What the heck is this?

[Bravo11]

I was looking at the Midway website for a weaver type rail for a BuckMark and this was on the list for Browning BuckMark accessories.
What is it and what is it used for?
http://www.midwayusa.com/rewriteaproduct/382070

 

[lindermant]

the Powers Series 1 is a hammer/sear stoning fixture

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=9853&title=SERIES+I+STONING+FIXTURE

the item you listed is an adapter for the PS-1 that allows you to work on the Buckmark hammer/sear