bladesmith3 from United States, CO Public Profile

this is the third rise ra-905 handguard that i have bought. the others were the 13.5" version. the 13.5" version has been vastly improved since this 10" model was made. ok.. the 10" that i just got does not have the reinforcing raised portions near the receiver/bolt end that is present on the longer versions. here is the worst part of the 10" version. there is no relief cut by the receiver pivot pin. so if the rail is against the upper receiver, then you cannot put the upper on the lower because of an interference fit with the pivot pins. i tried this on 5 different lowers, several brands, no way could it work. i am a retired machinist. luckily i had the longer version on hand to see what changes were made in design to make the longer ones work. i machined the handguard by the back edge near the pivot pin location, to closely match my other rise handguards. that cured the mounting problem. BUT it was not the only problem. no matter how tight i tightened the mounting screws the handguard was loose and would move up and down A_LOT! the slot that the barrel nut anchor goes in was cut on a taper. there was no easy way to fix that. i removed the wedge and tightened the screws until the handguard was tightly mounted and the measured the width of the slot from front to back that the anchor wedge goes in. the wedge was about .165" but to make the rail work the wedge had to be ground at a taper from .150" in the front to .133" at the rear. that cured the mounting problems. i darkened