View Full Version : 11.5" w/ 0.080 gas port
Hey guys,
I'm gearing up to do my first pistol build and I bought a GMR 11.5" nitride barrel. Emailed them and was told it has a .080 gas port. Is this going to be an issue? Thanks.
You'll probably want to dial that port down at least 10 thou...
Bob Sacamano
11-08-17, 15:17
I would send it back.
Unacceptable. .071 is nice with no can. We've been choking them down to .067 for suppressed use... although they will run unsuppressed at .067... it's just pushing it a little.
Sorry OP, I just need to ask. Are these oversized ports so people can run cheap Wolf ammo?
An 11.5" with a .076 will run almost all ammo on the market without being massively overgassed. Anything larger than that is 100% unnecessary.
Sorry OP, I just need to ask. Are these oversized ports so people can run cheap Wolf ammo?
I think so. The Industry has taken forever to figure this shit out. For YEARS the solution was extractor tension/O rings... all kinds of retarded crap like this... Then the attention went to heavy buffers. This was much less retarded... but still not the best solution. (I'm not saying the CAR buffer is acceptable... just that an H3 or H4 carbine buffer is too heavy, and the gassing needs to be addressed)
Now we are finally seeing some attention to correctly gassing the guns from the get go. Sionics as an example. I think their 11.5 reduced gas port is the best AR barrel you can get right now. Pappabear bought one, and after seeing the quality of the Chrome lining and the way it shot, I bought one too.
Unless you run in the rare combination that may include extreme low temps with guns running dried and fouled, you really do not want to port for that. I would rather see a regular M16 chamber and bore with a .067" port for this that has action mass options for those extremes than enlarging the base port.
How did they come to spec it to that size?
Does it matter now?
Why didn’t you ask before you bought it?
My 11.5” .075” is a little over gassed (measured by caliper) so I would expect a .08 to be quite a bit excessive.
Why don’t you tell us if it’s a problem after you get some rounds down range? You are pot- committed.
SeriousStudent
11-08-17, 21:47
....
Now we are finally seeing some attention to correctly gassing the guns from the get go. Sionics as an example. I think their 11.5 reduced gas port is the best AR barrel you can get right now. Pappabear bought one, and after seeing the quality of the Chrome lining and the way it shot, I bought one too.
I love mine. It runs like a champ, suppressed and unsuppressed. No changing springs, buffers or other monkeyshines. Just feed it quality ammo and use reliable mags.
I love mine. It runs like a champ, suppressed and unsuppressed. No changing springs, buffers or other monkeyshines. Just feed it quality ammo and use reliable mags.
Are you suing the A5 system? If so what buffer?
I️ am planning on a. Sionics 11.5 build soon
Sent from my iPhone using Tapatalk
What sort of accuracy has the Sionics 11.5" RGP barrel been throwing? I read the thread about them and people were talking about them running well, but I didn't see any accuracy reports.
Mine is set up with an LMT E-Carrier, A5H3 and Sprinco green spring.
I love mine. It runs like a champ, suppressed and unsuppressed. No changing springs, buffers or other monkeyshines. Just feed it quality ammo and use reliable mags.
nightchief
11-09-17, 06:56
Mine is set up with an LMT E-Carrier, A5H3 and Sprinco green spring.
I'll third the love of this barrel. I'm also running mine with an LMT e-carrier and A5H3 with thee green spring. I run it both suppressed and unsuppressed. After some initial issues with mating the barrel extension to certain brands of uppers, its now run close to 1000 rounds with no problem (except one blown primer that I attribute to the ammo). It can get a little gassy when suppressed, especially with 556, if shooting multi round strings at a fast pace. No gas unsuppressed.
I've gotten about 2 1/4" groups at 100 yards shooting supported using an Aimpoint and CBC 62gr 556. I haven't tried to shoot groups with any match ammo.
What sort of accuracy has the Sionics 11.5" RGP barrel been throwing? I read the thread about them and people were talking about them running well, but I didn't see any accuracy reports.
