Originally Posted by
RevolverRob
The core idea is a more heads-up position for CQB work and/or mounted on a weapon where a check weld is difficult to establish. You don't need a cheek weld, more of a "chin weld" to get a nice view through the optic.
A lot of the braces/tubes out there for pistol-type ARs/PDWs are thin and have short/flexible "butts" (braces) that don't provide the firmest base to begin with, making cheek welds more difficult to acquire and keep when shooting.
I'm interesting to see what Craig thinks after running some live rounds through the mount. I'm 'skeptical', but I was skeptical of higher mounts initially and have come around to the idea after some use. A lot of it depends on your view of how the stock/brace/tube shoulder interface. A tubed-only PDW provides such a small contact patch for shouldering that a nose to the charging handle is very difficult to establish with shorter height mounts, even for a short necked dude like myself.