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Mid Length vs Carbine Length Gas System
Posted: Mon Jun 04, 2018 12:11 pm
by bblhd672
https://partner-mco-archive.s3.amazonaw ... 866983.pdf
Most of you probably know this stuff already, but I found it interesting and informative. Wished I known before I bought my AR so I could have gone with a mid-length instead of carbine.
Re: Mid Length vs Carbin Length Gas System
Posted: Mon Jun 04, 2018 12:21 pm
by Paladin
Re: Mid Length vs Carbin Length Gas System
Posted: Mon Jun 04, 2018 12:28 pm
by Bitter Clinger
It is insignificant. You will never notice any issues. Unless you buy that crappy Russian ammo with the lacquered cases
Re: Mid Length vs Carbin Length Gas System
Posted: Mon Jun 04, 2018 12:45 pm
by DEB
Bitter Clinger wrote: Mon Jun 04, 2018 12:28 pm
It is insignificant. You will never notice any issues. Unless you buy that crappy Russian ammo with the lacquered cases
Bitter Clinger, have you had problems with Russian ammo? I have personally shot several thousand rounds and have experienced no problems as have all of my friends, except for the one listed below. (Russian ammo is cheap, so can shoot more often). I have heard from others that this is an issue, but can find nobody that personally have had this issue, at least recently. One of my friends stated he had an issue about 15 years ago, as the lacquer would build up, but has not had an issue recently and now shoots it frequently. Perhaps it was from earlier lot numbers, from 10 or more years ago? Just curious if you had or seen problems recently.
Re: Mid Length vs Carbin Length Gas System
Posted: Mon Jun 04, 2018 7:58 pm
by Pawpaw
The only real difference I can see for a mid length gas system is a dubious advantage, at best. With a middy, you can use a bayonet on your rifle. With the carbine gas system, there is just too much barrel in front of the bayonet lug, so the ring won't line up with the flash hider.
I told you it was dubious.
Re: Mid Length vs Carbin Length Gas System
Posted: Mon Jun 04, 2018 8:12 pm
by Ed4032
Pawpaw wrote: Mon Jun 04, 2018 7:58 pm
The only real difference I can see for a mid length gas system is a dubious advantage, at best. With a middy, you can use a bayonet on your rifle. With the carbine gas system, there is just too much barrel in front of the bayonet lug, so the ring won't line up with the flash hider.
I told you it was dubious.
But I may have to make a bayonet charge. We should probably practice at the next match.
Re: Mid Length vs Carbin Length Gas System
Posted: Wed Jun 06, 2018 8:11 am
by Bitter Clinger
DEB wrote: Mon Jun 04, 2018 12:45 pm
Bitter Clinger wrote: Mon Jun 04, 2018 12:28 pm
It is insignificant. You will never notice any issues. Unless you buy that crappy Russian ammo with the lacquered cases
Bitter Clinger, have you had problems with Russian ammo? I have personally shot several thousand rounds and have experienced no problems as have all of my friends, except for the one listed below. (Russian ammo is cheap, so can shoot more often). I have heard from others that this is an issue, but can find nobody that personally have had this issue, at least recently. One of my friends stated he had an issue about 15 years ago, as the lacquer would build up, but has not had an issue recently and now shoots it frequently. Perhaps it was from earlier lot numbers, from 10 or more years ago? Just curious if you had or seen problems recently.
I only run factory new quality ammo from Federal, Lake City, IWI, etc. I have seen others experience fouling with the laquer coated cases in years past, but nothing recent.
Re: Mid Length vs Carbine Length Gas System
Posted: Wed Jun 06, 2018 9:01 am
by MaduroBU
Do those bolt speed difference translate into real changes in parts wear or reliability?
Re: Mid Length vs Carbin Length Gas System
Posted: Wed Jun 06, 2018 11:50 am
by The Annoyed Man
DEB wrote: Mon Jun 04, 2018 12:45 pm
Bitter Clinger wrote: Mon Jun 04, 2018 12:28 pm
It is insignificant. You will never notice any issues. Unless you buy that crappy Russian ammo with the lacquered cases
Bitter Clinger, have you had problems with Russian ammo? I have personally shot several thousand rounds and have experienced no problems as have all of my friends, except for the one listed below. (Russian ammo is cheap, so can shoot more often). I have heard from others that this is an issue, but can find nobody that personally have had this issue, at least recently. One of my friends stated he had an issue about 15 years ago, as the lacquer would build up, but has not had an issue recently and now shoots it frequently. Perhaps it was from earlier lot numbers, from 10 or more years ago? Just curious if you had or seen problems recently.
