proprietary BCG, spring and buffer. Why?

The same thing can be accomplished a couple of different ways. Adjustable gas block and/or buffer weight. All this BCG does is cause the system to need more gas to operate properly. So, if you take a rifle that runs perfectly on a standard carbine and spring, what's going to happen when you add this BCG?

Well, because dropping the gas or upping the buffer weight only delays unlocking so much and people are trying to figure out how to delay it longer. It would seem, no? And I don't think you need a proprietary buffer tube, spring and buffer for the LMT BCG do you? Or the BCG in the OP? Or the Surefire OBCG?

I'm interested in this as a way to get a quieter suppressed AR with less gas. I'm not sure that it's a real solution yet. I do agree optimally gassing the rifle should be a shooter's first step before anything else. And I suspect that the benefits of these alternative BCGs are really diminished once the gas is adjusted. I have limited experience with these type of BCGs. I tried a KSPEC on a rifle that was severely over gassed. I tuned the gas port and made it much smoother, less recoil and ejection port gas, and a tad quieter. Then I dropped the K SPEC BCG in. I was pretty disappointed but I suspected all along the difference was going to be super negligible. I think a person would have a hard time telling any difference between the KSPEC and a standard BCG in a well gassed gun. So maybe it's the same situation with these delayed unlocking, elongated cam path BCGs. But maybe it isn't. Having less opportunity for gas and sound to escape the ejection port would be cool. If the Griffin side pocket BCG demonstrated a noticable difference (in an already properly gassed gun)that eliminated a substantial amount of gas and was quieter at the shooters ear, I would commit to a proprietary buffer tube, buffer, and BCG. My only issue would be the cost.

 

[TonyAngel]

Well, because dropping the gas or upping the buffer weight only delays unlocking so much and people are trying to figure out how to delay it longer. It would seem, no? And I don't think you need a proprietary buffer tube, spring and buffer for the LMT BCG do you? Or the BCG in the OP? Or the Surefire OBCG?

I'm interested in this as a way to get a quieter suppressed AR with less gas. I'm not sure that it's a real solution yet. I do agree optimally gassing the rifle should be a shooter's first step before anything else. And I suspect that the benefits of these alternative BCGs are really diminished once the gas is adjusted. I have limited experience with these type of BCGs. I tried a KSPEC on a rifle that was severely over gassed. I tuned the gas port and made it much smoother, less recoil and ejection port gas, and a tad quieter. Then I dropped the K SPEC BCG in. I was pretty disappointed but I suspected all along the difference was going to be super negligible. I think a person would have a hard time telling any difference between the KSPEC and a standard BCG in a well gassed gun. So maybe it's the same situation with these delayed unlocking, elongated cam path BCGs. But maybe it isn't. Having less opportunity for gas and sound to escape the ejection port would be cool. If the Griffin side pocket BCG demonstrated a noticable difference (in an already properly gassed gun)that eliminated a substantial amount of gas and was quieter at the shooters ear, I would commit to a proprietary buffer tube, buffer, and BCG. My only issue would be the cost.

Honestly, I may be mistaken about the proprietary parts with regard to the subject of this post. There are, however, other BCGs that seek to do the same thing, that are comprised of proprietary parts.

I don't quite get what you mean by either the buffer or an adjustable gas block only being able to increase lock time by so much, implying that the BCG can increase lock time beyond what can be done with another method, while still having a running rifle. Either buffer weight or an adjustable gas block can be used to increase lock time to a point where there is no longer sufficient pressure to operate the system.

Still, there is such a thing as too much closed bolt lock time. The longer the bolt stays closed after a round is fired, the lower the pressure available to cycle the action.

Again, taking the example of the properly gassed rifle that runs well on a standard buffer and spring. Now, take that rig and drop in a BCG that increases the closed bolt lock time. What happens? By the time the bolt unlocks, there is likely no longer pressure sufficient to cycle the bolt with its existing mass. So, what do you do? Reduce the reciprocating mass and/or spring rate/tension? I can see this having a negative impact on reliability as the rifle is fired and gets more and more dirty. It will get to a point where the buffer mass and/or spring no longer have enough umph to peel another round off of a fresh magazine.

If you look at it from the opposite side, with a severely overgassed rifle. Say an 11.5 with a .078 or .080 gas port. You're getting stuck cases and the rifle is beating itself to death. In this case, I doubt that the lock time added by this BCG will fix the problem without some help from either a heavier buffer or adjustable gas block. In this case, you could have just omitted the BCG with the use of the other two items.

The only point I'm trying to make is that this BCG being discussed would likely do well with a slightly overgassed system, but the solution isn't worth the expense when you can get the same result with a $200 riflespeed and/or $30 buffer, while getting a lot more flexibility.

