I have a 20" Colt HBAR. It shoots excellent. I am thinking of having ADCO cut and rethread at 18". Exactly 2" less barrel would take the HBAR stamping off of the barrel and leave the other markings intact. The 20" is just too long and heavy of a package to me. I know 2" in length isn't going to make a world of difference, but I like the concept of it being slightly shorter and lighter. I have noticed that some 18" barrels have the gas port at mid length and others have it at rifle length. Do the barrels that have the port at rifle length have a standard size gas port or is it different than what would be on my 20"? In the future, I would like to get a can and the length would be more of an issue then. Also, I already have this barrel and the cost of a new 18" 1/7 chrome lined barrel is more than I want to invest to be 2" shorter. Has anyone here done this and did you have to modify the gas port?

If anyone from ADCO is reading this, about what would be the approximate cost ?

Should be $65 ADCO

This

If you send it to ADCO to be cut you just as well have them turn it down and lighten it up too.

Cut, Thread, Reprofile and Repark all in one shot. 65+65= 130 for a rilfe that will handle like a dream compared to an H-bar.

I'll second this.  Have them reprofile the barrel to a light-weight and it will handle beautifully.  

I had a 20" gov't barrel profile and sold it; it was nice shooting, but a little heavy. Sold it, and bought a Noveske 18" barrel instead. So much nicer and lighter

I think that you might have some issues...less distances between the muzzle and gas port will affect dwell time.

It will work fine. A regular SPR is 18in with rifle gas system.

ADCO even cuts 20in uppers to 16in and they still use the rifle gas system but they do open up the gas port.

My bro(member jonnyvain) talked to steve at adco and ended up getting his 20" hbar taken down to a hbar 17.5".  It handles a lot nicer.  Weight isnt cut as much as the balance was improved.

Gentlemen,
Thank you for the input. $65? That's refreshing. I think I will keep the heavy profile and just have ADCO cut it down and thread. I really just wanted to lose some length and make it a little handier. The gas port mics to about .100 . I dont see it needing to be opened up. Thank you all.

Hmm.... it was adco who told me that there could be some issues with an 18"barrel/rifle gas.  I do kinda remember it being a cold weather issue though...a bigger issue up here in MI.

Since you are in Florida you may want to consider Ballistic Advantage also. I recently had some barrel work done by them and the work was top notch. I received the barrel back from them about a week after I shipped it. Check the 'shop services' link for pricing on the barrel cut down and re-threading.