They don't tell you... - Uncle Mike's Hammer Extension

I purchased this extension for my Henry 17HMR as I had installed a scope on the receiver. This extension definately made it easier to cock the hammer as the scope is very close to it. I was shocked to read in the directions for the extension that they recommend you file or grind a groove for the set screw to grab into. I don't want to file on my hammer so I installed it anyway and so far, after about 200 rounds, it has not come loose. Also, the directions state not to use it on a hammer with serrations. Why did they state this extension fits a Henry rimfire? They have serrated hammers! It is working on mine though but I haven't removed it to see if it has done any damage to my hammer.
Pros: Simple to install and very useful under a scoped rifle.
Cons: They want you to file your hammer.

This review was written in the old system and had content requirements that are different than reviews written today.