Still, what would be interesting to see is if you take, say an 11.5 with a .070 gass port. Perfect. But then you throw something like a Polonium or YHM Fatcat on the end of it for a dedicated suppressed rig. Will this BCG delay the unlocking enough to rein in the added pressure and do something about the gas face. If so, this BCG may be a good option without having to mess with an adjustable gas block.

 

[Edsel]

It makes sense to have a relatively overgassed system with a long, low - pitch cam track in the context of operational reliability.

I would imagine that is what the overall design of the SAR-21 accomplishes.

Think having the same reliable engine geared differently - for track vs. offroading, such as in some American V8 designs.

 

[JR1200W3]

I don't quite get what you mean by either the buffer or an adjustable gas block only being able to increase lock time by so much, implying that the BCG can increase lock time beyond what can be done with another method, while still having a running rifle. Either buffer weight or an adjustable gas block can be used to increase lock time to a point where there is no longer sufficient pressure to operate the system.

Still, there is such a thing as too much closed bolt lock time. The longer the bolt stays closed after a round is fired, the lower the pressure available to cycle the action.

Again, taking the example of the properly gassed rifle that runs well on a standard buffer and spring. Now, take that rig and drop in a BCG that increases the closed bolt lock time. What happens? By the time the bolt unlocks, there is likely no longer pressure sufficient to cycle the bolt with its existing mass. So, what do you do? Reduce the reciprocating mass and/or spring rate/tension? I can see this having a negative impact on reliability as the rifle is fired and gets more and more dirty. It will get to a point where the buffer mass and/or spring no longer have enough umph to peel another round off of a fresh magazine.

If you look at it from the opposite side, with a severely overgassed rifle. Say an 11.5 with a .078 or .080 gas port. You're getting stuck cases and the rifle is beating itself to death. In this case, I doubt that the lock time added by this BCG will fix the problem without some help from either a heavier buffer or adjustable gas block. In this case, you could have just omitted the BCG with the use of the other two items.

The only point I'm trying to make is that this BCG being discussed would likely do well with a slightly overgassed system, but the solution isn't worth the expense when you can get the same result with a $200 riflespeed and/or $30 buffer, while getting a lot more flexibility.

Still, what would be interesting to see is if you take, say an 11.5 with a .070 gass port. Perfect. But then you throw something like a Polonium or YHM Fatcat on the end of it for a dedicated suppressed rig. Will this BCG delay the unlocking enough to rein in the added pressure and do something about the gas face. If so, this BCG may be a good option without having to mess with an adjustable gas block.

I think you're making the assumption that an AR can't experience longer lock time or delay without malfunctioning. This is what these products promise. If we see ourselves as having open minds and welcoming efforts of companies trying to achieve this, I think we should at least predicate the discussion on this capability. If you're right, and it's not possible, then your right. But if you haven't tried and tested them and your just eliminating the concept through assumption then it's just an uninformed opinion. I don't say that to be overly aggressive or confrontational. It's just what it is.

I don't see the value in using this product as an alternative to just properly gassing a rifle. To your original point, why? Just build the rifle better and save money. I think it's value lies in extending the capability of longer lock time and reduced ejection port gas after conventional methods have done their best. To give additional performance that can't be gained by more simple and proper build methods. I guess an example of this would be the comparison of the MP5 vs a direct blowback PCC. No matter how you buffer a DBB PCC, it's not going to equate to a roller delayed mechanism.

 

[Wormydog1724]

I have two Griffin Gas Pocket BCG's (one "enhanced" with the shorter gas key for longer stroke, and one 'milspec').

They both, for me, 100% make a suppressed AR quieter. I don't think they changed my gas/overgas all that much, I'm currently running standard A2 buffers with Tubb FlatWire springs and with the suppressors attached, they're overgassed (or were, more below).

Both rifles, with cans, were overgassed. One is a KAC LPR Mod 2 (proprietary gas block/tube) with an OCM5 can, the other is a Bison Fulcrum (proprietary gas block, intermediate gas tube). The KAC LPR has the 'enhanced' GA GP BCG, the Fulcrum has the 'milspec' GA GP BCG.

Since the milspec GA GP BCG has the standard gas key, I replaced the key with a Rubber City Armory Adjustable Gas Key. The RCA AGK tamed the gas on the Fulcrum barrel by limiting the amount of gas that goes into the GA GP BCG and made a softer, more pleasant rifle to shoot. If I wanted to do the same to the KAC LPR Mod 2, I'd need to get a milspec GA GP BCG and swap the key on it. I don't think I will just yet.

I am running pretty spicy loads with 77gr SMK (also 73gr ELDM), AA2520 with NAS3 cases. I was getting odd fliers with the 73gr ELDM and gave up on them after a couple hundred rounds.

This delayed/gas/flier discussion at the beginning has me wondering, what if I shutoff the gas? Yeah, it'll turn it into a single shot but if the pressure/gas is causing the fliers, removing that might fix it? Or not. Maybe.

