Intermediate and Rifle Length Gas

[EO3]

Hey guys. I'm just full of questions here. Trying to learn as much as I can. I've been trying to read up on intermediate and rifle length gas systems, especially in regard to how they work with a 16" barrel. I have a 14.5 mid-length that is very smooth-shooting, and I'm wondering about how intermediate, and even rifle length gas systems are on a 16". If anyone has experience with these, I'd like to know what you've experienced. Additionally, if you know of places offering these, let me know. I've found a few, but I don't know all of the places to look for who makes these.

Thanks again for any information or help. Mostly just trying to learn as much as I can!

[UWone77]

I've been shooting Rainier Rock Creek Match barrels, 16" with Rifle Gas, and a 12.5" with mid-length gas. Both run, but they need to be tuned.

If you want a project shooter to tune and shoot very soft, it might be something for you.

[Aragorn]

Closest I've ran is a MicroMOA 17.3" barrel with rifle gas. They're ported to work with 5.56 pressure stuff using a carbine buffer and Springco "White" spring, and a full weight bcg, and say they may not be reliable with anything under 5.56 loads.

I set mine up with an adjustable gas block and run a V7 Titanium bolt carrier and a Spike's T1 buffer with a Springco "White" spring. She's a pussycat.

The MicroMOA barrels are definitely ported small though. Even with my lightweight bcg, my gas block is running only one click from full open as that's where I've found the reliability.

No experience with a 16" on rifle gas.

[EO3]

Closest I've ran is a MicroMOA 17.3" barrel with rifle gas. They're ported to work with 5.56 pressure stuff using a carbine buffer and Springco "White" spring, and a full weight bcg, and say they may not be reliable with anything under 5.56 loads.

I set mine up with an adjustable gas block and run a V7 Titanium bolt carrier and a Spike's T1 buffer with a Springco "White" spring. She's a pussycat.

The MicroMOA barrels are definitely ported small though. Even with my lightweight bcg, my gas block is running only one click from full open as that's where I've found the reliability.

No experience with a 16" on rifle gas.

Sounds like a pretty sweet setup. I know rifle/intermediate is not common on 16" at all, but I wanted to see if anyone on here had experience or info.

[Aragorn]

Sounds like a pretty sweet setup.

It is, but I don't think I'll go through the trouble or expense (mostly the expense) of setting up another gun with a lightweight bcg. At the time I wanted the smoothest, softest, flattest shooting rifle I could make with legs to really reach out there. At least in 5.56 terms.

And that's really what I got. That said, it doesn't seem to be a HUGE improvement over a 16" middy running a heavier buffer and/or spring, and that's with both the rifle gas and low reciprocating mass in play. It's not the same as adding a brake per se. More like going from a pure flash suppressor to a sorta kinda good hybrid device.

[EO3]

It is, but I don't think I'll go through the trouble or expense (mostly the expense) of setting up another gun with a lightweight bcg. At the time I wanted the smoothest, softest, flattest shooting rifle I could make with legs to really reach out there. At least in 5.56 terms.

And that's really what I got. That said, it doesn't seem to be a HUGE improvement over a 16" middy running a heavier buffer and/or spring, and that's with both the rifle gas and low reciprocating mass in play. It's not the same as adding a brake per se. More like going from a pure flash suppressor to a sorta kinda good hybrid device.

I think I will go with a 16" middy in the end with some sort of heavier buffer and/or spring, I was just curious about what was out there in regard to the intermediate/rifle gas systems.

[schambers]

For the OP:

I think dissipator (spelling?) pattern uppers have been discussed in detail in the forum a few years ago. May be worth looking into if you are curious about non-standard gas system/ barrel length combinations.

Spoiler: You don't get much more compared to the standard combinations.

[EO3]

For the OP:

I think dissipator (spelling?) pattern uppers have been discussed in detail in the forum a few years ago. May be worth looking into if you are curious about non-standard gas system/ barrel length combinations.

Spoiler: You don't get much more compared to the standard combinations.

Speaking of dissipators, I was under the impression that those were a 16" barrel with a lo pro carbine gas system, and then a FSP mounted at a rifle length position?

[gatordev]

I think I will go with a 16" middy in the end with some sort of heavier buffer and/or spring, I was just curious about what was out there in regard to the intermediate/rifle gas systems.

Knights guns also have an intermediate gas system. I can't remember if that's what they call it, but that's essentially what it is.

[schambers]

Speaking of dissipators, I was under the impression that those were a 16" barrel with a lo pro carbine gas system, and then a FSP mounted at a rifle length position?

Your right.

Original dissipator-style rifles were tested by colt. They started with 20" barrels with rifle gas systems. The barrels were cut to 16", gas ports opened etc.

Bushmaster started selling a 16" barrel with carbine gas and rifle FSP configuration as a way to make something that was similar to colt's design but was arguably more reliable. They coined the term "dissipator" and the term stuck.

