Retrofying my 1911

[Fang]

We all know that the 1911 likes to yank itself around under recoil, but not many are aware that the degree to which it does this is a relatively recent development. The wide curve on the bottom of the firing pin stop was only introduced in 1924 for the M1911A1 modifications; and described a radius of 7/32". Prior to that, the firing pin stop's radius was only 5/64"--much smaller.

The effects of the smaller radius were twofold: First, it gives the hammer greater mechanical advantage over the slide when the slide attempts to recock it during recoil. Consequently, more inertia is spent recocking the hammer, so the slide doesn't come back as hard or as fast. As a result, many report a noticeable reduction in recoil.

The downside to this positive effect is that with the new firing pin stop in place, it becomes far harder to hand-cycle the slide with the hammer down. It was complaints about this difficulty that resulted in the firing pin stop being changed to the larger radius. (Of course, one could always just cock the hammer before cycling the slide, but nooooo..) See here (http://forum.m1911.org/showthread.php?t=13060) for more details.

It's also worth noting that the M1911A1 saw a change from a straight mainspring housing to the curved one common today. This was also due to the complaints from soldiers who claimed the gun shot low. The response? Arch the mainspring housing so that the gun naturally pointed higher.

I'm blathering on about all this by way of preamble for my next little 1911 experiment: I'm going to take my 1911's mainspring housing and firing pin stop back to the pre-A1 configuration and see what JMB intended the gun to shoot like. I bought an EGW ovesided firing pin stop this week, which I will be fitting to my project 1911. I also have a nylon mainspring housing which will be swapped for the current arched MSH on a provisional basis to see what effect, if any, it has on the ergonomics or shootability. (Note that the other A1 features, such as the trigger scallops on the frame, the larger grip safety, and the longer thumb safety, will not be altered; these are all universally positive enhancements with no negative side effects.)

To test, I'll fire some ammo with the gun in its current A1 configuration, then swap out the firing pin stop. After shooting some more, I'll change the mainspring housing, then shoot it a whole bunch. After that, I'll move back to the rounded firing pin stop, shoot more, then move back to the old mainspring housing, too. After I've gotten used to the original A1 configuration again, I'll switch both firing pin stop and mainspring housing at once and see if there's a dramatic difference.

Stay tuned...

[Fang]

First off, I learned that moving the mainspring between two housings at an outdoor range can best be described as "challenging." Nonetheless, I perservered and came away with several conclusions.

The reduced-radius firing pin stop does indeed reduce recoil, although it's not very dramatic. Mostly, it removes the little snap that jerks the sights in random directions at the end of recoil. My mainspring is a little old, though, so perhaps a brand new 23-pounder will help. The larger size helped keep the extractor from clocking and made extraction a smidgen more predictable, though, so it's definitely a keeper.

I was surprised to find that I liked the flat mainspring housing. It made it much easier to grip the gun correctly, with the butt under the heel of my hand so that the 1911's axis aligned with the bones in my wrist and forearm.

This experiment also revealed something unexpected, but entirely appropriate. When gripping the gun correctly with the mainspring housing under the heel of my hand, a longer trigger would have positioned my index finger for a perfect rearward pull. It makes sense, and indicates that JMB really thought this out: The 1911's ergonomics as originally designed are set up to mitigate the recoil of .45 ACP; replicating part of those ergonomics (in this case, the mainspring housing) reveals the purpose of the rest of the system.

It's as if Browning put a lot of thought into the design, or something.

[Fang]

It turns out that my firing pin stop was filed incorrectly, causing the lower edge to be uneven. That means that it was bearing unevenly on the hammer, which may have contributed to the lack of perceived recoil. Smooth, Fang; smooth. I'll need to fix that and report back.

[Sim]

I was surprised to find that I liked the flat mainspring housing. It made it much easier to grip the gun correctly, with the butt under the heel of my hand so that the 1911's axis aligned with the bones in my wrist and forearm.

I swapped my mainspring housing for a flat one and haven't looked back. It's so much easier to grip it with the flat housing.

[larryh1108]

Interesting! The 1911 is a great design by a great man. If you study the details it is an amazing piece of machine. 1911's should be classified as an addicting, mind altering drug.