I’ve got a problem with a Ruger Mini 14.

4

4570Rick

New member
I’m a 30-year veteran machinist and have worked on everything from plastics to exotic alloys to carbon composites. I’ve worked in the Aircraft, Tooling and Prototype, Robotics, Nuclear, and Plastics Injection Molding Industries. But I have never been as frustrated as I am today. I do some odd jobs for a gunsmith friend of mine in return for favors. The current item is a stainless Mini 14 receiver being drilled and tapped for a scope mount, one blind hole over the chamber and two thru holes just in front of the rear sight. The material is some nasty stuff. It ate my center drill, two #38 HSS drills. I got a carbide “gun drill” (OSG Series 200 straight flute micro grain carbide drill) and no problem. Then I try to tap the thing using 5-40 HY-PRO 280 series taps designed and engineered to be used on stainless steel. I have destroyed 6 taps and haven’t successfully taped one hole. Has anyone out there experienced anything like this or is there a certain type of tooling that works on that stuff Bill Ruger calls Stainless steel. Tomorrow, I’m going to try a “Roll Form” tap or something like that. I could sure use some feedback.

4570Rick
 
Well

A 38 drill is .1015 so ya might try taking a piece of scrap steel and drill it with a 37 @.1040 and tap it and see if it would work Not the best alternative but worth a shot. Good luck to ya.
 
4570Rick, I have never had to do it so you may know more about the properties of stainless than I do, but I've read that stainless can be annealed. Given what you've run into I might look into spot annealing. George

Rick, I just spoke with a machinist friend of mine and he says he always drills one size bigger in stainless as Mike suggested. George
 
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