Just to play devil's advocate--why do you even need to fire it to break it in?
Realistically, your just going to have to shoot it til it works or to a point you cant take it any more and get rid of it.
The more you shoot it and troubleshoot it, the more it costs, and you have to add your time and aggravation into that mix as well.
If you like the gun, it will probably be a longer process.
If it takes 500 rounds to break it in, how many more rounds does it take to prove its truly broke in? Another 500?
What your going through is one of the reasons I no longer buy or carry 1911's. I got tired of fiddling with them.
This is what my UC looked like.....
It sure was pretty, and it was a shooter, accuracy wise, if only it had been reliable.
This old nasty looking thing on the other hand, has been 110% reliable over its fairly long, hard life, and is still so to this day. Then again, it was built to the original specs, buy the original maker. It rattles when shook, and has none of the add ons deemed to be "necessary". Other than an occasional bad reload here and there, its never missed a beat, right out of the box.
If you want an accurate and reliable "small" .45 with none of the small 1911 issues, look in this direction.....