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View Full Version : INTERESTING MYSTERY BARREL OR LARGE PAPERWEIGHT?


4895SHOOTER
January 12, 2009, 14:50
Just made an impulse barrel buy: 16" including the AUG style brazed FH. You can view my possible disaster here: http://www.ar15.com/forums/topic.html?b=7&f=47&t=626701 . Is this too short to reliably function? Anyone seen one of these mods before or have any idea as to it's origin?

tac-40
January 13, 2009, 12:03
I shortened the barrel of my G1 to 16.25 inches so I could build a 3 gun match rifle. I had to open up the gas port to almost .125 inches for it to reliably work. I also run a fish gill type brake on the end which I am sure adds to the back pressure to allow for better cycling. So all in all I would say that it is doable, but will need a lot of fine tuning.

Other will be along that have built short barrels and short gas system FAL's to add to you knowledge.

ActionYobbo
January 13, 2009, 13:24
thats about the 4th time I have seen that barrel change hands. funny its always on arf that I have seen it.

4895SHOOTER
January 13, 2009, 14:42
Thanks for the quick replies! As a new member, I am constantly amazed at the priceless help that is available here so I figured I'd give this one a try - it's a very small world. I received the barrel yesterday and am in the process of giving it a good cleaning (initially Butch's now soaking in Hoppes copper solvent which I find is gentle if you can wait between applications) .The bore looks good or "very good" depending on the viewer; crown is excellent as well as the exterior park. I have not gauged the port to see if any opening has been attempted previously - I'll post it later. It's timing appproximately ten o'clock on a new DSA receiver hand fit so I am encouraged. Thanks again!!!

4895SHOOTER
January 13, 2009, 21:01
I removed the front sight and the port gauges approximately 0.135". This should be a bullet eating fouler, but seems to be consistent with the .125" figure mentioned previously with respect to the shorter length/reliability issue. Seems to me that an enterprising person could come up with an exponential graph such as barrel lenghth v.s. barrel port diameter. I guess what I'm looking for is "it might work" or a "don't even try it; get a new barrel" response.

Frenchkat
January 13, 2009, 21:30
The muzzle device looks like a cut down Belgian or Imbel combo device.

bykerhd
January 13, 2009, 22:21
That's a MIGHTY big gas port. :uhoh:
But, if it functions and the bullets go where they are supposed to, the barrel should be fine.
Put it together and try it !

richbug
January 14, 2009, 06:26
Originally posted by ActionYobbo
thats about the 4th time I have seen that barrel change hands. funny its always on arf that I have seen it.

With that port size, and the above info I suspect you bought someone else's problem that has been passed around like a hot potato.

I have been wrong before.

4895SHOOTER
January 14, 2009, 09:19
Thanks again for the replies! What then would be the shortest length to barrel port size which would function 99%; not strip buulets or create excessive fouling? I see the 17"+ figure mentioned in a lot of places, but see DSA selling (and backing with a lifetime warranty) a 16" carbine w/standard length gas system. I don't like the idea of a short gas system because of the pressure curve issues - sort of my barrel issues in reverse. I don't mind making a novice mistake if I can learn a lesson from it - just don't want to repeat it - This thread may prevent someone else from doing the same (I like where this is going).

tac-40
January 15, 2009, 11:41
The Para models came with a 17+" barrel amd standard gas system. A tight gas system would allow you to go down to 16" but you may have to play with the porting a little.

I would go ahead and try out that barrel that you bought. It might work and you'll be happy with everything but the bark.:smile: Luckily, swapping out barrels isn't too much work if you have RATAS' barrel vise and receiver wrench. Replacement barrels are still available out there for a decent price.

4895SHOOTER
January 15, 2009, 12:29
Thanks for the encouragement. I'd feel a lot better if the port had not beeen bored out already, however I'm going to check out the right tools for future swap as you suggested - the locking shoulder is the only other cost. Seems like a nused barrel + $100-$125 for cutting, crowning and threading may be otherwise well spent on the new item from DSA. Thanks again for patiently keeping up with me!

4895SHOOTER
January 20, 2009, 23:07
Thanks!!! You're a mindreader. This is what I was looking for. You have answered my what if questions, and I had thought I was finished if the port was too large. I'm still waiting on some parts from DSA, and possible kit for some small stuff to avoid the temptation of swapping from another complete project. Thanks again.

JAB75
January 21, 2009, 23:10
Twist it up and give it a try. Brass may launch into the next county, but it shouldn't effect function. AKs are over gassed to the extreme, so an FAL carbine with a .135 gas port will be fine.

The real question is: was the barrel line bored properly after being cut down to size?

Gunplumber and ggiilliiee should be along shortly to help answer that.

:biggrin:

-JAB75

4895SHOOTER
January 22, 2009, 00:09
Thanks, I have worked at a public range as a range officer and have witnessed the AK/SKS ejecting brass at least 20 yards in front of the bench on several occasions. The adjustable gas system is at the top of the list of my reasons for using the FAL "style" rifle. I guess I'll cross that bridge when I get to it - I'm concerned about bullet stripping and fouling. I can prep some very light loads with faster powder, and work up to see how it's cycling. I hope to start the project in a few weeks (last word from DSA was they were shipping orders from late Nov.) - thanks again!