Anyone put a quaility rail type handguard on one of these rifles.I was looking at a 2-piece.I took the stock handguards off and they measure 6 and5/8 inches.Will any carbine length ones drop in,or am I going to run into trouble?

6-5/8" is standard carbine length. Beware some are calling "mid-length" handguard rifles "carbines" as they're also 16" barrels.

A rail like this will not be suitable for optics, but just fine for lights and vertical grips.

-- Chuck

Let me try again.I am looking at the Troy MRF-DI.They advertise as a 7 inch unit,will they just drop in,replacing the stock,shorter handguards?This is basically the question I hope someone can answer.Sorry I wasn't very clear in my first post.