I currently have a BM 16" M4 barrel and I'm thinking about having the barrel reduced to 14.5 and then installing a Phantom flash hider. I've got a good local AR gunsmith and was curious as to how in-depth of a project is this, how much cost would you say is reasonable, and what are the cons if any to actually doing this procedure besides the obvious velocity changes due to the barrel lenghts?

Its more trouble than it could ever be worth. You also need special tools to square and lap the muzzle. if you don't it will shoot around corners. I would not try this one because you may also have to enlarge the gasport so that you get enough pulse to rack the action.I've shortened AK's and SKS's and you have to on those.You need letter, number and fractional bits to do this, and go one size at a time. ($300 drill bit set).Barrels are cheap and easy to install.

Thats true. I got the cutters and pilots from Brownell's in .30 and they really chatter on the SKS chrome bores. But nobody ever bragged about accuracy with them.I could hit a refrigerator at 150 yds 50 % of the time. AR is 100%.

I will repeat the warning about cutting down a chrome linned barrel...  Once you cut the barrel, the chrome may seperate and begin to peel.  Once it starts, there is nothing you can do to stop the process....

I had a 16-inch Bushmaster barrel that I wanted to cut down to 24-inches...  I found it cheaper to sell the barrel and replace it then to cut... plus there was no fear of ending up with a lousy shooter!

A good gunsmith can do this, but it will be a little more expensive.  When properly applied the chrome should not peel.  After it is cut it can then be ground to finish.  Quarterbore knows what he is talking about though.  There are gunsmiths, and then there are gunsmiths.  But look at it this way.  And I quote Quarterbore.  "I had a 16-inch Bushmaster barrel that I wanted to cut down to 24 inch..."  Just imagine with this scenario how many chances the gunsmith will have to get it right.

Quoted: And I quote Quarterbore.  "I had a 16-inch Bushmaster barrel that I wanted to cut down to 24 inch..."  Just imagine with this scenario how many chances the gunsmith will have to get it right.

LOL....  yea, that would take quite a gunsmith, huh?  I meant to say I had a 26-inch upper that I wanted cut down....

WISE ASS!

I know!  I'm starting to feel like one of the guys now.  What was your intented use for that upper?  

To be honest I origianally bought it for parts as I was going to use the receiver to build up a M4A3 carbine upper.  The Barrel had an AK break pinned on it so I was going to cut it down to 24-inches, have the barrel threaded, and make a straight pull bolt action upper using a DPMS Hi-Rise upper.

The reason, here in PA I can't hunt with a semi auto, but by removing the gas system and turning her into a bolt action I could use her to hunt varmints.

As it ended up, I sold the upper on this board and never did end up building a bolt action upper as I bought a good Bolt Action Rem 700 for less money!  The deciding factor was the stories that I had heard at that time about guys having accuracy problems after cutting a chrome linned barrel!