It is odd but I know from putting a factory 16" ACR barrel into an AR that the gas port is too small for it to function in an AR. I had to open the gas port on the barrel before it would cycle correctly. Sounds like Bushmaster made the regulator a little oversized on the U setting and sized the barrel port for what was needed and then made the S setting on the regulator reduce the gas for the increased back pressure of the suppressor.
ACR FTE / Stove pipes
- Thread starter Dusty514
- Start date
No problem bud, glad I could give a bit of my wisdom.
I should actually write a sticky on it so rhat other dlask barrel owners flip it to the S setting.
Im not sure why that is but my theory is that Dlask reversed the U and S positions where U is actually S and S is actually U.
Ok so its not as black and white as people think. A bolt cycling back faster does not mean it extracts stronger, thats just silly.
If the bolt is cycling back too fast, the extractor does not have the necessary time to extract the empty casing, therefore the bolt cycles the cartridge still there, then strips another forward and you have a double feed.
If the bolt is cycling back too slow or too weak it doesnt give enough clearance for the empty to clear, causing it to scrape along the side, not clear, and then the bolt rams forward causing a stovepipe. It can either be a stovepipe alone if the bolt cycles too weak to strip another cartridge, or it can be a stovepipe with a double feed if the bolt just manages to strip a new cartridge forward.
So in actuality you can have too much gas or too little gas and see a failure to extract.
If the bolt is cycling back too fast, the extractor does not have the necessary time to extract the empty casing, therefore the bolt cycles the cartridge still there, then strips another forward and you have a double feed.
If the bolt is cycling back too slow or too weak it doesnt give enough clearance for the empty to clear, causing it to scrape along the side, not clear, and then the bolt rams forward causing a stovepipe. It can either be a stovepipe alone if the bolt cycles too weak to strip another cartridge, or it can be a stovepipe with a double feed if the bolt just manages to strip a new cartridge forward.
So in actuality you can have too much gas or too little gas and see a failure to extract.
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Make a post in the ACR info thread about it for Dlask barrel owners to try if they are having problems.
It's impossible for Dlask to reverse the gas regulator settings. They are only removing the gas system from one barrel and putting it onto another. If they drilled the barrel port to big you would be overgassed on U and what appears to be close to where it should be on S. Overgassing can cause some weird things but this is kinda strange. Did it feel harsh when shooting it on U or did the trigger hit your finger hard when shooting? I noticed with one of my AR's when it was overgassed with an early NEA barrel that it beat up my trigger finger just like my 6.5 inch AR did before I put in a heavier buffer to slow the bolt down.
It's impossible for Dlask to reverse the gas regulator settings. They are only removing the gas system from one barrel and putting it onto another. If they drilled the barrel port to big you would be overgassed on U and what appears to be close to where it should be on S. Overgassing can cause some weird things but this is kinda strange. Did it feel harsh when shooting it on U or did the trigger hit your finger hard when shooting? I noticed with one of my AR's when it was overgassed with an early NEA barrel that it beat up my trigger finger just like my 6.5 inch AR did before I put in a heavier buffer to slow the bolt down.
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canucklehead
CGN Ultra frequent flyer
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- Calgary, AB
This was my thinking as well. They don't change the regulator at all. The only possible answer I guess is that it is overgassed at 'U' and throttled down to 'just right' at 'S' - but I still have no idea how that's possible. Regardless of the port size on the barrel, the restriction that determines the gassing is in the regulator. This isn't like an AR where a bigger gas port flows more gas since there is no adjustable plug. In the ACR the regulator is still the restriction that matters - and Dlask doesn't touch that.
Granted I'm just using logic, which may not apply in this case.
Hmm, well I'll take it regardless.
She's been firing really well but now, not to change the subject, I noticed my firing pin is chipped at the tip? WTF? I thought these titanium pins were pretty solid... Anyone think this could cause slam fire or pierce a primer? I examined some 60 rounds I fired today and compared them to some other rounds from months ago and I don't really see a difference in the striked area. I do know the chip is from today because after I posted this thread and cleaned it, it was perfect.
Am I worrying for nothing?
She's been firing really well but now, not to change the subject, I noticed my firing pin is chipped at the tip? WTF? I thought these titanium pins were pretty solid... Anyone think this could cause slam fire or pierce a primer? I examined some 60 rounds I fired today and compared them to some other rounds from months ago and I don't really see a difference in the striked area. I do know the chip is from today because after I posted this thread and cleaned it, it was perfect.
Am I worrying for nothing?
Sorry for bringing back an old thread, where can I get the BCM enhanced extractor in Canada?
To the previous poster with the chipped firing pin, did you ever have any punctured primer? It only takes a couple of times for the plasma to deform the tip.
To the previous poster with the chipped firing pin, did you ever have any punctured primer? It only takes a couple of times for the plasma to deform the tip.
This was my thinking as well. They don't change the regulator at all. The only possible answer I guess is that it is overgassed at 'U' and throttled down to 'just right' at 'S' - but I still have no idea how that's possible. Regardless of the port size on the barrel, the restriction that determines the gassing is in the regulator. This isn't like an AR where a bigger gas port flows more gas since there is no adjustable plug. In the ACR the regulator is still the restriction that matters - and Dlask doesn't touch that.
Granted I'm just using logic, which may not apply in this case.
The gas system works a lot like the gas system on the Kel-Tec RFB. It's bleeding off excess gas to atmosphere not controlling how much gas comes through the port. The S setting has a larger hole in the regulator and bleeds off more gas which reduces the gas acting on the piston, so since the Dlask barrels have a gas port that is too large the smaller U setting puts too much gas to the piston and the S setting gets rid of the extra and helps it cycle correctly.
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