short AR barrel on a car gas system

It's a bit more than that.

The port pressure differs a lot on barrels in this lenght than ones much further from the gas port.

Short Barrel guns are much more sensitive than longer guns.

You can get a very reliable short gun - by opening the gas port up - but you need to counter it with a heavy buffer and spring.
However you will suffer bolt life


The best system for each barrel is one that is tuned for the loading you will use.
Working the required port pressure.

I've seen guns setup for suppressor use with smaller gas ports that don't lock back the action when not used with a suppressor (gas port a wee bit too small - but that is what the user wanted).

Ideally you want the least gas pressure going back to reliably cycle the gun, that keeps the action cleaner, and longer part life.

11.5 is the better barrel of the above lengths to do that in.



Secondly for those using the weapon against other people, the additional barrel length will give added velocity - adding in fragmentation, and range.

That said, everything is a compromise as you want the short barrel for a reason (other than cool points).
 
Quite true

KevinB said:
It's a bit more than that.

The port pressure differs a lot on barrels in this lenght than ones much further from the gas port.

Short Barrel guns are much more sensitive than longer guns.

You can get a very reliable short gun - by opening the gas port up - but you need to counter it with a heavy buffer and spring.
However you will suffer bolt life


The best system for each barrel is one that is tuned for the loading you will use.
Working the required port pressure.

I've seen guns setup for suppressor use with smaller gas ports that don't lock back the action when not used with a suppressor (gas port a wee bit too small - but that is what the user wanted).

Ideally you want the least gas pressure going back to reliably cycle the gun, that keeps the action cleaner, and longer part life.

11.5 is the better barrel of the above lengths to do that in.



Secondly for those using the weapon against other people, the additional barrel length will give added velocity - adding in fragmentation, and range.

That said, everything is a compromise as you want the short barrel for a reason (other than cool points).
Click to expand...

1 1/2 " difference is meaningless that short once you go below 14 " After 14 unburnt powder is allways a problem - as well as short stroking with civilian ammo - short stroking in cold weather - short stroking with dry gun etc.
 
I beg to differ.

There are ammuntions and powders designed specifically for short guns (10.3-11.5)

Look at both high speed video from those barrel lengths, as well as port pressure, and velocity...
 
FYI I have no problems with the current crop of Colt 10.3 Mk18 barrles or the JSOC LMT 10.5 They have had enough R&D into them to ensure that the systems function.

However I think from personal experience that the 11.5 barrel is a better length - for very minimal increase on OAL, you gain a fair bit of powder burn for normal rounds.

*I dont work with civilian ammuntion, thus everything I talk about is based off either M855, or the Blackhills loadings of Mk262, AA40 and AA17 BrownTip.

Many Short Barrel users went to the PIP RRLP Optimized BrownTip loading

My personal warm fuzzy from a 11.5 is you can use a Grenade launcher and a suppressor ;)
 
I am ambivolent on the 12.5"

I don't think its bad - I just view short guns as a niche item, and when you get into 12.5 you still need speciality ammo, and whether the 14.5 is just as good for OAL ish for a more generalized role?

Very few units want to go to 12.5 - even the 1" OAL increase from the 11.5" seems to draw major drama.

Midlength gas does not really work in a 12.5, that seems to be the 13.7" arena and greater. So with the 12.5 you still run a low life span bolt.

If 12.5 had been the original shorty design it likley would have gotten a great deal more acceptance than it gets, the majority of 12.5" guns I have seen are 7.62 (which is whole seperate issue :bangHead: as to why you want 30-30 ballistics in a 7.62NATO package)
 
KevinB said:
I beg to differ.

There are ammuntions and powders designed specifically for short guns (10.3-11.5)

Look at both high speed video from those barrel lengths, as well as port pressure, and velocity...
Click to expand...

Yes absolutely - but who makes ammo like that ? except reloaders --
In Kanada there are no purchasable loaded rounds for shorties except from reloaders if you specify the load-
 
esquif said:
11.5 is as short as you can go and still be usefull
Click to expand...

I to have reservations about going below the 11.5" mark. I have shot out too 500m with my 11.5" (works great by the way) it also sports a KFS (which may or may not help), the rounds grouped good enough for the deliberate service rifle match on a 4x4 target to score, but the rounds went sub-sonic.
 
a 10" barrel is purely a CQB barrel, outside the room it is useless for anything more than paper. Remember just because you hear the round hit a steel target at 300 doesn't mean the down range ballistics are doing what they should be. FP you are right, there are lots of people out there looking cool, this is the downside of hollywood!!!!
 
Kevin,

What do you think of the longevity of the Colt Canada CQB gun? How many K should one expect from the weapon before bolt or other parts failure?

How would this compare to the longevity of the USN MK 18 guns? VS Standard M4's?

Thanks,

Rich
 
Rich,

My baseline for 10ish inch guns with conventional bolt styles is a 3-5k bolt life - depending upon firing schedule and suppressor usage.

They may last longer - but I would replace at 5k if it does.

Diemaco/Colt Canada CHF barrels are oneof the best barrels on the market for life and accuracy. I would estimate that a 15-20k life span would not be unusual -- gas port errosion may be an issue - and could require going to a heavier buffer sometime in that timeline (as well as maintenance replace of springs etc.)
 
You must log in or register to reply here.
Back
Top Bottom