If the tube isn't straight (perhaps it was taken out of the mold prior to being 100% cooled), then as the buttstock is collapsed, it gets tighter. When fully collapsed, it can take quite a bit of force to overcome the friction. Not gorilla arms, but still quite a bit of force. And stopping that in the 5" or so before the pin hits the back edge of the channel ain't easy either...

However, I sanded the flat portion some more today, and now it requires *almost* no force to extend or collapse.

Next, I'll look at a replacement stock.. I like the cheek weld on my VTAC....

Thanks, all, for the sound advice!