Just thinking out loud a bit. Something to try this weekend.

 

[Bluedog82]

LW LABC made this noticeably more controllable.

 

[JR1200W3]

I have two Griffin Gas Pocket BCG's (one "enhanced" with the shorter gas key for longer stroke, and one 'milspec').

They both, for me, 100% make a suppressed AR quieter. I don't think they changed my gas/overgas all that much, I'm currently running standard A2 buffers with Tubb FlatWire springs and with the suppressors attached, they're overgassed (or were, more below).

Both rifles, with cans, were overgassed. One is a KAC LPR Mod 2 (proprietary gas block/tube) with an OCM5 can, the other is a Bison Fulcrum (proprietary gas block, intermediate gas tube). The KAC LPR has the 'enhanced' GA GP BCG, the Fulcrum has the 'milspec' GA GP BCG.

Since the milspec GA GP BCG has the standard gas key, I replaced the key with a Rubber City Armory Adjustable Gas Key. The RCA AGK tamed the gas on the Fulcrum barrel by limiting the amount of gas that goes into the GA GP BCG and made a softer, more pleasant rifle to shoot. If I wanted to do the same to the KAC LPR Mod 2, I'd need to get a milspec GA GP BCG and swap the key on it. I don't think I will just yet.

I am running pretty spicy loads with 77gr SMK (also 73gr ELDM), AA2520 with NAS3 cases. I was getting odd fliers with the 73gr ELDM and gave up on them after a couple hundred rounds.

This delayed/gas/flier discussion at the beginning has me wondering, what if I shutoff the gas? Yeah, it'll turn it into a single shot but if the pressure/gas is causing the fliers, removing that might fix it? Or not. Maybe.

Just thinking out loud a bit. Something to try this weekend.

It would be interesting to see what you find. One thing to consider is first and last round flyers that can be due to BCG tilt and bolt bounce. I think you'd have to eliminate those first because firing single shot/no gas it will eliminate those results and provide a false correlation. While you're at it, you might as well hand feed them too.

 

[flogxal]

Since the milspec GA GP BCG has the standard gas key, I replaced the key with a Rubber City Armory Adjustable Gas Key. The RCA AGK tamed the gas on the Fulcrum barrel by limiting the amount of gas that goes into the GA GP BCG and made a softer, more pleasant rifle to shoot. If I wanted to do the same to the KAC LPR Mod 2, I'd need to get a milspec GA GP BCG and swap the key on it. I don't think I will just yet.

I have an RCA adjustable gas key that I haven't tried yet. One thing I wonder -- since it chokes gas at the carrier, rather than at the gas block further upstream toward the muzzle, do you notice any difference at the port? Or is the suppressor adding so much at the port it's not noticeable?

 

[Wormydog1724]

I am 100% not going to do that because I use these for a gas gun competitions and there’s absolutely no point in chasing it that far.

 

[Wormydog1724]

I have an RCA adjustable gas key that I haven't tried yet. One thing I wonder -- since it chokes gas at the carrier, rather than at the gas block further upstream toward the muzzle, do you notice any difference at the port? Or is the suppressor adding so much at the port it's not noticeable?

The ejection port? I dunno, my ears and electronic hearing protection likely isn’t sensitive enough to tell a difference. The GA GP BCG already directs it all back into the upper so any extra port noise from the gas tube/RCA AGK is probably moot.

 

[TonyAngel]

I think you're making the assumption that an AR can't experience longer lock time or delay without malfunctioning. This is what these products promise. If we see ourselves as having open minds and welcoming efforts of companies trying to achieve this, I think we should at least predicate the discussion on this capability. If you're right, and it's not possible, then your right. But if you haven't tried and tested them and your just eliminating the concept through assumption then it's just an uninformed opinion. I don't say that to be overly aggressive or confrontational. It's just what it is.

I don't see the value in using this product as an alternative to just properly gassing a rifle. To your original point, why? Just build the rifle better and save money. I think it's value lies in extending the capability of longer lock time and reduced ejection port gas after conventional methods have done their best. To give additional performance that can't be gained by more simple and proper build methods. I guess an example of this would be the comparison of the MP5 vs a direct blowback PCC. No matter how you buffer a DBB PCC, it's not going to equate to a roller delayed mechanism.

Wow. You do realize that my entire post dealt with adjusting the closed bolt lock time on an AR15, right? What do you think it is that you are doing when you add mass to the BCG/buffer or turn the gas down? You are increasing the closed bolt lock time. Your response leads me to believe that you think adding buffer mass or adjusting the gas is all about bolt velocity. Bolt velocity itself could easily be controlled with the spring and it sounds like you are conflating the two.

