Gas system question - Page 2

bfoosh006 · September 26, 2016, 02:38 PM

I should add... ( IMHO ) most carbines are over gassed, with a larger gas port.

Reliable operation with a dirty rifle , or any powered ammo is an important feature.

And having an "over" sized gas port "helps" muscle past problems.

And... there seems to be no set gas port standard size for the various manufacturers to adhere to.

Just a vague... this works best...

And on a somewhat related to this issue topic...

Also, under NO circumstances should you fire Hornady Superformance ammo in your carbine.... The powder used has a slower burn and produces excess port pressure.... causing issues even worse then yours... ( blown primers etc. )

Txbonecollector75 · September 26, 2016, 03:04 PM

Ok so to fix my over gassing problem I should get an adjustable gas block and tune it to my hand load? Right now I'm hand loading .223 ammo but when I start loading up my 5.56 NATO rounds will I have to readjust my gas block or leave it alone so I can fire both .223 & 5.56 NATO?

bfoosh006 · September 26, 2016, 03:41 PM

You don't have to buy an adjustable gas block... try the H3 and new spring, first.

Then look over the newly fired 5.56 factory ammo that used the H3 and spring... it should look less abused then the "Standard" buffer brass.

And try some of your .223 reloads.

It really doesn't take a lot to fix your issue... so most likely the heavier buffer and new spring will do it.

If the H3 and new spring don't help... then consider an adjustable gas block.

The advantage ( and disadvantage ) to an adjustable gas block is tailoring your gas level.... so you might need to adjust it , high and low, more then needed.

Adjustable gas blocks really are for guys running 3 gun, shooting the same load / ammo all the time. They tailor the cycling to as little as needed, in order to stay on target and make quicker following shots.... NOTE they "tune" a hair over what is needed for reliability.... again using ammo with the same gas curve produced from burning the powder ( IE fast powder v. slow powder...remember the Horn. Superformance ... really slow gas curve.. creating much more volume of gas )

As, over gassed folks use an adjustable gas block to help "solve" over gassed barrels.

With the H3 and new spring you should notice a difference. promptly.

It really doesn't take very much ( remember those milliseconds ) to "alter" your cycling.

If any of this seems confusing... it is.

Do not be afraid to continue to ask questions.

There are a lot of variables involved in making a gas gun work well... ( The M1A is much more fussy port pressure wise )

Metal god · September 26, 2016, 04:00 PM

I agree with bfoosh 100% maybe a full auto carrier if you have the post ban model .

stagpanther · September 26, 2016, 04:21 PM

Are you sure your headspace is OK? I've seen a couple brand new rifles that were barely in compliance of a no-go (OK--I'll admit, even one I built). A Hornady gauge that shows distance to engaging lands is not going to tell you what your headspace is. If nothing else--download the SAAMI specs for the case and measure what you have from the "problem" cases. A certain amount of expansion is normal--actually necessary--but then the case should "snap back" pretty close to what it started out with. Between the play between your bolt face and the case head face--and the "slack" in chamber dimensions--it's pretty common to stay within compliance with roughly .005 to .006 inches in total "play." Once you go past that you're looking at potential problems--especially over time--not the least of which might be a case failure at the head. It really would be a great help if you could take some better photos and post them--use your cellphone if ya have to.

marine6680 · September 26, 2016, 04:54 PM

The good thing about an H3, is that if you have a standard buffer too, you can combine them into any combination. So if H3 is too much, then make an H2 or H. But I have seen it said that an extra power spring and H3 buffer are the best combination for running only 5.56 out of a 16in barrel with carbine length gas system.

If your problem is severe, a buffer alone may not be enough, and an adjustable block may be needed.

If the H3 solves the problem, and it runs cheap steel cased ammo properly, then I would say that you are good to go.

If the H3 is too much, but an H2 works the same way, then good... If it exhibits only a little over gassing with 556, then you are likely good too.

If it really bothers you, then get an adjustable block, and tune it to run cheap ammo with an H buffer.

