Building a 1911: Fitting the Firing Pin Stop

Most firing pin stops are simple drop-in parts which allow the prudent 1911 builder to quickly bring together firing pin and extractor, dust off his industrious hands, and move on to the next step of his project.

But NOOOOOOO we couldn’t be having that! This 1911 would use an EGW oversized firing pin stop, which requires (as it turns out) a suprising amount of fitting.

There’s a good reason for this choice, though. Two good reasons, actually. First, an oversized firing pin stop must be fit to both the slide and the extractor, so it holds both together tightly. This prevents the extractor from wiggling around in its channel and ensures more consistent extraction and feeding.

The less well known reason for using an oversized firing pin stop is that it requires stoning a radius onto the bottom of the stop, which permits creating a much smaller radius than is commonly used in 1911s.

Most modern 1911s use features introduced in the 1920s as part of the A1 set of modifications. These changes included nods to comfort (longer grip safety to prevent hammer bite), acknowledgement that these things weren’t being used on horseback anymore (narrower hammer), and a bevy of features to make the pistol easier to use for people with small hands (arched mainspring housing, short trigger, and scallops in the frame at the rear of the trigger guard). The last, and most often overlooked, change was increasing the firing pin stop radius so that it was easier to pull the slide back while the hammer was down.

The reason the increased radius helped is because the base of the firing pin stop acts on the face of the hammer as the slide comes back. The more gradual the curve on the rear corner, the more easily the slide pushes the hammer back. This is great if you’re trying to cycle the gun by hand without grunting, but nothing is free: Under normal recoil operation, the larger radius gives the slide greater mechanical advantage over the hammer, increasing the force with which it flies to the rear. The net result is greater perceived recoil.

Given that most modern 1911s have already restored several of the pre-A1 features such as the long trigger and flat mainspring housing, I decided to add another throwback in the form of a small radius on the firing pin stop. It would be interesting to see what effect this would have on recoil in conjunction with a few other modifications, but I’ll save that for a future chapter. For now, there was some filing to do.

Not some. A lot of filing.

The firing pin stop looks small and innocent prior to starting work, but it ended up requiring the most hand fitting of any part I’ve yet touched. This is by design: It’s intentionally oversized in every dimension for the express purpose of requiring fitting, which is fine–much better than a supposedly drop-in part which requires extensive reworking.

So let the reworking begin! I started by reducing the stop’s thickness the easy way, by rubbing its flat surface on a sheet of sandpaper atop a piece of glass.

Eventually the stop was thin enough to permit its edges to fit into the slot, but only when jammed in at an angle, because the piece was still too wide. Easy enough to fix.

Once the firing pin stop was thin enough front-to-back and side-to-side to fit into the slide groove, the next problem became apparent:

The top of the firing pin stop was too long, placing the hole for the rear of the firing pin too low. Filing the top of the stop was where things started to get tricky due to the curves on either side, which had to have their radii maintained in order for the firing pin stop to move up.

Slight digression: The firing pin in question is titanium and is paired with a Wolff extra-strength firing pin spring in order to make this 1911 as drop-safe as possible. On the last 1911 I built, that spring combination prevented primer ignition, but on this build I intend to use an extra-strength mainspring to overcome the lightweight firing pin and overpowered spring. An additional benefit of the heavy mainspring is that it will increase the effort required to cycle the slide, hopefully further reducing perceived recoil. Confirmation will need to wait on testing though. For now, back to our regularly scheduled firing pin stop fitting.

At last the firing pin fit through! Now it was time to fit the stop to work with the other part with which it interacts: the extractor. The cutout on the extractor was narrower than the stop’s notch in the side, so the side of the firing pin stop needed to be filed down to fit the extractor.

For the first time, all slide components except the sights were in place.

However, as you may have noticed in the above photo, the bottom of the extractor was a square edge. I wanted a small radius, but not quite that small. It was also a bit on the long side, so first I filed it flush with the inside of the slide, then slowly and laboriously filed and stoned a radius into the outside edge. If you’re a perfectionist, this process is equal parts delight and torment: delight at the subtle, nearly subconscious attention required to blend the shape by hand, torment at all the little tweaks and adjustments required and how it’s never quite perfect.

Eventually the radius reached a point I considered a little on the small side, but close enough. It was also not quite perfect, but good enough. I’d wait until the hammer was installed and then examine how it lined up with the hammer face before doing further adjustment.

For now, it was just nice to see the rear of the slide looking familiar.

Chris

Chris has absolutely no qualifications to justify speaking with authority on any gun subject whatsoever. He compensates for being a poor shot by embarking on quixotic gunsmithing projects of both mediocre quality and dubious value. Because his taste in firearms runs to overpowered and outdated designs, Chris' opinions on guns should be treated with suspicion.

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