View Full Version : BRT custom tune gas port vs heavier buffer
I have been reading some posts lately about Noveske barrels being over gassed.
I have a Noveske 16" mid that honestly feels less gassy than a BCM 14.5 mid. I run A5H3 buffers in both. My least gassy rifle is Colt 14.5 carbine with an A5H2. I chose those buffers based in the rifle's ability to get bolt lock with .223 ammo. I never actually tried an A5H4 in either of those rifles yet.
Anyway, I have another Noveske 14.5 barrel on the way. They're the only game in town for mid-weight CHF barrels, and my 16" rifle is clearly the most accurate that I own. Fully taking into account that I have yet to shoot the new barrel I was debating the merits of using a BRT custom tune gas port to restrict the gas flow or just using heavier buffers.
Any experience or advice is welcome.
If anyone is curious the build will consist of a BCM lower with VLTOR A5 receiver extension, VLTOR MUR uppper, Noveske 14.5 barrel with pinned PA EFAB brake, and Geissele MK14 handguard.
My experience points to properly setting the gas flow and using the A5H2. Heavier buffers start to push the AR around more than needed as the action cycles.
EzGoingKev
02-24-18, 12:45
My experience points to properly setting the gas flow and using the A5H2. Heavier buffers start to push the AR around more than needed as the action cycles.
So I have an older Colt 6920 with the A5 system in it. It runs 100% with the A5H3 and Sprinco green spring. I could probably go up to the A5H4 buffer without issues. Are you saying I should swap the A5H2 back in and tune the exhaust port?
Tuning with mass is easy to do, but excessive moving mass makes the sights jump around more.
Also, the range of adjustment is somewhat limited.
For example, the difference in spring energy from the lightest to heaviest buffer is only around 10% or so.
That is roughly the same as changing the port by two sizes.
The range of adjustment using ports is far wider than buffers and has none of the drawbacks of heavy buffers.
When suppressors are involved, heavy buffers can help slow down the cycling, but won't meaningfully reduce gas blowback and gas to face issues.
Only restricting the gas will accomplish that.
EzGoingKev
02-24-18, 13:55
I believe mass also keeps the bolt carrier group from bounce back.
So my basic question is, as it comes from Colt is my 6920 slightly overgassed?
So I have an older Colt 6920 with the A5 system in it. It runs 100% with the A5H3 and Sprinco green spring. I could probably go up to the A5H4 buffer without issues. Are you saying I should swap the A5H2 back in and tune the exhaust port?
Ideally yes, if you wish to further fine tune your AR. Heavier buffers will start pushing your AR around and increase the time and movement it takes to get back on target. However, unless the recoil is excessively sharp (the sign that the buffer is bottoming out too hard) or you're not satisfied with how you're getting back on target, I don't think it's worth worrying about.
I've been playing with a suppressed 11.5" upper that uses an SLR adjustable gas block. I first tested it with a carbine RE, carbine, H and H2 buffers and Colt carbine action spring. Then it was tested it with an A5 RE, A5H2 buffer and Sprinco green spring. The SLR is click adjustable and each click is one third of a turn. I set the gas block so it would lock back on the last shot with the carbine buffer. Closing the gas block one click resulted in the AR ejecting, but not locking back. In each test, the setting on the gas block didn't have to be changed. Closing the gas block one click resulted in the AR ejecting but not locking back regardless of buffer.
What I did notice is that recoil was sharpest with the lightest buffer (carbine). It was smoothest with the heaviest buffer (A5H2). The Aimpoint dot moved off the target the least when shooting with the A5H2.. I didn't test heavier buffers because I didn't have any. However, the greater the ratio of reciprocating mass to static mass, the more the reciprocating mass (BCG & buffer) will push the static mass (rifle) around. It's that opposite but equal thing Newton foisted upon us. Don't just take my word for it, however. Switching from an A5H2 buffer to an A5H3 buffer won't result in your AR suddenly being pushed around like a first grader on the sixth grade playground. Test it for yourself.
So, what does this mean to you and your Colt? The way I see it, you have three paths before you.
1)If It Ain't Broke, Don't Fix It
If your AR is working fine, don't worry about it. If the buffer isn't bottoming out too hard and your satisfied with how quick you get back on target, press on.
2)I'm Not Happy With My Performance Shooting My AR This is a two part path-
A) The Easy Button- The easiest is to simply try the heavier buffer. The best result is that the heavier buffer works for you. Either you don't notice any extra push, or it's small enough that it's not worth worrying about. It's a win for you with the added bonus you can say "That Mistwolf is a nice guy, but he's full of it." If it doesn't, it's still a win for you because you shot the rifle and found out for yourself instead of just reading about it on the internet. However, I get to be smug.
