12-12-2011, 11:31 PM
Grunt,
I had a similar question when I was building my rifle, and I searched ALL OVER trying to find an answer. Best I could come up with was that the height from the bore centerline to the top of the flat-top rail is very close to 1.2" (I actually had an exact number from a blueprint somewhere, but can't find it now). I would assume that most Mil-spec uppers will be the same dimension.
I found a useful chart that has lots of mounts listed, you can get it here:
http://www.maxicon.com/guns/optics/one_p...mounts.htm
For my combination with a Burris P.E.P.R. and a 1" scope, I came up with 2.7". That seems to work well with my set-up.
One cautionary note; when I was sighting-in, I started with my normal scoped rifle setting of "zeroed at 25 yards", then went to 100 yards, where I would have expected to be 3" to 4" high or so, pending final adjustment. I found that I didn't even hit the paper, until I dropped down a little, where I then had holes at the very top. The extra inch and some in the scope mounting for the AR puts the trajectory a LOT higher at 100 yards than I expected! I had thought that the Marines 37 meters battle sight zero would be close, but the scope mounts are substantially higher than the BUIS sight line.
Mack
I had a similar question when I was building my rifle, and I searched ALL OVER trying to find an answer. Best I could come up with was that the height from the bore centerline to the top of the flat-top rail is very close to 1.2" (I actually had an exact number from a blueprint somewhere, but can't find it now). I would assume that most Mil-spec uppers will be the same dimension.
I found a useful chart that has lots of mounts listed, you can get it here:
http://www.maxicon.com/guns/optics/one_p...mounts.htm
For my combination with a Burris P.E.P.R. and a 1" scope, I came up with 2.7". That seems to work well with my set-up.
One cautionary note; when I was sighting-in, I started with my normal scoped rifle setting of "zeroed at 25 yards", then went to 100 yards, where I would have expected to be 3" to 4" high or so, pending final adjustment. I found that I didn't even hit the paper, until I dropped down a little, where I then had holes at the very top. The extra inch and some in the scope mounting for the AR puts the trajectory a LOT higher at 100 yards than I expected! I had thought that the Marines 37 meters battle sight zero would be close, but the scope mounts are substantially higher than the BUIS sight line.
Mack