Well, I took delivery of the (short) Troy BattleRail and performed a careful study of the situation and came to a realization that there is NO WAY what-so-ever that the rail can be installed EVEN if modification were an option.
While I'm still awaiting the Carolina Shooters hand guard anchor/mount ($59.95+ shipping!), I can see that it will be going back also.
The Troy part is gorgeous. While it is really well engineered and manufactured, it just can't accommodate the x39 Vepr's extra-stout barrel and accompanying fittings.
While I -might- comsider using it on my W.Works milled 74 (and MAYBE try to fit it to x39Vepr later), there is just no economical way to use it on the Vepr.
The upside-down saddle shaped mounting blocks of the Troy hand guard are too narrow (and shallow?) to fit over the Vepr. I'm uncertain whether custom sized copies of these blocks would even be possible with the existing Troy tube. Modifying the originals to work on the Vepr doesn't even look to be in the realm of possibility because of too little material, if the channel for a cleaning rod weren't there, maybe, but it's too tough to determine any further without a possibility of leaving tool marks on the parts and eliminating return for refund.