Gas port length on a 18.5 308 barrel
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Re: Gas port length on a 18.5 308 barrel
When I asked this question I was told that the longest system that was still reliable was what you wanted. Talk to whomever is doing your barrel, my bet is they tell you rifle length.
When I asked this question I was told that the longest system that was still reliable was what you wanted. Talk to whomever is doing your barrel, my bet is they tell you rifle length.
Re: Gas port length on a 18.5 308 barrel
I know of several DPMS LR308 that started as 24" rifles and have been cut down to 18" and run just fine with the original rifle length gas system and port size.
I prefer rifle length gas systems as they are slightly smoother and have a softer recoil impulse.
I know of several DPMS LR308 that started as 24" rifles and have been cut down to 18" and run just fine with the original rifle length gas system and port size.
I prefer rifle length gas systems as they are slightly smoother and have a softer recoil impulse.
Re: Gas port length on a 18.5 308 barrel
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: smokshwn</div><div class="ubbcode-body">I know of several DPMS LR308 that started as 24" rifles and have been cut down to 18" and run just fine with the original rifle length gas system and port size.
I prefer rifle length gas systems as they are slightly smoother and have a softer recoil impulse. </div></div>
+1 on the above.
I have an AR10T that had the 24" barrel cut down to 18". Works fine.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: smokshwn</div><div class="ubbcode-body">I know of several DPMS LR308 that started as 24" rifles and have been cut down to 18" and run just fine with the original rifle length gas system and port size.
I prefer rifle length gas systems as they are slightly smoother and have a softer recoil impulse. </div></div>
+1 on the above.
I have an AR10T that had the 24" barrel cut down to 18". Works fine.
Re: Gas port length on a 18.5 308 barrel
A rifle length gas system will likely serve you best. Barrels of 18" and longer usually perform well with rifle-length gas systems in the "large platform ARs" while barrels shorter than 18" will generally need a mid-length (or "intermediate" length depending on who makes the barrel) to function reliably.
A rifle length gas system will likely serve you best. Barrels of 18" and longer usually perform well with rifle-length gas systems in the "large platform ARs" while barrels shorter than 18" will generally need a mid-length (or "intermediate" length depending on who makes the barrel) to function reliably.
Re: Gas port length on a 18.5 308 barrel
16" .308's will run rifle gas all day with no issues and do better suppressed than shorter gas system...
An 18.5" bbl should have absolutely no issues running a rifle length gas system, anyone telling you shorter does not have all the data.
16" .308's will run rifle gas all day with no issues and do better suppressed than shorter gas system...
An 18.5" bbl should have absolutely no issues running a rifle length gas system, anyone telling you shorter does not have all the data.
Re: Gas port length on a 18.5 308 barrel
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinB-KAC</div><div class="ubbcode-body">16" .308's will run rifle gas all day with no issues and do better suppressed than shorter gas system...</div></div>
Kevin,
If you can, without "giving away the farm," how are you able to achieve 100% reliability on 16" barrels with rifle-length gas systems shooting unsuppressed (like the SR-25 EMC for example). I assume (probably incorrectly) that timing is everything. Do you have to alter the gas port size along with possibly lightening the carrier, etc., etc.?
Thanks!!
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinB-KAC</div><div class="ubbcode-body">16" .308's will run rifle gas all day with no issues and do better suppressed than shorter gas system...</div></div>
Kevin,
If you can, without "giving away the farm," how are you able to achieve 100% reliability on 16" barrels with rifle-length gas systems shooting unsuppressed (like the SR-25 EMC for example). I assume (probably incorrectly) that timing is everything. Do you have to alter the gas port size along with possibly lightening the carrier, etc., etc.?
Thanks!!
Re: Gas port length on a 18.5 308 barrel
KAC runs a lightened carrier and a heavier buffer. Not sure about gas hole diameter - have not measured one.
IT WORKS.
It also seems to reduce the recoil impulse some compared to my standard DPMS weight bolt carrier and "308" carbine buffer in the UBR.
KAC runs a lightened carrier and a heavier buffer. Not sure about gas hole diameter - have not measured one.
IT WORKS.
