There is nothing magic about making a .45 auto run. Having several, they all ran out of the box, but needed those little tweeks that I deem necessary, except for one, a Colt 01091 SS 1911A1. 1911's in .40 tend to be a little picky. At least everyone I have dealt with and I have a couple.
If I was going to buy a box stock single stack 1911A1 to play with, without wanting to put any more into it than was necessary, it would be a Colt model number 01091. They run. Mine eats every thing I have fed it. And I can hit a 6in plate at 25yds with it.
FYI, I have a couple of +$2000 single stacks. They run better than they look, and they look great.