Then you are likely to be fine for 5.56 as well, but a little higher than optimal. But reliability with standard ammo and 5.56 should be good.

243winxb · September 26, 2016, 06:11 PM

adjustable gas block http://www.hornady.com/ammunition/su...rated-firearms

Quote:

the gun is still in the process or firing while it’s trying to extract the cartridge case.

Does not have to be Superformance ammo.

stagpanther · September 26, 2016, 06:39 PM

Quote:

adjustable gas block http://www.hornady.com/ammunition/su...rated-firearms
Quote:
the gun is still in the process or firing while it’s trying to extract the cartridge case.
Does not have to be Superformance ammo.

The constant in most of these articles being a rifle length gas system on a long barrel--which doesn't help a whole lot when I suspect the vast majority of the market is 16" carbine systems. What really cooks my goose is that my 7.5" AR pistol has yet to show any issues with a wide range of ammunition--so I don't think there is necessarily a direct linear relationship between barrel/gas system length and over-gassing--I suspect (maybe?) that bullet exit from muzzle in relation to exhaust "pass through" the bore is a factor--but don't know for sure.

rickyrick · September 26, 2016, 07:00 PM

I have a 24" barrel with a rifle gas system and it functions just fine it seems... but I've wondered about that foot of barrel past the gas port and how it affects the system.

marine6680 · September 26, 2016, 08:56 PM

Stag... That's called "dwell time"

It is a very important part of the timing and how the rifle behaves.

A bigger gas port allows higher pressure and more gas to reach the bolt carrier.

A longer dwell time will increase the amount of gas that reaches the carrier.

This is why carbine length gas systems are known for being over gassed. As the dwell time in a 16in barrel is longer than it would be in a standard military 14.5in barrel.

If all you did was copy the gas port size from an m4, you get over gassing.

Inversely, if you put a mid length gas system on a 14.5in barrel, and keep the gas port the same size as a typical mid length system port... You have too little gas, and poor reliability.

This is why companies like BCM and DD have good reputations, they took the time to experiment and test different gas port sizes for the different barrel length and gas system length combinations.

And cheap budget manufacturers tend to have issues with gassing, usually erring on the side of too much, as they just copy and past the design, or source parts and just make spec requests based on available tech data... They don't do testing to fine tune the product, if it works, then it's good to go as is.

Metal god · September 26, 2016, 11:41 PM

DING DING DING ^^^^^^^ winner

September 26, 2016, 02:38 PM	#26
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	I should add... ( IMHO ) most carbines are over gassed, with a larger gas port. Reliable operation with a dirty rifle , or any powered ammo is an important feature. And having an "over" sized gas port "helps" muscle past problems. And... there seems to be no set gas port standard size for the various manufacturers to adhere to. Just a vague... this works best... And on a somewhat related to this issue topic... Also, under NO circumstances should you fire Hornady Superformance ammo in your carbine.... The powder used has a slower burn and produces excess port pressure.... causing issues even worse then yours... ( blown primers etc. ) Last edited by bfoosh006; September 26, 2016 at 02:44 PM.

September 26, 2016, 03:41 PM	#28
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	You don't have to buy an adjustable gas block... try the H3 and new spring, first. Then look over the newly fired 5.56 factory ammo that used the H3 and spring... it should look less abused then the "Standard" buffer brass. And try some of your .223 reloads. It really doesn't take a lot to fix your issue... so most likely the heavier buffer and new spring will do it. If the H3 and new spring don't help... then consider an adjustable gas block. The advantage ( and disadvantage ) to an adjustable gas block is tailoring your gas level.... so you might need to adjust it , high and low, more then needed. Adjustable gas blocks really are for guys running 3 gun, shooting the same load / ammo all the time. They tailor the cycling to as little as needed, in order to stay on target and make quicker following shots.... NOTE they "tune" a hair over what is needed for reliability.... again using ammo with the same gas curve produced from burning the powder ( IE fast powder v. slow powder...remember the Horn. Superformance ... really slow gas curve.. creating much more volume of gas ) As, over gassed folks use an adjustable gas block to help "solve" over gassed barrels. With the H3 and new spring you should notice a difference. promptly. It really doesn't take very much ( remember those milliseconds ) to "alter" your cycling. If any of this seems confusing... it is. Do not be afraid to continue to ask questions. There are a lot of variables involved in making a gas gun work well... ( The M1A is much more fussy port pressure wise ) Last edited by bfoosh006; September 26, 2016 at 04:01 PM.