I think that in general, when people refer to a dissipator they are referring to a 16" barrel and a rifle length gas system.

[Deadwing]

I've got an 18" Noveske SPR with an intermediate length gas system. Runs like a champ with anything from el cheapo 55gr .223 to heavier NATO pressure stuff like Black Hills Mk 262. The two mid-length gas 14.5" guns i own likewise will eat anything i feed them and are generally soft shooters.

[rob_s]

"Dissipator" means a full front sight "a-frame" at the rifle position and a carbine or midlength gas tube wi low-profile gas block under the handguards.

KAC's gas tube length is proprietary and is longer than a standard mid-length. They simply took the gas tube from their .308 carbine and used it on the 5.56 version.

The further you deviate from the standard, the. Pre fiddle-fuck you endure. That goes for even the vaunted "mid-length" used by Armalite for 20+ years and popularized in the last half-decade. There seems to be a sense that if carbine is bad, and mid-length is better, then intermediate must be better still and rifle length better than that. There is a point of diminishing returns and the fiddle-fuck increases with the gas tube length, as reliability decreases.

People ask questions about what the "standard" is for the gas tubes longer than carbine. There isn't one. Truth be told, there isn't a standard for the carbine length either unless you're using a 14.5" barrel. Therein lies the problem.

[DUX]

I have a question that ties in with the OP's original query. On a rifle length gas system, with a full auto weight carrier, how heavy is "too heavy" with regard to the buffer? I ask because I have an H-Buffer in a rifle length AR but the weapon feels unbalanced to me as I have it currently setup. I was considering putting in a heavier buffer to try and balance it out but am concerned that it may slow the timing down too much and cause cyclical issues especially under rapid fire conditions. Thank you.

[Deadwing]

As a point of reference, a rifle buffer weighs 5.2oz. A carbine H buffer weighs 3.8oz, an H2 is 4.6oz, and an H3 is 5.4oz. Buy some buffers and experiment. Run the heaviest buffer that still gives you reliable operation.

*Don't quote me on those weights, but i'm pretty sure they're correct.

[rob_s]

I have a question that ties in with the OP's original query. On a rifle length gas system, with a full auto weight carrier, how heavy is "too heavy" with regard to the buffer? I ask because I have an H-Buffer in a rifle length AR but the weapon feels unbalanced to me as I have it currently setup. I was considering putting in a heavier buffer to try and balance it out but am concerned that it may slow the timing down too much and cause cyclical issues especially under rapid fire conditions. Thank you.

Don't use a buffer for balance.

[DUX]

Deadwing & rob_s, many thanks for your replies. You guys here most assuredly know a lot more about the AR platform than I do, but could you expound upon why using the buffer to balance out the recoil profile is a poor idea to pursue? PM me if need be. Thanks again guys.

[Deadwing]

Don't use a buffer for balance.

Is that what he was asking? I guess I didn't read his post closely enough. The thought never even crossed my mind.

What Rob said: don't use buffers for balance. I just assumed you were referring to the way your gun cycled.

[Joelski]

Are you looking to optimize cycling and reliability, or even the weight of the rifle to make it less nose heavy?

[DUX]

@ Deadwing & Joelski: Yes Sirs! The idea being to use the buffer as a counter weight of sorts so that while firing the barrel stays as flat as possible. I use pencil barrels exclusively paired with standard plastic handguards.

896
This is the particular build I'm referring to.

[Deadwing]

Deadwing & rob_s, many thanks for your replies. You guys here most assuredly know a lot more about the AR platform than I do, but could you expound upon why using the buffer to balance out the recoil profile is a poor idea to pursue? PM me if need be. Thanks again guys.

Buffers should be used to tune the cycle of operation not to physically balance your gun. If you want to balance it, try a heavier stock, or add weight to your existing stock.

[DUX]

@ Deadwing: Roger that. I did not make myself clear when I posted. My mistake. Thank you fella's.

[Joelski]

I'd get a B-5 or somesuch other stock with storage and fill the battery tubes with nickels to get a balance rather than mess with the buffer for that purpose.

[Joelski]

And it looks like you have the stock squared away.

[DUX]

Thank you for the reply Joelski. I'm trying soooo hard to keep the weight of this build under 7lbs. because I use a scope with it sometimes and that adds a lot of weight, and changes the balance point a great deal while carrying it, but I will indeed look into your suggestion. I think for now I'm going to throw an H3 in there and see how that balances the recoil when just using irons and walk it back from there if need be. Really appreciate the help guys. Thank you.

897
This is the same rifle with the 1.5x6 scope attached.

Errata: I think I'm going to go back to the Tapco SAW pistol grip too. I like how it makes my hand choke-up on the grip and reduces lateral "wobble" for me while firing.

[DUX]

Just to be clear, I was referring to "tuning" the rifle. I had never heard that term before but that's what I was getting at. I'm learning all the time. Cheers!