03-17-2016, 12:47 PM
(This post was last modified: 03-17-2016, 06:46 PM by Keep The Change.)
When I started building a long distance gun I had a Vltor MUR to use because I liked the thicker wall and beefed up upper. I had a 24" barrel heavy contour and I checked the fit to the Vltor. There was a lot of play between the upper and barrel extension and the lip of the extension did not sit flush on the upper. So I knew it would need to be lapped. But if I remember correctly there about 0.004" clearance between upper ID and extension OD.
So if you plan on using a forged upper, even a Vltor I would lap it and bed the barrel when you install it.
Because of this fit in the Vltor, I decided to buy a billet upper. I bought a LH side charger (non-reciprocating) made by WMA/Holy City Rifleworks. The upper was square and the fit to extension was much tighter. I've seen uppers so snug that you had to tap the barrel into place. Mine was not that tight, but I would say there was about 0.001-0.002 clearance. I still bedded the barrel on this one too.
I'm saving my Vltor for a carbine Grendel. I cerakoted and lapped the face and it is ready to go.
So if you plan on using a forged upper, even a Vltor I would lap it and bed the barrel when you install it.
Because of this fit in the Vltor, I decided to buy a billet upper. I bought a LH side charger (non-reciprocating) made by WMA/Holy City Rifleworks. The upper was square and the fit to extension was much tighter. I've seen uppers so snug that you had to tap the barrel into place. Mine was not that tight, but I would say there was about 0.001-0.002 clearance. I still bedded the barrel on this one too.
I'm saving my Vltor for a carbine Grendel. I cerakoted and lapped the face and it is ready to go.