DPMS offers to cryo treat you barrell for like 60 bucks. suposed to make it more accurate. has any one done this. any one know for a fact that it works. dose it f*** up the chrome?

www.shooterstore.com/acb/showprod.cfm?&DID=90&ObjectGroup_ID=1263&CATID=494

i wouldnt do it to a chrome barrel,but not for fear of messing it up. a chrome barrel isnt as inherently accurate to begin with so its kind of like trying to make a polo pony pull the ox cart. most match barrels will show some improvement with this process. and i think most match rifle makers do cryo their barrels after final machine work on them..pat

Does anybody know the exact proceedure for doing this? I have a unique job that allows me to have thousands (yes thousands) of gallons of this stuff at my disposal. I've always wanted to try it on a few of my AR's, but didn't know the proceedure. Please email direct if possible, or post if not!

Thanks!
Chopperdave

(cut rifling) Kreiger does it.  Lilja (button rifle) doesn't.  Kevin Thomas from Sierra says that Moly is bunk too.... and Sierra sells Moly bullets!  [:)]

Chopperdave: I assume you are talking about liquid nitrogen and you are thinking of dunking your AR barrels in it. If you do may be creating a dangerous situation. I am only putting two and two together here but for the following reasons I'd advise aagainst screwing around with it.

I heard of a small engine manufacturer that decided to cryo treat its connecting rods. They blithely dunked these rods and guess what happened. They started to fail at a much higher rate than before. It turns out that when you change the temperature of a metal rapidly, due to thermal contraction/expansion you are changing the size of the outer layers of the metal in relation to the inner areas of the entire mass of metal, first shrinking when you dunk it, then expanding when it is exposed to room temperature again. This creates microscopic stress fractures which weaken the metal and create points of failure. In an engine, you get a broken con rod. In a rifle, I think you'd you get a kaboom. A big one.

True cryo treatment is a careful process of changing the temperature at a very slow rate to give the metal parts plenty of time to transfer heat energy out and back in so all areas of the metal mass remain at the smallest temperature variance possible. I believe the rate of change is somewhere around a degree an hour, give or take. IIRC, it takes days just to cool the part down, then keep it cold while the cold does its magic to the crystal sructure of the metal, then again slowly warm it.

I'd be careful.