Just a thought for the ones of you having feeding problems with aftermarket barrels(KKM, Barsto, Est). Not all the barrel chambers are the same depth, so the COL will have an effect on the slide going into battery! A little checking of the depth will help you in several ways, one being no feedings problems and second better accuracy, if you're reloading your on ammo!
You want the COL custom fitted to your barrel for the type of bullet you are using due to the ogive of the projectile and of course the barrel chamber. If the COL is a little to long the bullet ogive will engauge the barrel rifling causing the case to extend beyond the breach surface of the barrel not allowing the barrrel and slide assembly to go into full battery.
I hope this is helpful information!
Dan