A quick very noob question to precision shooting.  I have not seen this with all the vids on Sniper 101.  Or maybe I missed this segment.

What is the preferred mounting for a scope on a AR10 with 20" barrel?  Cantilevered mount (like a Larue SPR-E) or individual mounting rings?  Why?  Thanks.

Edit:  Please move if this is in the wrong forum.  Thanks again.

cantilevered mount for proper eye relief

It could be both - depending on the optic.  Look....   Everyone has their favorites.  But I've learned a very valuable lesson over the years - at great cost to me on missing shots while hunting.  I will spare no expense on mounts for my optics.  

If going with scopes like a 1-4 or 1-6, (scopes with small objective lens)  I like the LaRue LT-104.  (I just bought one for my VX-6 1-6X24 and love it)

If using an optic with a large objective lens, I tend to like individual rings.  I exclusively use Leupold Mark 4 rings.  They are rock solid, come in both steel and aluminum versions, and they come in varying heights to serve your specific needs.    

Good luck!!

I should have included the scope.  SWFA SS 3 - 15 X 42.  

Evidently, the brand of the mount and rings are also taken into consideration. Is there a price range of obtaining a better mount or ring?

You want the mount/rings to be fully on the receiver, not on the handguard (if you have a top rail on yours), and also to have the scope far enough forward to have enough eye relief to get a good sight picture without craning your neck too much. Usually that means a cantilever mount is required.

Thanks.  I have both cantilever mounts & individual rings.  I would probably re-do my mounting and re-adjust as when I do a cheek weld that there wouldn't be any lens shadows.  At present, I have a QD Cantilever.  I would change to a more semi-permanent mounting.

I went with the GG&G mount.  With a Mk 4 LR/T the eye relief worked out perfectly and it holds zero the best of any QD I've used.

I have the same scope.  Going to mount it today actually when I get to my shop.  I went with the SALT mount they had on sale when I got the scope.  Seems well made but I don't plan on removing it from the rifle.  If you want to do that I would get a throw lever style mount.

I also have the SALT mount.  I would say it is very robust.  I opted for a LaRue LT104.  Starting to get a collection of mounts & rings.

I read a thread some where which I could not locate in reference to MOAs.

If my AR 10 and scope mount has ZERO MOA,  how far would my shots go before I need to upgrade the mounts to get to longer distance in reference to cant?

Scope mounts are sometimes inclined to prevent you from running out of elevation adjustment at long range. The best way to find your max adjustment range is to count the clicks you can dial up from your 100 yard zero before the scope bottoms out. Then compare your available adjustment with the adjustments that your ballistic tables say you need to dial between your 100 yard zero and the actual target distances. Remember in a hot and high environment, you will get longer maximum range than at sea level in the cold.

Try http://www.jbmballistics.com/ to help you generate some approximations of the ballistics tables for your rifle.

That depends on the amount of internal elevation adjustment in your scope, the environmental conditions affecting bullet drop, and the ballistics of your particular load.  With my Rem 700 (20" barreled .308win) with 168gr FGMM (SMK), my SWFA SS 10x42 on a 20moa base gives me 27 mils of adjustment UP, which would  allow me to dial out to 1400yds under common conditions in my area.  Without the 20moa base, I would have about 21 mils of adjustment, which would put me out to around 1200yds.  

You just have to measure the amount of elevation adjustment you have UP (from your zero), then enter your rifle/load/environmental conditions into JBM ballistics to figure out how much adjustment you'll need at various ranges.  The SWFA line of scopes (at least the fixed mag ones) have a TON of elevation adjustment... I didn't really need the 20moa base since I have nowhere to shoot past 1k yards, but I figured it was better to have it and not need it than need it and not have it in the future.