B)The Hard Way-The harder path (the one you take after experimenting with heavier buffers) is to try an SLR adjustable gas block, or the BRT custom tune gas port. Both are good choices. The SLR is easier to adjust, the BRT is simpler in design and costs less. Adjusting your gas flow will let you determine for yourself if the A5H2 will give you optimal results or not. Either way, you'll be able to adjust the gas for best performance with each buffer (and spring, if so inclined). Then, you can come back and tell me I'm full of it, or to wipe that smug grin off my face. Choosing this path will allow you to better tune your AR.
3)Curiosity Killed The Cat
Your AR works fine, but you have a burning desire to find out if you can make it a little better. Again, it's a two part path. To save time typing, I will refer you to Options A) & B) from 2)I'm Not Happy With My Performance With My AR. Apply "Full of it" or "Wipe Off That Smug Smile" as needed.
Mistwolf / Clint,
Thanks for your replies. I try to avoid the gun forum trap of over thinking stuff that doesn't matter, but you guys helped confirm what I was thinking. I should have mentioned in my original post that I have no intention of ever shooting this gun suppressed, but I'll be getting a BRT insert.
On a side note. I was planning on getting a Colt BCG if I can find one in stock or a BCM. However, Centurion Arms has pretty good prices on their BCG's especially with mil discount. I'm not afraid to spend money on quality, but if the Centurion is mil-spec and the same quality as BCM it's a no brainer. Anyone have insight on that?
everready73
02-24-18, 19:59
Centurion BCG are good stuff, but if you want a really good deal on a Colt, Shark arms has them for $125 which is the cheapest I have found. There website is pretty basic and you have to call in your order, but I have ordered from them before and they are GTG. Really good source for other Colt parts as well
Everready,
Thanks for the tip! I'm going to be placing an order with them.
I'm curious how they are selling them so cheap, though. Other vendors sell Colt BCGs for $180-$200.
everready73
02-24-18, 20:13
Yes I was surprised at the pricing. Heard about them on the other forum and have ordered several times with no issues
I have a Noveske 14.5" ML and it is on the gassy side. I'm currently running a regular RE with a H3 buffer. I believe the gas port size is .080.
I have a Noveske 14.5" ML and it is on the gassy side. I'm currently running a regular RE with a H3 buffer. I believe the gas port size is .080.
Sounds like a couple sizes larger than needed.
A custom tune gas port can fix it right up.
My experience points to properly setting the gas flow and using the A5H2. Heavier buffers start to push the AR around more than needed as the action cycles.
Went out and tried running a rifle set up for an A5H2 with an A5H3. The muzzle dip was pretty easy to note after getting used to the A5H2. I was pretty surprised.
Back in topic, I'll be doing a gas port in an overgassed barrel rather than go up a buffer weight.
Sounds like a couple sizes larger than needed.
A custom tune gas port can fix it right up.
It's a Factory upper with a pinned/welded BattleComp:(
Unpinning a pinned/welded muzzle device with a dremel is actually much easier than people think. Just go slow, and only remove as much metal as necessary to get the pin to loosed up.
Unfortunately you will sacrifice your BattleComp.
Clint,
I'm glad you're on this thread. I have read quite a bit about people talking about gas port erosion.
How big of a problem is that really, and how do your gas port inserts affect it?
I have shot out a few barrels, and as far as I know gas port erosion has never been an issue.
Unpinning a pinned/welded muzzle device with a dremel is actually much easier than people think. Just go slow, and only remove as much metal as necessary to get the pin to loosed up.
Unfortunately you will sacrifice your BattleComp.
Yeah, I'm not getting rid of a Noveske marked Battlecomp hence the frowny face in my post.
It's a Factory upper with a pinned/welded BattleComp:(
Yeah, I'm not getting rid of a Noveske marked Battlecomp hence the frowny face in my post.
One option is that case is a two piece clamp on gas block.
https://yhm.net/specter-gas-block.html
Clint, what about sliding the existing gas block forward and drilling and tapping the barrel gas port to accept the micro port?
Clint, what about sliding the existing gas block forward and drilling and tapping the barrel gas port to accept the micro port?
Hmm,
Might be possible, but seems like a theoretically good method to actually ruin an otherwise good barrel.
Bob Sacamano
03-04-18, 14:35
With the current trend from many barrel makers, prob would not even need to drill it, just run a tap through the gas port hole.
BufordTJustice
03-04-18, 14:46
Hmm,
Might be possible, but seems like a theoretically good method to actually ruin an otherwise good barrel.
I agree with Clint.
THEORETICALLY it should work. But it makes my butthole tighten up a whole lot.
