Building a Pistol

The FGW way...

Posted by Bobby on August 16, 2011

Since I am kind of a DIY guy gone pro and people often ask me about all the steps that I go through in building a pistol, I thought I'd start a thread here and show photos of the work being performed. This gun is going to Louisiana and the customer is a 3Gun and long range rifle shooter. He wanted a 9mm 2011 to compete with and pretty much left everything else up to me. Knowing this customer (he's a small framed lanky kinda guy) I decided to build him a full profile 9mm with some slide lightening. The purpose in lightening the slide is to reduce the cyclic mass. The goal is to take the bowling ball hammering back and forth on the frame and turn it into a tennis ball. The less reciprocating mass when properly sprung will have less perceived recoil and less front sight lift. In this particular gun, the additional weight in the nose of the gun will keep it pointed at the target better as well.

First off, we start with an STI slide and frame. The slide has no sight cuts, serrations, or logos on it at this point except for the Freedom Gunworks name.

For the first step, I'm going to indicate the slide in the mill in my modified Yavapai jig and cut the flat top. I indicate the slide from one end to the other to insure it is perfectly flat with 0.0005" from 1 end to the other.

To perform the "tri-topping" operation, I'm going to use a face mill and flat top the slide first. It's kinda hard to do this if you have sight cuts in the slide already as you'd just about cut out the front sight dovetail. I spin the cutter at about 1800 rpm and remove material the entire length of the slide.

I then roll the fixture in the vise and do the left side the same way.

And again for the right side.

After tri-topping the slide, I'm going to take some critical measurements from the frame and slide using some special tools I've designed specifically for making the measurements as accurately as possible. I want the hand lapping of the 2 surfaces to be minimal and I want a really tight slide to frame fit. The first part I'm going to machine is the bottom of the slide. When it comes to me from STI, the frame and slide will not go together, so I have to remove material from the slide to match the clearance between the frame rails and the frame. To do this, I hold the slide in the mill with the bottom up and indicate the bottom of the slide so that it is parallel the the milling table. This is important so there is no slop in the slide/frame fit either in battery or fully rearward. I use a spacer between the slide rails to keep from pinching the slide in from the pressure of the vise.

Now, with a .250 flat cut end mill, I remove the predetermined amount of material from the bottom of the slide.

Somehow or another, I forgot to photograph the operation of removing material from the frame. In that operation, because the frame is to wide to let the slide to fit, you have to remove material from each side of the frame rails. Also, in this particular build, we are using an STI .355 bull barrel. Since STI bull barrels only come with a Wilson/Nowlin ramp, the frame must be cut to accommodate that specific ramp. This frame already had the cut in it so I didn't get photos of this one but I will add some on the next frame. Most smiths hate doing the Wilson/Nowlin cut because of the additional set up and difficulty of the cut. It doesn't really bother me and I don't mind doing either ramp.

The next step in the process for me is hand lapping the frame to the slide.

Now that we've got the frame properly fitted to the slide and lapped in so it moves like it's riding on butter, we'll do the sight cuts. In this build, we're going to use a Dawson Precision 0.090" x 0.180" fiber optic front sight and an STI Bomar style adjustable rear sight. Let's start with the front sight. Again, we'll indicate the slide in the vise and use an edge finder to touch off on the end of the slide and zero the quill.

I like to make a relief cut with a flat end mill to full depth so the dovetail cutter has less stress on it. This will make for a cleaner cut and prolong tool life.

Next, I'll load in my dovetail cutter and zero off the top of the slide and cut 0.065" deep from left to right.

The finished product should look something like this:

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