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Posted: 9/7/2012 4:16:18 PM EDT
| When a gunsmith shortens an AR15 barrel and re-thread, does it happen with the entire rifle or do they actually strip it down to barrel only and do the threading and chopping? |
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I take the barrel off the reciever.
Chuck the barrel up in a 4 jaw chuck. Insert a proper fitting range rod into the bore at the muzzle. Dial indicate off the rod until the BORE is dead true then thread the barrel for the brake, flashider, etc. I am CERTAIN that most folks go to that trouble but hey thats just me. Thats why I get paid the big bucks. 
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I would assume you could do it perfectly fine with the barrel still in the upper receiver. You have to do that with AKs since you'd have to press the barrel out.
And now seeing that you're asking about cutting and re-threading, I don't know how most companies do it. You probably could leave it in the upper for the entire procedure as long as you support the barrel and receiver. The biggest problem would be bending the receiver while using the die to thread the barrel. It can take some muscle to twist the die, so an unsupported barrel would be an issue. |
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It's possible to do it on the rifle. They make a threading kit that consists of the threading die plus a piece called a TAT that is a pilot that fits into the bore so as to guide the die on straight.
I did my naked-barrel FAL, and it wasn't too hard. Toughest part was filing the OD of the barrel down to the correct diameter to take the threads. I believe you can buy the kits from Brownells, then source the die handle locally or over the 'net. |
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Ok, sounds good. However it wasn't in my intention to do this my self. I was going to send it to a gun smith. But you know its weekend now, so I could as well do some research before meeting up with the gun smith on monday. (Gun smiths does not have much experience on AR15 platforms in my country, so I need to find out some info my self)
Anotherthing I bumped into here at ar15.com was another user who chopped down his barrel and the project end up with 20 clicks to the left on his rear sight. Now is this chopping of ar15 barrel a risky affair? Is it like 50/50 for a perfect result? PS: I have thought about the dwell time and gas port location/distance when going 16.5" down to 14.5", but maybe there are some more things to know before cutting?? I got a carbine gas length on my piston gun. I've been told, the 14.5 will actually run smoother and more gentle to the parts than the 16.5 when I have a carbine gas length. Is this true? |
600 Good to see a Dane here. 
Anotherthing I bumped into here at ar15.com was another user who chopped down his barrel and the project end up with 20 clicks to the left on his rear sight. Now is this chopping of ar15 barrel a risky affair? Is it like 50/50 for a perfect result?
I have seen this happen from time to time in my 35+ years of Gunsmithing. It occurs when two conditions are present. The BORE is not concentric with the outside diameter of the barrel and the bore is not absolutley straight. Lets say that you sight your 24" barrel in then you cut it down to a shorter length. If the conditions mentioned above are present in that barrel you will have problems. The bore of that barrel is now say .030 off center at 3:00,11:00 7:00 or whatever it happens to be. all oyur previous sightin dope is now usless. That is why I have always & will always continue to buy the best quality barrel that I can. That means Lothar Walther, Kreiger, Lilja and Rock Creek which is cut rifled. |
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Hmm...that makes me wonder the maker behind SIG516 rifles (German made version)? Anyone know?
Anyway, so if the barrel is of high quality such as Lothar Walther etc. then this problem should not occur right? Then the bore is concentric and so is the outer diamter of the barrel. Is this correctly understood? |
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Quoted:
Hmm...that makes me wonder the maker behind SIG516 rifles (German made version)? Anyone know? Anyway, so if the barrel is of high quality such as Lothar Walther etc. then this problem should not occur right? Then the bore is concentric and so is the outer diamter of the barrel. Is this correctly understood? 600 you are correct. I have been useing Lothar Walther barrels almost exclusivly for the last 10 years or so & never had problems with non-concentricity. |
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Ok, I think I got enough information to carry this on.
Last to know is rust. I don't know what kind of barrel my AR15 got, but once the cutting and re-threading has been done, do I have to worry about rust in the threading? There will be a compensator installed on it, do I have to worry about rust attacking the un-protected thread beneath the compensator/flash hider? |
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I took the rifle to the gunsmith and he told me it was very risky to cut down barrel on AR15, because of that .223/5.56 round. I could risk ruin my accuracy by doing it.
I came back home and did some research and found out that people talked about it various places. And the major concern is in chromed line vs. non-chrome lined barrels. Those who had their chromelined, they risk of accuracy problem, because of the chrome flaking off and those without the chrome line, should not worry. What is your thought people? My rifle is not chrome lined but hammerforged. Would a barrel cutting effect accuracy or not for the 223/556 round? Damn confused! 
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Quoted: I took the rifle to the gunsmith and he told me it was very risky to cut down barrel on AR15, because of that .223/5.56 round. I could risk ruin my accuracy by doing it. he is an idiot, the cl thing has been destroyed as well it must suck not having a dutch adco |
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