Pursing the posts on several different forums relative to screw-on bumper pads I found several different posters who opined that the base plates on 1911 magazines were "hard" and could only be drilled with a carbide drill.
That is just not true. The few 1911 base plates I tested (MecGar plus one unknown brand) with a file demonstrated a slight reluctance to cut, but the file did not skate across the metal without cutting at all. Therefore, not "hard" (as to a machinist anyway). Albeit, they may be described as somewhat "tough".
The common thread size and pitch for attaching bumper pads is tap size 4-40. The drill size for a 4-40 tap is #43 which is only .089 in diameter. Solid Carbide drill bits are very brittle...way more so than the more common High Speed Steel drill bits. In short, the chances of a non-machinist using a cheap home drill press with a solid carbide .089 diameter drill bit to drill the two holes in a typical 1911 base plate are not very good without breaking the bit.
However, the base plates are not hardened can be drilled successful. It is just that I would suggest using Titanium Nitride (TiN)coated drill bit to do it. The Titanium (a Gold colored ceramic), is coated on the High Speed Steel (H.S.S) and will cut tougher metal, while at the same time being less brittle and likely to break. Use high RPM's and a center punch to locate the holes. Or better yet, take a night class in machining at your Community College and learn how to do such things there.
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