‘Making’ a Nickel 1911 Mainspring Housing

It took the Ordnance Department thirteen years to discover that the 1911 pointed and handled better with an arched mainspring housing. As I recall, it took me about thirteen hours to reach that same conclusion.  My revelation occurred about halfway through my second day of NRA Firearms Instructor Development School. It was August ’91 and we were shooting in a big square hole in the ground with 98 degree temps, high humidity, no cloud cover and NO wind. The course called for 800 rounds of pistol ammo over three days, which sounds like nothing until you consider that 80% of them were expected to find their way into one of the little scoring boxes of a TQ19 Target.

I was not shooting my old 1945 Ithaca as well as I should and aside from vision blurred by the sweat pouring in my eyes, I couldn’t figure out why. My shots were stringing vertically and I knew it was not the gun. I’d recently installed a flat mainspring housing on the gun because, well, just because. All the cool kids had them and all the cool 1911’s were being furnished with them. But Topeka was a long way from home and I’d brought a few parts along, including the old arched housing that came on the gun. On the next break I scooted back to the hotel and changed it out. By the end of the afternoon, I had my mojo back and those little scoring boxes we getting riddled!

My Nickel Rock Island 1911A1FS came with the flat mainspring housing furnished with their guns. It was just OK with Pachmyrs on it, but I needed an arched housing to make it feel right. I called Armscor and learned that none were available in nickel. I scoured the usual sources, learning that I was going to drop a C-note by the time I had one in my hands. The Rock is a good pistol- but I’m not putting a $100 mainspring housing on it. I ordered an arched, stainless John Masen mainspring housing for around 20 bucks, with the intention of polishing it to match the gun’s finish. The damn thing was WAY too long and in machinist terminology, they ‘missed the hole with the part’. It would absolutely not pin into any 1911 frame I tried it in, until I re-drilled the hole. Now I’ve installed a lot of mainspring housings and I’ve never seen that happen, so I had begun the refinish work only to find it wouldn’t fit. I was beginning to get pissed.

To Brownells credit, they offered to exchange or refund it. I took the first option, firmly believing the first one was a fluke. Wrong- Masen was on a roll! The second one’s crosspin hole was still off, but correctable by some creative reaming. These parts are castings and this is the stainless finish you get to work with. Note that Masen & Company didn’t bother to chamfer the mainspring  cap retaining pin hole, either.

I started by filing all the visible flats, to remove mold marks and get a workable surface. I took about 1/8” off the bottom too, to get a respectable fit with the frame. Then I cleaned up the cast-in checkering with a triangular Swiss file. My goal was to reasonably match the checkering on the slide stop.

Next I broke all the sharp edges, which resulted from filing the flats down, and I knocked the tops down on the checkering to make it user-friendly. Never know when you might need to shoot 800 rounds in 98 degree heat 😉  Finally polished the flats with some 600 silicon carbide paper and hit the works with Iosso Gunbrite on a cloth polishing wheel. While not perfect, the results could have been worse. And the results on the range were perfect- at 25 yards I shot it fully as well, one hand or two, as I did with the Pachmayrs on it. That’s a win in my book.



4 Responses to ‘Making’ a Nickel 1911 Mainspring Housing

  1. Mossyrock says:

    It only took you TWO John Masen mainspiring housings before you got one that would work??! You need to go to Vegas while you are still on a roll.

  2. Sarge says:

    Mossy, I’d used a few Masen slide stops, etc. on friends’ pistols that they just wanted to get running for a little money. I plugged one of their parked MSH into a Springfield a few years ago with no trouble. So I was a tad surprised a the difficulty with these two.

  3. Bruce Beckwith (Drago) says:

    I’ve used Masen flat MSH’s for many years in Springfields, and Colts without any issues; but it has been a while since I’ve bought one. Sargeare the demensions of the RIA frame the same as Colt and Springfield?

  4. Sarge says:

    As nearly as I can tell Bruce, the RIA’s only significant divergence from the blueprint is its weird radius at the front strap. I’m sure both the RIA and Springfield have gone through other changes over their years of production and you’d really have to examine individual examples and go from there. I did try each offending Masen MSH in the resident early Springfield 1911-A1 and it was obvious the problem was with the part itself.

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