In the 80's I built some where around 25 1911 parts guns. To keep costs down I use de-milled slides (Slide that were cut up and then 2 pieced were welder together). Some of the slides were less than perfect but you couldn't see any "bend". These slides always seemed to bind on the Fed-Ordinance frames I used. A full length guide rod was a simple and affordable solution. However, on my personal 1911, also built from parts the Essex steel frame and a re-weld slide work fine together. It has to with parts quality and price.

BTW: When my 1911 were sold nobody complained...because they were sold for $125 and later $140! I guaranteed them to go Feed and GO Bang! I fired every one, they kept 7 rounds on a paper plate at 25 yards. At the time, some factory Colt guns didn't feed reliably or hit a paper plate!