How important is the +2 gas system on a 6.5 Creedmoor large frame AR? What will the downside be of using a rifle length gas system?
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It would not be as preferable as a 22" with +2, and not as bad as a 22" with Rifle.
the main key is the adjustable gas block more than anything.. i have a custom made from the ground up mega 6.5 AR with a 22" barrel with an extra 2" gas and IMO it makes for a super smooth shooting AR and is my crown jewel in my collection... with the custom brake = shoots damn near like a .223... i was in the middle of making a complete series on my MEGA 6.5 creedmoor when i found out about my whole cancer ordeal..... which i hope to pick up soon late spring
part#1 direct link: https://www.youtube.com/edit?o=U&video_id=mBCLSxytkeM
[video]https://www.youtube.com/edit?o=U&video_id=mBCLSxytkeM[/video]
part#2 direct link: https://www.youtube.com/edit?o=U&video_id=_N_m2g8jlho
[video]https://www.youtube.com/edit?o=U&video_id=_N_m2g8jlho[/video]
Thanks Elfster. Cheers to better health and a speedy recovery!
I will add to this - a gas pressure curve for rifle barrel tapped gas has 3 critical aspects:
1. How long the bullet has been in the barrel before gas begins to flow into the operating system.
2. What the pressure of the gas is as it enters the operating system.
3. How long the dwell time is after the bullet has passed the gas port.
So it is true that a +2 gas system on a 22" barrel has similar dwell times to a 20" barrel with rifle gas, the +2 gas system will have a lower port pressure as well as more time between cartridge ignition and bolt opening. I would wager that a 22" or 24" +2 barrel is more reliable in every way than a 20 or 18" barrel with rifle gas.
Adjustable gas blocks can mitigate the pressure issue but not the other two.
Just to follow up I purchased the jp barrel,bolt, adjustable gas block and operating system. It feeds 100% with everything I tried in it. The only thing I’m not crazy about is the carbon fiber lancer hand guard. It’s very lightweight and good looking but isn’t very solid. To as accurate as I could have hoped with 130 prime.
Just to follow up I purchased the jp barrel,bolt, adjustable gas block and operating system. It feeds 100% with everything I tried in it. The only thing I’m not crazy about is the carbon fiber lancer hand guard. It’s very lightweight and good looking but isn’t very solid. To as accurate as I could have hoped with 130 prime.
I will add to this - a gas pressure curve for rifle barrel tapped gas has 3 critical aspects:
1. How long the bullet has been in the barrel before gas begins to flow into the operating system.
2. What the pressure of the gas is as it enters the operating system.
3. How long the dwell time is after the bullet has passed the gas port.
So it is true that a +2 gas system on a 22" barrel has similar dwell times to a 20" barrel with rifle gas, the +2 gas system will have a lower port pressure as well as more time between cartridge ignition and bolt opening. I would wager that a 22" or 24" +2 barrel is more reliable in every way than a 20 or 18" barrel with rifle gas.
Adjustable gas blocks can mitigate the pressure issue but not the other two.
^^This..
You don't arbitrarily need a +2 on everything. I run a rifle length gas tube on a 22" barrel without hiccup. I know of a handful I have built with 20 and 22" barrels with rifle length gas systems that have zero issues. If I had a 24" barrel I would absolutely want a +2 length. Even the 22" wouldn't hurt. You don't need one for 18 and 20" barrels.
^^ I think this is a great general rule of thumb based on my research. That said, a rile+2 is mandatory for my 22" build. I consider rifle+2 an insurance policy well worth having assuming you are buying new.
the main key is the adjustable gas block more than anything.. i have a custom made from the ground up mega 6.5 AR with a 22" barrel with an extra 2" gas and IMO it makes for a super smooth shooting AR and is my crown jewel in my collection... with the custom brake = shoots damn near like a .223... i was in the middle of making a complete series on my MEGA 6.5 creedmoor when i found out about my whole cancer ordeal..... which i hope to pick up soon late spring
part#1 direct link:
part#2 direct link:
Does he use a can?My buddy has a 14.9” 6.5 with rifle length gas. It’s important to have a long gas system for this caliber.
SLR Sentry 8 or Superlative. I have used both and they both work well.Glad I stumbled into this thread!
I have a 6.5cm barrel being spun up at Compass Lake Engineering. Going with a 24" Bartlein 8 twist. I just followed up with them to see if I can have it cut for a +2" gas system based on this thread.
I will be running it with a TB Ultra 7 suppressor. Any recommendations on an adjustable .875" gas block?