How much more muzzle velocity do you get out of a 5.56 20 inch barrel with a + 2 inch gas port barrel
- Thread starter para1505
- Start date
Then whats the purpose for them?
Thanks for the clarification that really makes since now
I also read up on articles on gas tube lengths
I also read up on articles on gas tube lengths
after shooting my 20" and my buddies 16" AR-15, I think the recoil impulse is less on the 20". Can't say for sure it isnt the extra barrel weight or something else, but I have an easier time watching impacts.
Not exactly a true statement.
One can get same velocity w/less case damage or 30-50 fps more with same case damage.
Negligible gain, yes.
Softer shooting, yes.
Yep, as mentioned above you can work in a lower pressure range with the extended gas tube. These are great for things like 6 and 6.5 CM in large frames or Valkyrie in small frames. +2 gas systems and adjustable gas blocks are all about tuning the amount of energy from the gas to cycle the bolt with enough energy to run reliably but not so much that you unlock too early or beat the system to death.
How fast are you looking to get 77s?
I don’t know, hadn’t really thought about it specifically, but I would imagine easily over 3000fps. I’ve gotten in the high 2780’s with my 18” with 77TMK’s and TAC .... so I would imagine maybe 300-400fps gain, especially if the longer barrel let me use a different powder, plus the gain from the Ackley chambering... does 3200 sound too far out?
I seriously doubt over 2950 fps, maybe 3000 fps, w/77 at mag length from a 223AI with accuracy. Might be able to push more raw velocity but not get accuracy.
23" barrel, +2 gas system, small gas port, straight 223, 77 Berger OTMs at 2840 with brass looking like it came from a bolt gun. I've found that Berger OTMs don't like being pushed hard, know I can get a bit more velocity from SMKs but the Berger shoots a bit better. I'll take the accuracy over velocity.
Only gaining about 13-17 fps / inch going longer barrel.
I don't have a 223AI in AR so I don't have first hand experience in what you'll gain going to AI. I suspect maybe 100 fps, doubt over 150 fps gain at most.
I went +3 on a .17 rem 26” shilen barrel. I also used lightweight bolt and buffer in a attempt to lower recoil as much as possible.
I was pushing the limit as even with lightweight bcg and captured spring buffer I still have not enough energy for bolt hold open last round.
it’s all good though as eventually I will chamber it for a 17/6.8 wildcat.
I was pushing the limit as even with lightweight bcg and captured spring buffer I still have not enough energy for bolt hold open last round.
it’s all good though as eventually I will chamber it for a 17/6.8 wildcat.
Port size?
Little small for a +3 gas, IMHO
If cycling enough to pickup next round but not coming far enough to lock back on empty magazine, need to open up another 4 thousands or so to lock back on empty magazine.
Last edited:
How's the +3" gas system working for you?
I'm thinking about using one on a WSM set-up with a longer barrel (24-26")
Thanks
I have a 6 ARC with an 18" barrel, the gas port is .101 in diameter with a plus 2" gas, I had to use a lightened rifle buffer and reduced power rifle spring to get it to function. The gas block is now barely opened and is the softest shooting AR that I have ever shot. Velocity is about 40 to 50 FPS faster than my other rifle length 6 ARC with the same length barrel, so their might be a slight gain. I now have a rifle with 20" barrel to compare it to, I think they will shoot about the same velocity.
Found this thread from some time ago. Will a rifle +1 or +2 help a 7 twist 20”-22” AR heavy barrel throwing 80gr-90gr projectiles? Slow enough?
Similar threads