All this BCG, that we are talking about here, aside from the other attributes, does is effectively make the system think you're running a buffer one or two steps heavier and/or reduced gas. Either extends closed bolt lock time to allow the bolt to unlock when pressure has subsided, consequently slowing bolt velocity.

I have two Griffin Gas Pocket BCG's (one "enhanced" with the shorter gas key for longer stroke, and one 'milspec').

They both, for me, 100% make a suppressed AR quieter. I don't think they changed my gas/overgas all that much, I'm currently running standard A2 buffers with Tubb FlatWire springs and with the suppressors attached, they're overgassed (or were, more below).

Both rifles, with cans, were overgassed. One is a KAC LPR Mod 2 (proprietary gas block/tube) with an OCM5 can, the other is a Bison Fulcrum (proprietary gas block, intermediate gas tube). The KAC LPR has the 'enhanced' GA GP BCG, the Fulcrum has the 'milspec' GA GP BCG.

Since the milspec GA GP BCG has the standard gas key, I replaced the key with a Rubber City Armory Adjustable Gas Key. The RCA AGK tamed the gas on the Fulcrum barrel by limiting the amount of gas that goes into the GA GP BCG and made a softer, more pleasant rifle to shoot. If I wanted to do the same to the KAC LPR Mod 2, I'd need to get a milspec GA GP BCG and swap the key on it. I don't think I will just yet.

I am running pretty spicy loads with 77gr SMK (also 73gr ELDM), AA2520 with NAS3 cases. I was getting odd fliers with the 73gr ELDM and gave up on them after a couple hundred rounds.

This delayed/gas/flier discussion at the beginning has me wondering, what if I shutoff the gas? Yeah, it'll turn it into a single shot but if the pressure/gas is causing the fliers, removing that might fix it? Or not. Maybe.

Just thinking out loud a bit. Something to try this weekend.

I run riflespeed gas blocks on my rigs. Although each is a bit different when it comes to tuning, you can tailor the gas adjustment range by changing the plunger. On my longer distance and 300BO rigs, I use plunger sizes that allow me to completely turn the gas off. Its a nice feature to have on tap when target shooting or you want things as quiet and gas free as possible.

On my goto rig, I have it setup so that setting 1 is my base for good cycling when suppressed on a clean rifle.

Anyway, what you're talking about doing isn't in the least bit unusual.

 

[JR1200W3]

Wow. You do realize that my entire post dealt with adjusting the closed bolt lock time on an AR15, right? What do you think it is that you are doing when you add mass to the BCG/buffer or turn the gas down? You are increasing the closed bolt lock time. Your response leads me to believe that you think adding buffer mass or adjusting the gas is all about bolt velocity. Bolt velocity itself could easily be controlled with the spring and it sounds like you are conflating the two.

All this BCG, that we are talking about here, aside from the other attributes, does is effectively make the system think you're running a buffer one or two steps heavier and/or reduced gas. Either extends closed bolt lock time to allow the bolt to unlock when pressure has subsided, consequently slowing bolt velocity.

You're taking what I said out of context and not thinking it through. The context of my statement you're responding to is... using the elongated cam path BCG. As in, "I think you're making the assumption that an AR can't experience longer lock time or delay (sic: using and elongated cam path BCG) without malfunctioning". That's not the same as "I think you're making the assumption that an AR can't experience longer lock time or delay (with any BCG at all) without malfunctioning" which is how you responded.

You keep trying to discuss this using an assumption that upping buffer weight is 1:1 equal to an elongated cam path BCG. But you've never compared those to prove it. I haven't either but I'm willing to entertain the possibility there's additional gains to an elongated cam path BCG over just using a heavier buffer, until it's proven otherwise. You aren't. That's why I talk about keeping an open mind unless you've tried it yourself. Otherwise it's an uninformed opinion.

You and I first clashed because I disagreed with your statements about swapping buffers up to solve over gassing issues. You've always spoken like adjusting buffer weights is 1:1 equivocal to solving gas issues at the gas port. The two are not the same. For one, you're not eliminating as much gas at the ejection port by upping buffer weight as you will by reducing gas coming out of the gas tube to achieve the same function of cycling. And for two, adjusting gas port size by the usual increments of .003 results in a more drastic effect to cycling than does jumping one buffer weight size, H1 to H2. If a person is dealing with enough under gas or over gas, they could run through all the available buffer weights before solving the issue.

It's obvious, your solution to everything is swapping buffers and you really can't see any other possibilities.

 

[DeadFox]

I thought I remember seeing a study on unlock timing affects from heavier buffers and it wasn’t significant. I’ll see if I can find it. Makes sense as the buffer weight isn’t really part of the carrier mass and the weights are basically loose in the buffer.

As the tub “CWS” is discontinued, this is interesting to me

 

[bfoosh006]

I wish Tubbs still made the CWS. It was a simple way to "experiment" with the mass of the recoil system.