Assistance with Stith mount screw removal

[Southmountain]

I'm trying to remove a Stith mount from a Remington 721. There is a middle screw in the picture, attached, beneath the label "M1R" which I don't know what to do with. The top and bottom screws have been removed, but the mount is still stuck on the receiver.

This middle screw does not appear to be an allen, flat, or anything I've seen before. Perhaps it's been stripped, or rusted.

Anyone here have experience with these Stith mounts and could give me advice on how to remove this from the receiver?

 

[troy fairweather]

Is the remaining screws head stripped, if so this sounds a little bubba but works. Find a Torques bit that is just bigger then the striped out hole, grind the tip of the bit so it's more flat they have some bevel you don't want that. Try heating the screw up some to loosen any thread locker or dried oil. Get a small hammer and tap the bit into the hole. The bit will engrave the star part of the bit into the rounded out screw head, do this as much as you can. They you should be able to loosen the screw.

 

[Southmountain]

Thanks for the advice. It worked like a charm, took less than 5 minutes and saved me a trip to the gunsmith.

 

[troy fairweather]

Ok good, it sounds crud but works most of the time, I think the shock of tapping the bit in helps some to. If you have a bit driver with striking head you can turn and tap at the same time.