1. Have you tried adding tension on the extractor, yet?
2. Also, inspect the extractor hook and hook mark on the empty case. They extractor may be worn or have been bent out of shape.
3. Also, check the Firing Pin stop fit. If the FP stop has become loose, then extractor may have some play.
My SS Kimber Target Custom II had extraction issues when new -- fixed (DIY) by adding tension the extractor and reshaping the extractor hook. Also, replaced the FP stop with EGW because stock part broke. The EGW FP stop fit better/tighter than the stock.
After the Extractor fix on the Kimber, It has been very reliable. I have shot it for a while (several years) with stock parts with no issues. I have since replaced the trigger, hammer, and sear with wilson combat parts.
Likewise, my STI Trojan (approx 2 years old) is very reliable (no issues out-of-the box).
The Kimber and STI are equally accurate but the STI has a slightly tighter fit. Also, shooting the STI feels slightly smoother than the Kimber.
- My STI has been handled and shot less than the Kimber. It is starting to show some normal finish wear on the front/back strap and the grip safety. The SS Kimber still looks new.
- I like the STI fiber optic front sights better than the plain black Kimber.
- STI grip feels slightly bigger than the Kimber using the same wood grip panel.
- High Grip Safety on the STI seems like it makes the pistol point a little higher than the Kimber.
I have held a Springfield Armory 9mm recently; Similar to the ones I have held several years ago, the fit is not as tight as my Kimber or STI but still good. Also, grip felt more comfortable than STI or Kimber (for me).
The STI spartan V looks good for the price.
BTW --- all these are single stack 1911s.
good luck and happy shopping.