The HS Precision stock that I fixed up last year was hollow in the middle. I'm pretty sure it came off a Model 700 Varmint, it had the thin recoil pad too. I installed a grind to fit recoil pad but cut some off the back to clean it up and not make the LOP too long.
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I installed some screw in threaded inserts for the new recoil pad screws but these were mainly to provide clamping force when I glued the new pad on. I used regular two-part clear epoxy to do that, nothing to complicated.
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