I got kit from Steve's guns last night.. The smoothing of the bolt, the portion that the hammer rides on made the biggest different. Mine must be a factory freak because it was pretty darn smooth from the factory. Remove material on the extractor, bolt, trigger return spring help. The extractor is wide as it is thick, by thinning it down (image a rainbow shape) it help climb over the case rim better. I just remove a little not as much as the DVD. Also is change the ejector spring. When you close the lever and the last pop or wall you hit is the ejector spring as it is tough. I did remove 1.5 coils off my hammer spring