I have personally helped ....or
tried to help..... several shooters at Elm Fork range over the years who got stuck cases that wouldn’t extract while shooting Russian steel-cased ammo in their ARs. Only once or twice was I able to dislodge the case and extract it for the carbine’s owner. In one case, the rim was ripped completely off the case and the case body was stuck in the chamber - necessitating a trip to a gunsmith to fix it. I won’t use the stuff.
As the owner of both an AK and several ARs, the difference in the way they lock up, headspace, and seal under detonation is very interesting to me. I started to write a long-winded response below as to
why steel cased ammo is fine in an AK and not a great idea in an AR, but it gets pretty technical, and the post dragged on. (Did anyone here realize that Kalashnikov actually copied more of the M1 Garand’s design than the German MP-43’s design as is commonly thought?) Suffice it to say that there are very good reasons why steel-cased ammo, which is just fine in an AK platform rifle, is not the best choice for an AR platform rifle - and those reasons are not just about reliability, but also about
safety.
You may be saving some money, but youre playing with fire. Like I said, I won’t use the stuff. Given how much cheaper steel cased ammo costs for AR pattern rifles than brass-cased ammo, you’d think that the Pentagon would order its branches to begin using it. When youre talking about billions of rounds of ammo, the savings adds up quickly. But they don’t, and there are reasons - safety and reliability. If we issued AKs, it would be different.
The same was true when .308 was the NATO standard small arms cartridge. Other countries, armed with other rifles than M14s, produced steel-cased .308 for their militaries. Not the US....and it wasn’t just for reasons of national pride.
Re: Mid Length vs Carbine Length Gas System
Posted: Wed Jun 06, 2018 12:15 pm
by Abraham
TAM,
I don't know the benefits between between 'carbine vs. mid length'?
For those of us who don't know, will you provide a thumbnail sketch??
Thanks!
Re: Mid Length vs Carbine Length Gas System
Posted: Wed Jun 06, 2018 12:48 pm
by jason812
Gas systems lengths from closest to chamber are pistol, carbine, mid-length, and rifle. The farther away from the chamber, the less pressure in the gas tube to cycle the bolt, which means the slower the bolt moves. The slower the bolt moves, the easier it is on parts and recoil. That's the summary.
You can also slow the bolt down with different buffer weights and springs or an adjustable gas block. Generally you want a minimum 4" of barrel length past the gas port.
Re: Mid Length vs Carbine Length Gas System
Posted: Wed Jun 06, 2018 2:31 pm
by The Annoyed Man
Abraham wrote: Wed Jun 06, 2018 12:15 pm
TAM,
I don't know the benefits between between 'carbine vs. mid length'?
For those of us who don't know, will you provide a thumbnail sketch??
Thanks!
jason812 wrote: Wed Jun 06, 2018 12:48 pm
Gas systems lengths from closest to chamber are pistol, carbine, mid-length, and rifle. The farther away from the chamber, the less pressure in the gas tube to cycle the bolt, which means the slower the bolt moves. The slower the bolt moves, the easier it is on parts and recoil. That's the summary.
You can also slow the bolt down with different buffer weights and springs or an adjustable gas block. Generally you want a minimum 4" of barrel length past the gas port.
What jason812 said.
Some people describe the Carbine length gas system as “over-gassing” the gun, causing the bolt to cycle
too fast. In practical terms, it means that the recoil will be perceived as being more abrupt. Not that AR recoil is heavy - it’s not - but it can be made smoother by altering the speed of the bolt. But like Jason said, there are other issues. I’ve never had an AR with a mid or rifle length gas system “short stroke”, where it either failed to pick up the next round, or failed to lock open on the last round. I
have had it happen just a few times over the years on an AR with a carbine length gas system. (Curiously, I’ve never had it happen with a .300 Blk SBR with a pistol length gas system, but i attribute that to the much heavier bullets the gun fires.) Many people are not aware of the fact that there are different weights of buffers available, and that the buffer system can be tuned to improve performance and alter recoil perception. I have two carbine-length AR15s. One has a standard carbine length direct impingement gas system; the other has a mid-length gas piston system. The DI gun gets dirty just like any other carbine, and I did play with buffer weights to eliminate overgassing and short stroking. It is reliable, but it still has sharper recoil than the piston gun has. The gas piston gun has run like a clock from day one, and runs much cleaner. The piston gun also has a much smoother recoil impulse due to (A) proper buffer weight, (B) the added weight of the piston and drive rod in the recoil cycle, and (C) a mid-length gas system.
