Mechanical accuracy is a combination of many things ... tight tolerances without being too tight to cause binding .... tight barrel lockup so that the gun shoots the exact same way each time ... in the case of a 1911, the tolerances betweent the barrel and bushing, and bushing to slide matter greatly. OF course the trigger means a whole lot, but that is more related to how a shooter relates to the gun, rather than the mechanical accuracy of the weapon itself.
Certainly precision in every aspect of the machining process matters greatly, and of course that precision machining has to do with the original design drawings. If there is a flaw in the original design, no amount of precision machining can correct it ... in that case, precision machining only perpetuates the flaws.
I've found that MANY people don't understand that one gun can be considerably more accurate than another one, and those people go on and on that they can shoot gun A better than gun B, so how could gun B be more inherently more accurate ? Of course this just demonstrates the person's lack of understanding of firearm accuracy. Many don't understand how it's possible for a person to be able to 'outshoot' a given gun, either.
I had a discussion with a guy at the range who is a QC specialist for a company that makes pumps and pumping equipment for nuclear submarines. He maintained that the only accuracy difference between 2 rifles .... ANY TWO RIFLES ... was the amount of 'practice' that a shooter had with the rifle in question. I said ... OK Donny .... so you're telling me that ALL Rifles .... every modern rifle in existence .... if bolted into a mechanical rest so that no variables could change, would ALL shoot the same size group at 100 yards if given the same ammo and no variables could change ??? Mindblowingly .... he said YES. THis guy is inspecting pumps for our NUCLEAR SUBMARINES !! I tried to explain the concept of inherent accuracy to him, and he truly could not understand it. In his view, the only variables involved in target shooting is the shooter himself.
You can not evaluate the accuracy of a weapon by shooting a mag full at the range with your buddy;s gun. That's another thing you hear all the time ... many, many posters post things like ... 'If a Glock, or Sig, or CZ, or FN, or HK, or S&W, or XD, or whatever, is so accurate, how come when I shot my buddy's 'whatever' at the range, I couldn't shoot it as well as my Ruger 'whatever' ???? Well, I can think of about 10 things that could cause that, but I won't go into them now.
Original design, and the machining and tolerances behind it are needed for a gun to be accurate. All the parts need to work in harmony. This of course means that the parts can not batter themselves against other parts, as is the case in the SR9. I don't know what the reason for the 'peening' is in the SR9, but common sense will tell you that SOMETHING is wrong, either in the design, or the execution of the design, which is the machining and tolerances in the machining.