Gunsmithing would it work (cutting back AR barrel)

[Captain Moroni]

OK I have a bushmaster varminter that I would like to cut the barrel down on its not the stainless so it has flutes my questions are would there be enough metal left to thread 1/2x28 if I turned it down to remove the flutes? and also would it reliablely cycle with the muzzle roughly 3" from the gas tube? Any help or info would be great
Thanks Tucker

yes just rebarreling is an option I would just like to know if this could be done

 

[dmg308]

Re: would it work (cutting back AR barrel)

Not a good idea it should be chrome lined and the does not lend itself to being cut down.Were it is cut down the chrome will be prone to flakeing.Get the barrel you want switch it out and sell the other.

 

[Captain Moroni]

Re: would it work (cutting back AR barrel)

dmg, the varminter bbl is not chromed so with that out of the way would there be any other hang ups?
Thanks Tucker

 

[Brain]

Re: would it work (cutting back AR barrel)

Rifle length gas tube with only 3" of barrel in front of the port? I predict cycling issues.

 

[oneshot onekill]

Re: would it work (cutting back AR barrel)

I wouldn't think cycling would be an issue. The amount of gas going into the port and cycling the action shouldn't be reduced just because it's only 3" from the end of the bore. The bullet passes the port first!

 

[Brain]

Re: would it work (cutting back AR barrel)

The volume as well as the duration of gas entering the tube will in fact be reduced. Yes, the bullet passes the gas port first, but the time after which that the bullet continues to seal the bore before exiting the muzzle will not allow enough time for the necessary gas impulse to cycle the bolt completely and/or reliably.

Were this not an issue, there would be no reason to shorten the gas system on carbines which would allow a longer and more effective sight radius. Case in point is the bushmaster dissipator. The gas block on the dissipator is not part of the sight base but rather a carbine length system under the rifle length handguard. This allows proper function in a carbine while maintaining the longer sight radius of a 20" rifle.

 

[dmg308]

Re: would it work (cutting back AR barrel)

They can over come that by changing the port diameter.It is pretty common now to run an 18" spr barrel with a rifle length gas tube.
If it is indeed not chrome lined it will work out though probably not cost effective.

 

[Captain Moroni]

Re: would it work (cutting back AR barrel)

who has the best prices/quality on barrels?

 

[scotharr]

Re: would it work (cutting back AR barrel)

As mentioned by others, the distance after the gas port is part of the gas system engineering, "dwell time" is what they call it. I personally would not change the barrel length, especially since you are also talking about re-contouring it. Just get a new barrel.

I think the varminter has a 24" barrel. Why not get a 20" barrel? That is THE length for a rifle-length system. You should have many barrel/contour choices in that length.

 

[oneshot onekill]

Re: would it work (cutting back AR barrel)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brain</div><div class="ubbcode-body">The volume as well as the duration of gas entering the tube will in fact be reduced. Yes, the bullet passes the gas port first, but the time after which that the bullet continues to seal the bore before exiting the muzzle will not allow enough time for the necessary gas impulse to cycle the bolt completely and/or reliably.

Were this not an issue, there would be no reason to shorten the gas system on carbines which would allow a longer and more effective sight radius. Case in point is the bushmaster dissipator. The gas block on the dissipator is not part of the sight base but rather a carbine length system under the rifle length handguard. This allows proper function in a carbine while maintaining the longer sight radius of a 20" rifle.</div></div> Thanks for the education! I wasn't aware of the importance of the duration. Makes sense though... when I really wrap my brain around it