About 2 years ago, I saved my pennies and bought a Kimber Tactical Entry 2 with a light rail. This was the most expensive gun I'd ever bought at nearly $1500, but on the range, it proved to be worth every cent. It has also been my primary carry gun since that day.
Well, last week while shrugging into my shoulder holster in the parking lot after class, the thumb break had snagged on something and popped open allowing my rather heavy handgun to drop to the pavement.
Yes, that was stupid on my part for allowing the retaining strap to snag, but these things happen on occation. Well, it landed right on the bottom corner of the mainspring housing which caused the housing to break. 
Come to find out, the mainspring housing is made from plastic. I was pretty shocked to say the least. I've owned several 1911's over the years, and had never seen any main componet, even on cheap ones, made from plastic.
So, I went on line and got a steel mainspring housing from Wilson that was checkered at 30 lines per inch, the same as the front strap of my Kimber, for $45, then had to pay another $30 to have it fitted by my gunsmith. I'd have done it myself, but it required filing and I didn't have any cold blue to prevent it from rusting. I also want to keep my local gunsmith around, so some jobs are worth sending out.
Here's the plastic one.
And the new one in place.
The new one, with the fine checkering makes the pistol feel like it's velcro'ed into my hand.