Hi all...  Installed a Cmore quadrail last night, now I'm having problems with grouping.  Shooting at about 50 yards I'm getting 2-3 inch groups with scope.  SO, any suggestions would help.  First, it looks like the front sight is touching the front of the float tube.  I'm thinking this is a bad thing, but I ran out of threads on the barrel nut to turn the float tube in anymore.  So, of course I can put a low profile gas block on and solve that.  Also, I have a scope base mounted between the quad rail and the flat top to get better eye relief, so I'll try moving the base back off the quadrail, however it's extremely solid so I didn't think that would cause a problem.  Any thoughts anyone?  Thanks

Sounds like you're on the right track. I wouldn't trust the scope mounted across the two. I've heard from friends with the C-more that they had problems keeping then tight.

The front sight should not be touching the tube.  What ft/lbs. did you tighten the barrel nut to?  You may have excessive headspace issues.  The C-more is a pretty rigid system, but mounting the front ring of your optic setup is now a good idea either.  If the tube rail is out of alignment with the receiver ever so slightly the optics will be affected adversely.  Any upward pressure on the tube can affect the rise of the ring.

You could also take the tube to a short run machinist and get the front end turned down a little.

(It would cost a lot less than a new folding front sight).

Or dremel it for free. (I had a problem with my SIR [it touched the front handguard cap and I was able to dremel modifiy it in a non-visible area and correct the problem] I didn't realize the problem till I went to the range either.

Thanks guys...torqued more than 35, less than 80 as the instructions for the HG said.  Yeah, I suppose I could dremel it I hadn't thought about that.  As for the optic setup, that maybe a problem that I'll have to solve with a scout rail.  Headspace...I hadn't thought about that since I haven't changed bolts or barrel.  I'll have to get some gauges and check it.  Thanks all.