Sent from my iPhone using Tapatalk
It's a Factory upper with a pinned/welded BattleComp:(
We've got a prototype adjustable gas tube that should work well with the pinned battle comp.
It drops right in without removing the gas block.
Bob Sacamano
03-18-18, 22:22
Very interesting. Have a Noveske 14.5 with a pinned BC in the parts box. Would be nice to put it back into service.
I thought I'd post an update for the gun that inspired me to make this thread.
I got her put together on Friday and ran a few hundred rounds through it today. I've concluded that I was likely over thinking the Noveske being over gassed internet talk. I measured the gas port at .080" compared to my 14.5 BCM upper that measures .077". I'm not an engineer, and have no idea how significant that is, but it feels good shooting it with an A5H2.
Also, I'm now in love with the Precision Armament EFAB.
Glockman1968
03-25-18, 17:43
What would the drawback be, if any, of going to a .073 from a .076 in a 16in middie?
Clint, it's in your block with your port... if that helps.
When I first put it in, I starting playing the spring/buffer game using .223 PMC Bronze and 5.56mm Magtech 77s.
Preface this with no malfs of any kind during this process.
Using the green spring and the -2, the .223 would eject to 3 and the 5.56 2ish. Went to the -3, and they moved forward 1 o clock respectively.
Now think maybe the -2 and a smaller port would get it where I'd like it.
the .073 should run nicely.
We've got a prototype adjustable gas tube that should work well with the pinned battle comp.
It drops right in without removing the gas block.
Sounds very interesting.
Hmm,
Might be possible, but seems like a theoretically good method to actually ruin an otherwise good barrel.
As a guy who makes a living drilling holes in things, that's what I'd do. Drill only part way, finish tapping with a flat bottom tap and if the Microport stood a little proud, I'd blend it. The use of a drill stop will minimize the risk and would be easier than removing a pinned muzzle device.
Very interesting. Have a Noveske 14.5 with a pinned BC in the parts box. Would be nice to put it back into service.
Sounds very interesting.
Feel free to PM for a coupon code if you'd like to try out some EZTUNE prototypes (https://www.blackrivertactical.com/concrete5/store/#!/BRT-EZTUNE-Gas-Tube-Midlength/p/103167236/category=6464009).
Installed a BRT port in a Centurion gas block with an oversized gas block port hole. Worked fine at first until pressure pushed the insert up into the gas tube creating a short stroke situation. Be sure you don't induce a point of failure, including cold temp operation.
Installed a BRT port in a Centurion gas block with an oversized gas block port hole. Worked fine at first until pressure pushed the insert up into the gas tube creating a short stroke situation. Be sure you don't induce a point of failure, including cold temp operation.
Let's get to the bottom of this. PM sent.
Centurion gas block port hole is larger than normal I believe, as in the supplied drill bit went right in but wasn't loose per se so I thought it would be ok. It wasn't. After a few dozen rounds the insert inserted itself into the gas tube creating a nearly shut off gas system with resulting short strokes. The account was [redacted], so look for our correspondence. I elected to just go with the Centurion setup unmodified, and now that rifle with a dragon brake and H buffer is the flattest shooting rifle we have. Rings are almost gone, but it functions great.
You offered to explore corrective options at that time, I elected to stay stock Centurion for reliability and hassle reasons and it's worked out fine.
Clint,
What is the expected service life of your new gas tubes? Should they last the life of the barrel?
vicious_cb
03-30-18, 11:02
I thought I'd post an update for the gun that inspired me to make this thread.
I got her put together on Friday and ran a few hundred rounds through it today. I've concluded that I was likely over thinking the Noveske being over gassed internet talk. I measured the gas port at .080" compared to my 14.5 BCM upper that measures .077". I'm not an engineer, and have no idea how significant that is, but it feels good shooting it with an A5H2.
Also, I'm now in love with the Precision Armament EFAB.
That is overgassed. Just because a large portion of the industry uses ≥.080" gas ports on midlengths does not make them right.
Its just like 15 years ago when the only guys doing mil-spec gas ports on their carbine barrels were Colt and LMT.
Just ordered several BRT EZTUNE gas tubes (carbine) to try out on some legacy 10.5" and 11.5" non-adjustable uppers with suppressors.
Threadjack...
Clint, what size EZTUNE gas tube (midlength) port sizes would you recommend for 14.5" midlength barrels with 50/50 suppressor use and only brass ammo?
Tube arrived and installed today. Rifle is noticeably less gassy, ejection 3/4(usually 2 o'clock before). I noticed the tube/order was switched from .073 to .076, but it functions fine, locks back last round, easier to keep on target, less impulse to dot my eye with my acog, overall a win.
Thanks for working it out...
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