04-21-2021, 01:48 AM
biodsl,
here's what i tried out and decided to keep. i have a rifle length buffer tube, rifle length buffer spring. rifle length gas system. fixed gas block, however. but i wanted to slow the cycle rate way down for a couple of reasons.
as a kid growing up all i heard about the M16 was that the gas system dumped gas right into the action and it got dirty fast and would fail to function then. i'd never had an AR before so i never got a good look at how the gas system was designed and worked. last year i finally got one.
upon taking it apart and investigating, the expansion chamber in the BCG dumps excess gas out the ejection port through the bolt vents. that shouldn't "dirty up" the action. but what seemed to me a possibility was that if the BCG moved back far enough to expose the end of the gas tube while there was still some, or a lot, of pressure in the barrel, a lot of the powder gasses would indeed be dumped into the action.
since i am not concerned about a fast cycle rate, since i only slow fire the rifle anyway, whether plinking or hunting, it seemed to me that the RLGS would delay the BCG movement vs mid or short length gas system, that a GI BCG would weigh more than these ones that have been lightened for "competition", which i assume was to get a higher cycle rate. also i added a heavibuffer (11oz if i recall correctly) instead of the GI buffer. this adds mass to the reciprocating system and should slow the movement of the BCG. i thought if the BCG gas key never came back past the end of the gas tube until the pressure in the barrel was a lot lower than "normal" then a lot less powder fouling (hopefully none) would get dumped into the action from the end of the gas tube.
this seems to be the case. the action doesn't get very dirty when shot. as a bonus i think delaying the movement of the BCG so that the bolt doesn't start to rotate and extract until the pressure in the bore is even lower than "normal" seems to have an added benefit on lowering the stress on the extractor. i'm running without the rubber donut around the extractor spring. no problems with either extraction or ejection. action does indeed run "slower" but still runs faster than i can get aimed on a target so it's a don't care to me in that regard.
i think there's a lot less stress on the extractor as it rotates on the pivot pin while chambering a round without the donut. and the action runs enough slower that it doesn't seem to need the donut either. so far i've not had any issue with the BCG not coming back far enough to function correctly, whether that is locking the bolt back after the last round or any kind of feeding issue.
another result of the heavibuffer is that the rifle balances a bit further to the rear as compared with the GI rifle buffer installed. not a big deal but it's slightly noticeable. i suspect an adjustable gas block could be used to accomplish the same thing.
i think the more you can delay the movement of the BCG after the round is fired, the lower the stress on the extractor, and the cleaner the action will run. of course you do need enough gas to cycle the action. with just a normal gas block on my rifle, the gas chamber in the BCG is getting fully pressurized as normal, i think, but with the extra mass in the reciprocating assembly, the pressure in the gas tube is much lower by the time the BCG gas key clears the end of the gas tube and the pressure in the bore at the bolt rotation/extraction is a lot lower than "normal" as well. which i think leads to less stress on the extractor and seems to lessen the amount of powder fouling being dumped into the action. my hypothesis anyway.
in use the action doesn't seem to get very "dirty" from powder fouling. some may find the slower cycle rate rather annoying, particularly the competitive shooter kind of folks. but for slower firing, such as plinking or hunting, you won't be bothered by a slightly slower cycle rate, i wouldn't think. it still cycles much faster than i can get the next precisely aimed shot off so i'm not bothered with the slower cycle time.
just commenting in response to your question. i wonder if the folks who do have an adjustable gas block and have it turned down to where the rifle will just function notice a cleaner action and a lower extractor failure rate?
-tdbru
here's what i tried out and decided to keep. i have a rifle length buffer tube, rifle length buffer spring. rifle length gas system. fixed gas block, however. but i wanted to slow the cycle rate way down for a couple of reasons.
as a kid growing up all i heard about the M16 was that the gas system dumped gas right into the action and it got dirty fast and would fail to function then. i'd never had an AR before so i never got a good look at how the gas system was designed and worked. last year i finally got one.
upon taking it apart and investigating, the expansion chamber in the BCG dumps excess gas out the ejection port through the bolt vents. that shouldn't "dirty up" the action. but what seemed to me a possibility was that if the BCG moved back far enough to expose the end of the gas tube while there was still some, or a lot, of pressure in the barrel, a lot of the powder gasses would indeed be dumped into the action.
since i am not concerned about a fast cycle rate, since i only slow fire the rifle anyway, whether plinking or hunting, it seemed to me that the RLGS would delay the BCG movement vs mid or short length gas system, that a GI BCG would weigh more than these ones that have been lightened for "competition", which i assume was to get a higher cycle rate. also i added a heavibuffer (11oz if i recall correctly) instead of the GI buffer. this adds mass to the reciprocating system and should slow the movement of the BCG. i thought if the BCG gas key never came back past the end of the gas tube until the pressure in the barrel was a lot lower than "normal" then a lot less powder fouling (hopefully none) would get dumped into the action from the end of the gas tube.
this seems to be the case. the action doesn't get very dirty when shot. as a bonus i think delaying the movement of the BCG so that the bolt doesn't start to rotate and extract until the pressure in the bore is even lower than "normal" seems to have an added benefit on lowering the stress on the extractor. i'm running without the rubber donut around the extractor spring. no problems with either extraction or ejection. action does indeed run "slower" but still runs faster than i can get aimed on a target so it's a don't care to me in that regard.
i think there's a lot less stress on the extractor as it rotates on the pivot pin while chambering a round without the donut. and the action runs enough slower that it doesn't seem to need the donut either. so far i've not had any issue with the BCG not coming back far enough to function correctly, whether that is locking the bolt back after the last round or any kind of feeding issue.
another result of the heavibuffer is that the rifle balances a bit further to the rear as compared with the GI rifle buffer installed. not a big deal but it's slightly noticeable. i suspect an adjustable gas block could be used to accomplish the same thing.
i think the more you can delay the movement of the BCG after the round is fired, the lower the stress on the extractor, and the cleaner the action will run. of course you do need enough gas to cycle the action. with just a normal gas block on my rifle, the gas chamber in the BCG is getting fully pressurized as normal, i think, but with the extra mass in the reciprocating assembly, the pressure in the gas tube is much lower by the time the BCG gas key clears the end of the gas tube and the pressure in the bore at the bolt rotation/extraction is a lot lower than "normal" as well. which i think leads to less stress on the extractor and seems to lessen the amount of powder fouling being dumped into the action. my hypothesis anyway.
in use the action doesn't seem to get very "dirty" from powder fouling. some may find the slower cycle rate rather annoying, particularly the competitive shooter kind of folks. but for slower firing, such as plinking or hunting, you won't be bothered by a slightly slower cycle rate, i wouldn't think. it still cycles much faster than i can get the next precisely aimed shot off so i'm not bothered with the slower cycle time.
just commenting in response to your question. i wonder if the folks who do have an adjustable gas block and have it turned down to where the rifle will just function notice a cleaner action and a lower extractor failure rate?
-tdbru