Greetings Everyone,
Trying to help my buddy out with his DPMS AR10. It is a sportical version, with a high profile rail on the upper receiver. When measuring the height of the rail on the UR at the bottom opening of where you insert the charging handle, it measures approximately .75 inches (see photo).

https://www.dropbox.com/s/vj9i50hjsvb7mb7/20161026_202808.jpg?dl=0

When measuring from the top of the charging handle opening, the top rail measures approx. 10/16 of an inch (see next photo).  

https://www.dropbox.com/s/q8tzb52lqxpn56n/20161026_203003.jpg?dl=0

The problem we (or he) are having is finding a free float tube with a high profile that mates the rails evenly from the upper receiver.  So far, he has tried an Odin M-LOK 15in rail and a VTAC Keymod rail. Both significantly fall short of the upper receiver.  Granted, no optics or accessories would be mounted so that they bridge the gap between the upper and free-float tube, but the difference is...ugly, to say the least (see photo).

https://www.dropbox.com/s/osk6kqqoyin25sv/IMG_10521.jpg?dl=0

The gunsmith was helpful in trying to find a free-float tube that would match up.  So far, no luck, he had other brands in stock but all fell too short.  I understand that UR rail height varies from model to model and even year to year of uppers made even by the same manufacturer.

The brand/manufacturer of the rail is insignificant, keymod, mlok or quad rail is insignificant. He just wants something that fits, in that the rails match up across the length of the weapon with minimal gap or height difference.  If you have any suggestions of a FFHG tube that will match up to the DPMS sportical, given the dimensions I've provided, please respond.

Any suggestions would be greatly appreciated, feel free to PM, email or post in this thread, although email would be fastest so it hits my cellphone,

Thanks in advance!

Good luck...the sportical  has that ridiculous raised upper.    I am not aware of any rails that meet your criteria.

They have three profiles..low...high...and super high. My Oracle was high profile and I ordered a 15" rail from Veriforce Tactical....My Aero is High profile as well and I ordered a 17" FDE rail from Juggernaut Tactical. Usually they will designate wether the rail fits high or low profile. .750 is high profile and if you read the specs pn the rails they will tell you if they fit.

Solid advice, will check those two brands out and share the results.

Well my buddy just stuck with his current rail despite the offset, thanks for the suggestion.