Gunsmithing Chrome line barrel cutting? Which method

[FUNCTIONAL]

Have to chop down a few chrome lined AR barrels and have read a few different ways so I figured I'd ask. Searching didnt turn up anything earlier than 2012 and most threads are usually filled with people arguing over if it will flake/peel or not.

I'm not convinced barrel chrome will peel on quality barrels, this isnt decorative chrome (these will be LMT barrels). So unless someone has first hand experience with BARRELS...not decorative chrome lets just focus on method.

From what I've read so far theres 3 ways and only 2 I think are correct.
1) Go at it like a normal SS barrel. Only mention of carbide cutters, will HSS work fine or is the rigidity of carbide needed?

2) Go at it like a normal SS barrel but be sure to have coolant running over it and take very light cuts slowly.

3) Cut it off with a band saw and finish the crown with a grinding tool. I cant imagine this finish would look good or why a single point cutter wouldnt give equal quality finish.

How do you cut the chrome lined barrels?

 

[kortik]

Feels like you want to crown chrome lined barrels. If yes, then watch this video, it may be helpful to answer your question:

 

[Ledzep]

I may be completely wrong but my initial impression is that the chrome lining isn't thick enough to really worry about. Maybe try it out on the sections you cut off first to make sure, but I'd just bring a boring bar from inside to out at whichever angle you prefer (0, 11, 45).

 

[FUNCTIONAL]

I'm cutting them from 14.5" to 10.3" so really my question is for the cut and then crown. Threading from everything I've seen should be just like a SS barrel since the lining is just the bore and slightly penetrating the steel. I will watch that video a bit later but thank you for sending it...if it is information on crowning it should give me most my answers.

 

[Ledzep]

The chrome lining is built up on top of the barrel steel in the bore, and is only a few thousandths thick.

 

[flyer]

I would push a lead ball or bullet through the bore to the muzzle and then cut the crown from the barrel in to the lead. That should avoid any peeling.

Depending on the tooling, it might make sense to grind the chrome off of the existing crown before you crown because it's hardness can make a difficult cut.

Once the crown is cut and you start shooting, hopefully the chrome will maintain it's bond and not begin peeling.

Also, the bare metal may allow a way for rust to form between the base metal and chrome lining so watch out for that.

 

[Terry Cross]

Not even a few thousandths thick.

Pretend it is not there. Cut the barrel. Indicate the bore and finish off the crown at good spindle speed and with sharp tooling. Carbide micro-boring bar if you don't run inserts will work well.

Don't forget to function check every thing after shortening. A lot of 5.56 guns will be super bitchy after changing the port to crown length into the area you are working.

./

 

[FUNCTIONAL]

Not even a few thousandths thick.

Pretend it is not there. Cut the barrel. Indicate the bore and finish off the crown at good spindle speed and with sharp tooling. Carbide micro-boring bar if you don't run inserts will work well.

Don't forget to function check every thing after shortening. A lot of 5.56 guns will be super bitchy after changing the port to crown length into the area you are working.

./

Awesome thanks Terry.

Ill be sticking to the crane cutdown/measurement specs for a mk18 cutdown. 14.5 to 10.3 measured from bolt face locked in the extension and gas port opened up to .070". With so many done to these specs hopefully i dont get an unlucky anomaly haha.

 

[powdahound76]

I was gonna say sawzall and a brass screw........

I seen it once on the internet.......

Always good when @Terry Cross weighs in.

We have a lot of good fortune to learn from what these top tier smiths offer up for free here on the Hide. I have seen many offer up a lot and Mr Cross is very classy about it.
I don't do other shooting forums except a small one to keep in touch with an old friend. Not sure any other places have as much coolness as the Hide in this regard.

 

[FUNCTIONAL]

I was gonna say sawzall and a brass screw........

I seen it once on the internet.......

Always good when @Terry Cross weighs in.

We have a lot of good fortune to learn from what these top tier smiths offer up for free here on the Hide. I have seen many offer up a lot and Mr Cross is very classy about it.
I don't do other shooting forums except a small one to keep in touch with an old friend. Not sure any other places have as much coolness as the Hide in this regard.

Shoot I was gunna break out my dremel with cut off wheel and grinding stone after what i read!

Love the resources here...I just try not to ask unless I have to. Dont want to bug them too much and have them not bother after a while haha!