Policetacteam, Mrmojorising,
The locking bars of your vertical grip will engage the crosscut at different depths, depending on the rail's mfg., and where in the tolerance range the crosscut was made.
Regardless, the bars were designed to engage properly within the entire tolerance spec of MIL-STD 1913.
The instructions were written around the KAC RIS/RAS, and when installed the locking bars are fully seated at the top of their ports. This will differ slightly with other rail mfgs. Any force applied to the grip will only 'wedge' the bars further into the crosscuts.
Also, the locking bars only prevent fore-aft movement. They do not affect side to side movement.
This is controlled by the dovetail cut itself.
Our grip was designed for MIL-STD 1913. No other.
Some commercially-offered rail systems may claim they are MIL-STD 1913, but, upon dimensional inspection are far from it.
Some mfg's have 'edited' their rails to alter the mandatory .367 MIN dovetail and base height. Probably to reduce the overall height /width of their handguard. This invites mounting problems with our product, and creates the 'pounding on' issues, as there is a collision between our grip, and a rail with insufficient accessory clearance.
Some may have slightly undersized dovetail dimensions. This is exaggerated by the leverage factor of a vertical grip. .002 extra clearance at the mounting point may translate to .030 movement at the end of a 4 1/2" grip.
If a rail has the mandatory .835 +0/-.005 dovetail width, and .617 +0/-.010 base width, the grip will not 'wobble', nor require undue force to install. This is MIL-STD 1913 dimensioning.
Let the buyer beware.
Best,
Jeff
TangoDown LLC