I don't remember stacking holes when I zeroed mine. But I have an Aimpoint. I think my final POI group was just over MOA. We've never put magnified optics on ours to really test them out since that's not their purpose.
gunnerblue
11-09-17, 10:59
What sort of accuracy has the Sionics 11.5" RGP barrel been throwing? I read the thread about them and people were talking about them running well, but I didn't see any accuracy reports.
If I had to guess, I’d say most are not buying these barrels with long-range precision in mind. I haven’t bothered to do any load development with mine, just zeroed at 100 yards with a T1 and 62 gr Gold Dots. IIRC, the final group was ~1.5 MOA. I’m using mine with an A5 RE, A5H3 buffer and SiCo Omega.
You'll probably want to dial that port down at least 10 thou...
Yeah, best way to go about doing that?
I bought the barrel before I was informed about gas port size. I won't buy a barrel without asking first from no on, however, I also don't know what the optimal sizes are for barrel/gas system length.
Moreover, I know that the barrel will work as it is -however, I would like to build the best I can with what I've got.
Yeah, best way to go about doing that?
I bought the barrel before I was informed about gas port size. I won't buy a barrel without asking first from no on, however, I also don't know what the optimal sizes are for barrel/gas system length.
Moreover, I know that the barrel will work as it is -however, I would like to build the best I can with what I've got.
A very good way is with our BRT Micro Tune Gas Block
Pick the right size, install and forget about it.
http://www.blackrivertactical.com/concrete5/store/#!/BRT-MicroTUNE-Gas-Block-750/p/21597560/category=6464009
If I had to guess, I’d say most are not buying these barrels with long-range precision in mind. I haven’t bothered to do any load development with mine, just zeroed at 100 yards with a T1 and 62 gr Gold Dots. IIRC, the final group was ~1.5 MOA. I’m using mine with an A5 RE, A5H3 buffer and SiCo Omega.
I understand that long range precision is not the goal of this type of barrel and do not have any such expectations. That said, accuracy is an important performance metric for a barrel, and is still a consideration when comparing to other barrels.
SeriousStudent
11-09-17, 20:31
Are you suing the A5 system? If so what buffer?
I️ am planning on a. Sionics 11.5 build soon
Sent from my iPhone using Tapatalk
Mine has a Sionics NP3 BCG, Vltor A5H3 buffer and a green Sprinco buffer spring, as Doctor Iraqgunz prescribed for me.
It runs like a scalded dog.
A very good way is with our BRT Micro Tune Gas Block
Pick the right size, install and forget about it.
http://www.blackrivertactical.com/concrete5/store/#!/BRT-MicroTUNE-Gas-Block-750/p/21597560/category=6464009
If I live close enough, do you let people swing by and pick up parts?
Just got an email back from Mike at GMR. I had asked what gas block setup they recommend and why they chose the .080 gas port.
He responded back that they don't recommend any particular gas block because they don't build rifles and that they would be unable to comment on why they chose the gas port size they use.
Should I look into returning the barrel or just go with Clint's gas block?
I would not accept that.
This. That’s really unacceptable from someone who makes... anything, to not be able to explain a specification.
Next thing they tell you, they can’t comment on what their chamber spec is or why?
stevenravenscroft
11-16-17, 09:59
I would be pissed and take my buisness somewhere else.
Already bought it and called em up to return it and there's a 20% restocking fee. Looks like the customtune gas block is the best solution.
I won't be buying the Green Mountain Rifle in the future.
stevenravenscroft
11-17-17, 13:42
Already bought it and called em up to return it and there's a 20% restocking fee. Looks like the customtune gas block is the best solution.
I won't be buying the Green Mountain Rifle in the future.
That sucks. Sorry to hear your bad luck
Glad I saw this so I dont use them for anything. You can always send it back and dispute it with you card.
In fairness, most SBR barrels are made with retardedly large ports. We choked down almost every short barrel we run with insertable ports.
To a point yes, but the insert is more of a band aid than a more preferable solution to the issue with the negatives involved. I can see the use for a moderately gassed base that meets realistic criteria(s) for use as a possible solution, but many attempt to use an insert or external adjustment to restrict gas in some systems with a less than preferable base that results in an excess of negatives overall for the lifecycle of the system.
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