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View Full Version : Cutting 20" inch barrel to 16" for AR15


siznarf
07-01-2012, 10:16 PM
I have a White Oak 20" SDM barrel 1:8 that I am thinking about selling and replacing it with a good quality 16"

I like this barrel a lot and really appreciate how accurate it is. I'm not too sure that a 16" barrel would be as accurate as this one that is why I am hesitant in selling it.

A friend of mine suggested that I look into having the barrel professional cut down to 16" ... now the question is, will the barrel retain the same accuracy? Also, what possible gains/losses am I going to expect?

This is all very new to me and I look to you guys for help/ideas ..


Thanks!!

winnre
07-01-2012, 10:23 PM
Buy a 16" upper and have two.

killathrilla
07-01-2012, 10:26 PM
^this +1

siznarf
07-01-2012, 10:28 PM
Buy a 16" upper and have two.

Just need the barrel ... I have all the other components. What barrel would you recommend to compare with the WOA?

pyro3k2
07-01-2012, 10:37 PM
please for the love of Kalashnikov and all that is holy DO NOT cut that barrel. Just buy another barrel and replace the current one. I'm sure selling a top quality barrel like that will leave you enough money to buy another barrel and have some extra money left over.

USM0083
07-01-2012, 10:41 PM
Done properly it should just as accurate. It might even be a little more accurate.

However, it you would have to open up the gas port. The best I can explain is that there is a relationship between gas port size, gas port location, barrel length, and amount of barrel in front of the gas port.

Dwell time is the time from when the bullet passes the gas port and before it exits the barrel. Insufficient dwell time and the rifle won't cycle properly, as there is not enough gas to cycle the action.

A 16" barrel with a rifle length gas system can be made to function, but it is not an ideal setup.

I had a 20" cut to 18.5" with no change in gas port size, and it ran fine, though I sold it.

siznarf
07-01-2012, 10:48 PM
please for the love of Kalashnikov and all that is holy DO NOT cut that barrel. Just buy another barrel and replace the current one. I'm sure selling a top quality barrel like that will leave you enough money to buy another barrel and have some extra money left over.

lol @ the first sentence.

Yes, buying another barrel definitely is the easy answer here. The question is, will the new 16" be just as accurate as the WOA ~ 300 yards? And, IF the WOA is cut, will it be just as accurate as another quality 16"?

Also, I find it real hard to let the WOA go ... :(

Omega13device
07-01-2012, 10:50 PM
Cutting a 20" barrel down to 16" is not a good idea. As others have noted, it'll turn into an experiment in gas port sizes and will be more trouble than it's worth. Just get a good-quality 16" barrel (or complete upper) and you'll be much happier.

Btw a longer barrel doesn't give you more accuracy (well, precision actually). In fact a shorter barrel may group better, all other things being equal.

siznarf
07-01-2012, 10:56 PM
Done properly it should just as accurate. It might even be a little more accurate.

However, it you would have to open up the gas port. The best I can explain is that there is a relationship between gas port size, gas port location, barrel length, and amount of barrel in front of the gas port.

Dwell time is the time from when the bullet passes the gas port and before it exits the barrel. Insufficient dwell time and the rifle won't cycle properly, as there is not enough gas to cycle the action.

A 16" barrel with a rifle length gas system can be made to function, but it is not an ideal setup.

I had a 20" cut to 18.5" with no change in gas port size, and it ran fine, though I sold it.

Very good info ... I didn't see that coming. I'm almost certain that it is a rifle length gas system but hoping that it's not. 16" might be too short of a cut ... maybe 17-18.5" would work.

Any idea who does this kind of work?

USM0083
07-01-2012, 11:11 PM
Randall at AR15Barrels did all my work (reprofile and chop jobs). http://www.ar15barrels.com/

He still does barrel work, but not much more than that, and I've never had any problems with him or his work, but some have.

Another company is Adco. http://www.adcofirearms.com/shopservices/

SocomM4
07-01-2012, 11:39 PM
Just get a whole new upper. Cutting and crowning the current barrel, plus the gas port tuning is gonna cost you probably as much as a new CHF barrel. You can pick up a PSA CHF barreled upper receiver for 300ish. Cutting the barrel on such a modular weapon is kinda derpy. IMO

winnre
07-02-2012, 8:39 AM
Put up an ad saying you have a 20" upper and will trade for a 16" upper.

HK Dave
07-02-2012, 8:50 AM
WOA, Krieger, Rainier Ultramatch, Shilen... there are so many great ar15 barrel makers, it's hard to go wrong.

And while I have no clue as to how great a shot you are, i'm pretty certain you'd have a hard time being better than one of their barrels.

Nowadays, barrels are so accurate that the majority of the time, the deciding factor becomes the shooter... and contrary to what people "believe" they can do, and what people "say they can do on the internet"... most shooters can't really "do".

BillyGoatMachine
07-02-2012, 9:00 AM
As far as your accuracy question, remember this. A longer barrel will generate more velocity up to a point. With a shorter barrel, theoretically, your will have better accuracy but loss in velocity. A longer barrel has more harmonics while shorter barrels flex less. So there will be no loss in accuracy if you cut it down. It might even shoot better, but I highly doubt you will be able to tell the difference.

Arnelcheeze
07-02-2012, 10:10 AM
do not cut the barrel, you will have gas cycling problems if you do.
buy a new one, sell the old. Fulton Armory has some good match grade barrels at a great price made by Criterion (Krieger)

donw
07-02-2012, 11:50 AM
generally speaking...shorter barrels are not any less, or more, accurate than longer barrels. barrel length can affect velocities, though. (although, there is credence about longer barrels being more accurate at extreme ranges and most precision, LONG range sniper rifles, do have longer barrels)

with top dollar optics, a short barrel rifle could be just as accurate but not as far due too the velocity factor...a 16 year old girl shot a 4" group at 1000 yds with an AR15 recently...that's pretty good when you think about it.

generally speaking, shorter barrels are more for ease and convenience of handling in closer applications...

in the end...it's the shooter that makes the difference.

i hope i'm making sense...:yes::seeya:

siznarf
07-02-2012, 12:12 PM
with top dollar optics, a short barrel rifle could be just as accurate but not as far due too the velocity factor...a 16 year old girl shot a 4" group at 1000 yds with an AR15 recently...that's pretty good when you think about it

What kind setup did she have?

siznarf
07-02-2012, 12:24 PM
Thanks for all the input, it's very much appreciated!

So, having read all the responses, it seems like the potential risks of cutting it outweigh any "pros" that could come out of it. While this is what I had assumed in the beginning, I'm no expert so I had to ask.

With that out of the way, maybe it's time for me to revise my ad and consider selling/trading the whole upper. I like the way a recce setup looks, I might build it like that. Any suggestions on quality barrels?

FatalKitty
07-02-2012, 12:26 PM
www.calguns.net/calgunforum/showthread.php?t=493277

opening up the gas port is NO WHERE NEAR the trouble that some of these responses are making it out to be