This is going on a Colt 6920 Magpul edition with the BUIS. I have decided on a Weaver GS 3-10x40.

Thanks

Budget? Most mounts will work - you may see a slight blur from the FSB at 3x but it will go away at any magnification above that. I believe those are 1'' tubes

No budget, whatever is the best. I have seen single mount, double mount, and QR mount. I would like to do a quick release mount but that is not necessary. I just need something that will put the scope in the right position.

Return to zero QD mounts (not necessarily in any order than my personal preference):

1.  Larue 1.5 SPR, Model LT-104.

2.  ADM Recon.

Fixed cantilever mount:

1.  Aero Precision Ultralight

2.  Leupold Mark 2 IMS


Two piece mounts - separate rings:

None on an AR15.   Any good tactical mounts on the longer receiver of AR10 type rifles.  

Your 6920 has the short AR15 receiver.  Some people use the inexpensive Nikon P mounts and seem not to have any problems.  I think they are of marginal build quality, but would probably get you by.

Others might use an extended 1/2" riser with low or medium tactical rings.  That ends up being as expensive as the fixed cantilever mounts, if not moreso, and have the disadvantage of possibly interfering with use of backup sights and adding more weight and bulk.   I would use them only if you have an unusual cheek weld and need a lower than typical scope mounting position.

Were I you, I'd put the GST in Larue LT-104 and be done.   While the Aero Precision ultralight is lighter by three or four ounces than the others, I still think that the Mark 2 IMS is a more solidly made mount if you want to go with a fixed mount and not trying to build an untralight rifle.

Others here will advocate for Bobro or other options.  I'm not saying they are right or wrong.  I'm just reporting what I know works from my own present or past experience.

The Warne XSKEL "gen 2" is a damn good mount.

The new version is light and has an extended cantilever.  Although not a true quick release, it is a return-to-zero mount.

I like the fact that it positions the scope slightly lower than most other AR specific mounts.

Thanks for the advice. I went with the Leupold since after thinking about it I have no real need for a QR mount.