1911 MIM parts

I had a guy come to me a few years back with a NRM 01991 Colt Government model. He requested that I replace the MIM sear and disconnect with his new parts. We'd discussed it some weeks earlier, and I told him that it was probably a waste of time and money.

After the swap, I asked him if he wanted to keep his old parts, and he said no...so I did a little demonstration for him.

I laid the sear on an anvil...cupped side down...and gave it 2-3 brisk whacks with a 4-ounce ball peen hammer. It didn't shatter into a million tiny pieces. It didn't even crack...and when I installed it in one of my pistols, it functioned just fine, albeit with a pretty rough trigger action.

Then, I clamped the disconnect up in a vise and whacked it with the same hammer. It bent, but it didn't break.

Good MIM is pretty good stuff. Bad MIM...not so much. Colt has apparently found a good vendor for its MIM parts. In the early days, Kimber did likewise. As time went on, they either changed vendors or their current vendor's QC went down. From what I understand, that problem has been rectified, and they're using good MIM again.

Another part of the MIM problem is using it in applications where it really shouldn't be used. As a rule, it doesn't fare very well with impact. That may have changed with better technology, but I wouldn't bet too heavily on it.

The big problem is that...without an X-Ray or magnaflux test...it's impossible to determine whether the part is good or bad unless it has a visible surface flaw.