It also seems to reduce the recoil impulse some compared to my standard DPMS weight bolt carrier and "308" carbine buffer in the UBR.
Re: Gas port length on a 18.5 308 barrel
9H,
16" rifle length gas systems run well if the gas port is sized properly. I cut the 24" barrel on my DPMS LR-308 to 16" with no issues. I did not need a lighter carrier weight or make any other changes at all to my rifle.
There's no magic dust associated with this simple change. I dont want to get into dewll times, pressure levels at the gas port, and delta-p assosicted with a larger gas port vs a smaller one. I understand how all that works. It seems that the DPMS 308 gas port (at least on my rifle) was sized such that smaller barrel lengths can function with the same port size.
Hope this helps.
9H,
16" rifle length gas systems run well if the gas port is sized properly. I cut the 24" barrel on my DPMS LR-308 to 16" with no issues. I did not need a lighter carrier weight or make any other changes at all to my rifle.
There's no magic dust associated with this simple change. I dont want to get into dewll times, pressure levels at the gas port, and delta-p assosicted with a larger gas port vs a smaller one. I understand how all that works. It seems that the DPMS 308 gas port (at least on my rifle) was sized such that smaller barrel lengths can function with the same port size.
Hope this helps.
Re: Gas port length on a 18.5 308 barrel
I have been cutting them back to 16.5" with a rifle length system for sometime and they run really well.
-Len
I have been cutting them back to 16.5" with a rifle length system for sometime and they run really well.
-Len
Re: Gas port length on a 18.5 308 barrel
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tx_Flyboy</div><div class="ubbcode-body">9H,
16" rifle length gas systems run well if the gas port is sized properly. I cut the 24" barrel on my DPMS LR-308 to 16" with no issues. I did not need a lighter carrier weight or make any other changes at all to my rifle.
There's no magic dust associated with this simple change. I dont want to get into dewll times, pressure levels at the gas port, and delta-p assosicted with a larger gas port vs a smaller one. I understand how all that works. It seems that the DPMS 308 gas port (at least on my rifle) was sized such that smaller barrel lengths can function with the same port size.
Hope this helps. </div></div>
Maybe you should have Kevin hire you as a developer, as clearly they are off base with their design modifications to their system.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tx_Flyboy</div><div class="ubbcode-body">9H,
16" rifle length gas systems run well if the gas port is sized properly. I cut the 24" barrel on my DPMS LR-308 to 16" with no issues. I did not need a lighter carrier weight or make any other changes at all to my rifle.
There's no magic dust associated with this simple change. I dont want to get into dewll times, pressure levels at the gas port, and delta-p assosicted with a larger gas port vs a smaller one. I understand how all that works. It seems that the DPMS 308 gas port (at least on my rifle) was sized such that smaller barrel lengths can function with the same port size.
Hope this helps. </div></div>
Maybe you should have Kevin hire you as a developer, as clearly they are off base with their design modifications to their system.
Re: Gas port length on a 18.5 308 barrel
I run a 18.5" 308 barrel with a rifle length gas system.
Runs great.
The port is 0.100"
I run a 18.5" 308 barrel with a rifle length gas system.
Runs great.
The port is 0.100"
Re: Gas port length on a 18.5 308 barrel
Spoke with two AR builders. The 18" barrel with the rifle gas system needs a bigger gas hole than one with a 20".
.100" is the hole size they both agreed upon for 18" with rifle length system.
Spoke with two AR builders. The 18" barrel with the rifle gas system needs a bigger gas hole than one with a 20".
.100" is the hole size they both agreed upon for 18" with rifle length system.
Re: Gas port length on a 18.5 308 barrel
9H,
Did these builders tell you that you needed carrier weight modifiations etc etc etc per a previous post in this thread?
I'm not trying to start a war, or be sarcastic, but like i previously stated, the simplest way to ensure continued reliability is to make sure that the gas port is properly sized...
9H,
Did these builders tell you that you needed carrier weight modifiations etc etc etc per a previous post in this thread?
I'm not trying to start a war, or be sarcastic, but like i previously stated, the simplest way to ensure continued reliability is to make sure that the gas port is properly sized...
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