21 May 12
Last weekend, at an Urban Rifle Course in the Midwest, a student brought a Ruger Mini-14 with a Trijicon optic forward-mounted on a rail. Unfortunately, the rail was anchored, via four shallow screws, into the plastic forend.
The rifle itself ran fine, but optic and mount were wobbly and unstable, and, not surprisingly, the rifle would not hold any kind of zero.
We eventually had to change rifles. He used an M1 Carbine for the rest of the Course, which ran fine.
An amateur “gunsmith” had foolishly plunked the rail onto to plastic handguard, assuring my student that it was all just fine.
The lesson here is that rails attached to unstable bases are suitable only for accessories like co-axial flashlights, where some slop and wobble is sufferable. Conversely, sighting systems, to be useable, need firm mounts.