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Rifles, Reloading, Optics, Equipment
AR15/10 Rifles
Dmr/sdmr build and testing report.
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<blockquote data-quote="pondskipper" data-source="post: 1313025" data-attributes="member: 26430"><p>I think I read the same thing somewhere at one point or another but what I found out was that running an 18" barrel on a rifle length gas system, and shooting very heavy for caliber bullets that it was getting too much gas initially and chewing up cases really bad and ejection was never consistent even though the original BCG and the one I replaced it with were both full auto profile and weighed the same. The reason for this was mainly due to the fact that both 18" barrels had intentionally oversized gas ports. The reason for this was because with 18" barrels with rifle length gas systems have an obviously shorter dwell time from when the bullet passes the gas port to the time it exits the barrel and the pressure drops, they compensate for this shorter length of time by oversizing the hole to let more gas through. I believe this may only be a problem in 18" barrels with rifle length gas systems and wouldn't be an issue with 20" barrels with rifle length gas systems as the gas port isn't oversized in them and they get a much longer dwell time. When I installed the new barrel and adjustable gas block I intentionally left the gas block wide open to see if it still wiped case faces and crushed case necks when it ejected spent cases and it did. Once barrel break in was done I immediately started working on getting the gas block adjusted and once it was finished it threw cases into a 12" diameter circle at about the 4-5 o'clock position and the cases came out basically unharmed, just minor scratches from the rough finish from the original BCG but even those are now gone thanks to the slick finish on the new BCG. To say that everything works in harmony now is an understatement but I've also invested a pile in it to make it what it is and once my tax stamp finally comes back I can't wait to see what it's like with a suppressor on it!</p></blockquote><p></p>
[QUOTE="pondskipper, post: 1313025, member: 26430"] I think I read the same thing somewhere at one point or another but what I found out was that running an 18" barrel on a rifle length gas system, and shooting very heavy for caliber bullets that it was getting too much gas initially and chewing up cases really bad and ejection was never consistent even though the original BCG and the one I replaced it with were both full auto profile and weighed the same. The reason for this was mainly due to the fact that both 18" barrels had intentionally oversized gas ports. The reason for this was because with 18" barrels with rifle length gas systems have an obviously shorter dwell time from when the bullet passes the gas port to the time it exits the barrel and the pressure drops, they compensate for this shorter length of time by oversizing the hole to let more gas through. I believe this may only be a problem in 18" barrels with rifle length gas systems and wouldn't be an issue with 20" barrels with rifle length gas systems as the gas port isn't oversized in them and they get a much longer dwell time. When I installed the new barrel and adjustable gas block I intentionally left the gas block wide open to see if it still wiped case faces and crushed case necks when it ejected spent cases and it did. Once barrel break in was done I immediately started working on getting the gas block adjusted and once it was finished it threw cases into a 12" diameter circle at about the 4-5 o'clock position and the cases came out basically unharmed, just minor scratches from the rough finish from the original BCG but even those are now gone thanks to the slick finish on the new BCG. To say that everything works in harmony now is an understatement but I've also invested a pile in it to make it what it is and once my tax stamp finally comes back I can't wait to see what it's like with a suppressor on it! [/QUOTE]
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Rifles, Reloading, Optics, Equipment
AR15/10 Rifles
Dmr/sdmr build and testing report.
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