Hop Window Guide/Jig for Smooth Barrels (H8R)

This jig simply slides over and into the barrel, then the whole thing is clamped into a vice or clamp. The lips of the vice keep the file from going to deep and help make a level opening, the jig gives proper inside and ouside support to the barrel to keep it from warping when tightening. Please do not over tighten with vice or clamp, just enough to keep it from moving aorund when filing. 
This jig can be used to crete a window in a smooth barrel or extend an existing window for an extended hopup effect.
Also available in a traditional layout with notches that lock into the cutouts on the side of the barrel to help center it. http://shpws.me/Ot1E