hi i just got a colt ar15 w/ the detachable carry handle and want to put a scope on it. I think i found a mount but i'm not sure of what kind of scope rings i need, i think this mount has dovetail style but i'm not sure.
if you have any other suggestions of a different kind of base that would be great
im going to get a leupold rifleman scope 4x12 40mm scope, it has a 1" tube diameter
A long scope like that needs to be mounted well forward to leave you sufficient eye relief, especially in prone. I use an extended riser (1/2" high) made by Accuracy Speaks (available direct or from Brownell's) combined with standard-height rings. There are now a similar ones available from several sources. This gives me an extra 4" of rail and lets me mount a Leupold 6.5-20x50 LRT (a rather long scope) and gives me the option for an extra 15' of built-in elevation for long range work.
I'm using Burris Signature Zee rings - they are inexpensive and work well, even though they don't have the macho look many seem to like. They use a floating plastic bushing to minimize stress on the scope tube and simplify installation, and offset bushings are available. Bushings with a 0.010" offset are included with 30 mm rings, and 0.010", 0.020" and 0.030" bushings can be purchased for 1" rings. They're inexpensive and work very well. I use them on my spacegun to mount a VX-III 6.5-20x50 LRT and have never had a problem with them.
Also remember that your windage range is restricted when you are at maximum or minimum internal elevation. You can't apply maximum elevation and windage simultaneously due to the round scope tube. You won't need large amounts of windage at 100 yards, but you could need 20+ minutes at 1000 on a windy day. There are minor optical distortions that may be more apparent off center, but the biggest reason to stay on center at long range is to have adequate windage adjustment available.