But really, if you have a 16” carbine and it is running well for you, I wouldn’t fool with it. Changing the length gas system would give you a
slightly smoother recoil impulse, but it isn’t a
dramatic improvement, and it’s not like an AR carbine has World-thumping recoil. Plus, doing so would come at a price. Barrels are expensive, not to mention the ancillary parts like a longer gas tube, etc. The only time I’ve converted an existing AR from one length of gas system to another, I was converting a lot of other things about that gun too. I converted a 16” carbine with a carbine length gas system in an 1:9 chrome-moly M4 profile barrel, to a 18” DMR/SPR with a rifle length gas system in a 1:8 stainless heavy match grade barrel. Originally it was set up to fire 55 grain bullets best. After, it was set up to fire 75-77 grain OTM best.
Re: Mid Length vs Carbine Length Gas System
Posted: Wed Jun 06, 2018 2:31 pm
by The Annoyed Man
Duplicate post deleted.
Re: Mid Length vs Carbine Length Gas System
Posted: Wed Jun 06, 2018 2:37 pm
by Bitter Clinger
The Annoyed Man wrote: Wed Jun 06, 2018 2:31 pm
Abraham wrote: Wed Jun 06, 2018 12:15 pm
TAM,
I don't know the benefits between between 'carbine vs. mid length'?
For those of us who don't know, will you provide a thumbnail sketch??
Thanks!
jason812 wrote: Wed Jun 06, 2018 12:48 pm
Gas systems lengths from closest to chamber are pistol, carbine, mid-length, and rifle. The farther away from the chamber, the less pressure in the gas tube to cycle the bolt, which means the slower the bolt moves. The slower the bolt moves, the easier it is on parts and recoil. That's the summary.
You can also slow the bolt down with different buffer weights and springs or an adjustable gas block. Generally you want a minimum 4" of barrel length past the gas port.
What jason812 said.
Some people describe the Carbine length gas system as “over-gassing” the gun, causing the bolt to cycle
too fast. In practical terms, it means that the recoil will be perceived as being more abrupt. Not that AR recoil is heavy - it’s not - but it can be made smoother by altering the speed of the bolt. But like Jason said, there are other issues. I’ve never had an AR with a mid or rifle length gas system “short stroke”, where it either failed to pick up the next round, or failed to lock open on the last round. I
have had it happen just a few times over the years on an AR with a carbine length gas system. (Curiously, I’ve never had it happen with a .300 Blk SBR with a pistol length gas system, but i attribute that to the much heavier bullets the gun fires.) Many people are not aware of the fact that there are different weights of buffers available, and that the buffer system can be tuned to improve performance and alter recoil perception. I have two carbine-length AR15s. One has a standard carbine length direct impingement gas system; the other has a mid-length gas piston system. The DI gun gets dirty just like any other carbine, and I did play with buffer weights to eliminate overgassing and short stroking. It is reliable, but it still has sharper recoil than the piston gun has. The gas piston gun has run like a clock from day one, and runs much cleaner. The piston gun also has a much smoother recoil impulse due to (A) proper buffer weight, (B) the added weight of the piston and drive rod in the recoil cycle, and (C) a mid-length gas system.
But really, if you have a 16” carbine and it is running well for you, I wouldn’t fool with it. Changing the length gas system would give you a
slightly smoother recoil impulse, but it isn’t a
dramatic improvement, and it’s not like an AR carbine has World-thumping recoil. Plus, doing so would come at a price. Barrels are expensive, not to mention the ancillary parts like a longer gas tube, etc. The only time I’ve converted an existing AR from one length of gas system to another, I was converting a lot of other things about that gun too. I converted a 16” carbine with a carbine length gas system in an 1:9 chrome-moly M4 profile barrel, to a 18” DMR/SPR with a rifle length gas system in a 1:8 stainless heavy match grade barrel. Originally it was set up to fire 55 grain bullets best. After, it was set up to fire 75-77 grain OTM best.
I solved an "over-gassing" problem on a 7.5" bbl AR pistol by simply fitting it with a heavier buffer. Changing to a "pigtail" gas tube (ostensibly to afford some milli-seconds of added dwell time) would have been far more expensive and labor / time consuming, with no guarantee of any better results.
Re: Mid Length vs Carbine Length Gas System
Posted: Wed Jun 06, 2018 2:47 pm
by Abraham
Thanks all.
Now, given my lack of skill in some many things, maybe my wife can explain it me, as she so often does when I wonder why this or that...