We'll start with the frame. A beavertail grip safety is a given on any custom 1911 since not only does it offer a larger surface area over which to distribute recoil, it also offers a much higher grip on the pistol when fitted correctly. Moving the hand closer to the bore axis greatly aids in controlling muzzle flip. Some "custom" pistols exhibit less than perfect fitting of this part to the frame. Less than perfect is unacceptable when a client is paying the kind of money that this costs.
Let's get on with this part. There are "filing jigs" commercially available to facilitate filing the frame horns to accept the grip safety. The problem is that when one of these is used, it invariably results in unsightly gaps where the part meets the frame. All beavertail safeties are investment cast and the internal contours and radii are never perfect. The first action item is to true the internal radius of the grip safety, otherwise it can never be fitted seamlessly to the frame.
After the frame horns are cut and roughly contoured, the smoking and filing begins. This is no different than blacking the barrels down or inletting the stock on a fine shotgun. It takes MUCH longer than using a filing jig but the results are well worth the effort.
Once this part of the job is done, the external fitting can begin. I always think of just about all aftermarket "custom" parts as blanks to be finished by the gunsmith.
With the barrel and bushing properly fitted, the rear of the slide was filed and polished to perfectly mate with the back of the frame when the slide is in battery. The extractor and ejector are installed for this operation as they form part of the rear contours. The top of the slide was serrated, cuts for Novak front and rear sights are made (a Kensight adjustable is used) and the slide is treated to a decorative border at the topside and beveling on the bottom edges. The front strap was serrated (20 lpi) in a diamond pattern (this client's preferred design) and material was removed behind the triggerguard to facilitate a higher grip. The final frame modifications are a beveled mag opening and trued contours.
The finished job.