September 26, 2016, 04:00 PM	#29
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	I agree with bfoosh 100% maybe a full auto carrier if you have the post ban model . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

September 26, 2016, 04:21 PM	#30
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,789	Are you sure your headspace is OK? I've seen a couple brand new rifles that were barely in compliance of a no-go (OK--I'll admit, even one I built). A Hornady gauge that shows distance to engaging lands is not going to tell you what your headspace is. If nothing else--download the SAAMI specs for the case and measure what you have from the "problem" cases. A certain amount of expansion is normal--actually necessary--but then the case should "snap back" pretty close to what it started out with. Between the play between your bolt face and the case head face--and the "slack" in chamber dimensions--it's pretty common to stay within compliance with roughly .005 to .006 inches in total "play." Once you go past that you're looking at potential problems--especially over time--not the least of which might be a case failure at the head. It really would be a great help if you could take some better photos and post them--use your cellphone if ya have to. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

September 26, 2016, 11:41 PM	#36
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	DING DING DING ^^^^^^^ winner __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

September 26, 2016, 03:04 PM	#27
Txbonecollector75 Member Join Date: July 28, 2016 Posts: 32	Ok so to fix my over gassing problem I should get an adjustable gas block and tune it to my hand load? Right now I'm hand loading .223 ammo but when I start loading up my 5.56 NATO rounds will I have to readjust my gas block or leave it alone so I can fire both .223 & 5.56 NATO?

September 26, 2016, 04:54 PM	#31
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	The good thing about an H3, is that if you have a standard buffer too, you can combine them into any combination. So if H3 is too much, then make an H2 or H. But I have seen it said that an extra power spring and H3 buffer are the best combination for running only 5.56 out of a 16in barrel with carbine length gas system. If your problem is severe, a buffer alone may not be enough, and an adjustable block may be needed. If the H3 solves the problem, and it runs cheap steel cased ammo properly, then I would say that you are good to go. If the H3 is too much, but an H2 works the same way, then good... If it exhibits only a little over gassing with 556, then you are likely good too. If it really bothers you, then get an adjustable block, and tune it to run cheap ammo with an H buffer. Then you are likely to be fine for 5.56 as well, but a little higher than optimal. But reliability with standard ammo and 5.56 should be good.

September 26, 2016, 07:00 PM	#34
rickyrick Senior Member Join Date: March 15, 2010 Posts: 8,238	I have a 24" barrel with a rifle gas system and it functions just fine it seems... but I've wondered about that foot of barrel past the gas port and how it affects the system.

September 26, 2016, 08:56 PM	#35
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	Stag... That's called "dwell time" It is a very important part of the timing and how the rifle behaves. A bigger gas port allows higher pressure and more gas to reach the bolt carrier. A longer dwell time will increase the amount of gas that reaches the carrier. This is why carbine length gas systems are known for being over gassed. As the dwell time in a 16in barrel is longer than it would be in a standard military 14.5in barrel. If all you did was copy the gas port size from an m4, you get over gassing. Inversely, if you put a mid length gas system on a 14.5in barrel, and keep the gas port the same size as a typical mid length system port... You have too little gas, and poor reliability. This is why companies like BCM and DD have good reputations, they took the time to experiment and test different gas port sizes for the different barrel length and gas system length combinations. And cheap budget manufacturers tend to have issues with gassing, usually erring on the side of too much, as they just copy and past the design, or source parts and just make spec requests based on available tech data... They don't do testing to fine tune the product, if it works, then it's good to go as is.