Cutting an AR barrel down?

[00BlasterResto]

Is there any advantage of haveing a factory barrel? Or rather is there any disadvantage to buying say, a 16" midlength upper and cutting the barrel down to 10.5? Thinking about an SBR in the future, but wouldn't mind it being 16" for now. Just wondering if there is any issue with cutting down an notched M4 type barrel.

 

[phylodog]

If it is chrome lined you don't want to cut it. If it isn't chrome lined you may have to open up the gas port a touch to maintain reliability as the bullet will have less time in the barrel beyond the gas port to provide the back pressure to cycle the action.

 

[00BlasterResto]

Thank you, Apparently I cannot Rep you now.

 

[jsx1043]

Tagging along - I have this barrel, and am thinking about SBR'ing it:

It's a 10.5' FN bbl with a 5.5" flash hider. The funny part is, that there are no spots for wrench on the FH, and thus I can't tell if it is threaded on, or fitted some other way. I am assuming it is welded and pinned, it doesn't budge.

 

[nipprdog]

I am assuming it is welded and pinned, it doesn't budge.

Yep. That's the law.

If it does budge, don't post it!

 

[indoorsoccerfrea]

Yep. That's the law.

If it does budge, don't post it!

Yes and no. If the barrel is on a gun that is not an SBR, then it does need to be permanently affixed. However, if the gun is a legal SBR, then the barrel can be 1/2 inch if you so desire.

 

[jsx1043]

It's permanently attached right now. What I want to do is remove it and put on a shorter flash hider after I get my stamp in for the lower. I saw a walkthrough at one time that talked about removing permanently attached flash hiders by cutting up the length and grinding down on top of where the threads would be. My questions are:

1. Has anyone done this?
2. Has anyone done something different?
3. Does anyone know of the different attachment methods for permanent flash hiders?

 

[Don]

Not saying that is not a FN barrel, but I HIGHLY doubt it. I have been proven wrong before and will accept it again. They can not make civilian parts. I was lucky enough to snag this up for $135 at the 1500 a while back. Cage code checks out and all. The hard part would be to find out where the pin is on your flash hider, cutting the weld and maybe drilling it out if all is good then your in the clear by just adding a flash hider. if not, it could be removed with a lathe. Places like adco and ar15barrels.com both trim chromed barrels, it don't hurt them.

Is you barrel marked FNMI?

 

[jsx1043]

Well, it looks like from some research, that the upper receiver has a Cerro Forge stamp, and the barrel is unmarked. I bought it FTF and was told it was a FN upper from Tony's Custom Uppers in Ohio.

FWIW - this upper has been A1 and a superb shooter. I'm just looking at the SBR route. I don't know if it would be easier to mod this one or jut get a new one...

 

[Don]

Ole Tony likes to bend the truth sometimes, from what I hear though he makes alot of his own barrels though.

 

[jrm]

If you look on the underside of the flash hider you should be able to see a small spot where a pin was welded on.

It is also possibly held on with high temp solder

 

[Marc]

sell your barrel and use the money to put towards a short barrel.

 

[shooter521]

is there any disadvantage to buying say, a 16" midlength upper and cutting the barrel down to 10.5?

The gas port on a mid-length barrel is exactly 10" from the face of the receiver. If you cut the barrel down to 10.5", you would not have enough material forward of the gas port to install a gas block and a muzzle device, to say nothing of how cycling would be affected.

If you want to go the cut-down-to-10.5 route, you'll want to start with a barrel that has a carbine-length gas system.

 

[jsx1043]

If you look on the underside of the flash hider you should be able to see a small spot where a pin was welded on.

It is also possibly held on with high temp solder

Thanks JRM, that's the kind of info I was looking for.

Does anyone know if there are any other fitting methods for flash hiders that are not threaded on? Does anyone make a barrel with a pushed/pinned FH?