Allen type strain screw needed for S&W

[oldhenry]

I've converted a N frame S&W from Square butt to RB. The process all but eliminated the recess for the strain screw. In the past I seem to remember some custom "smiths" installed an allen type screw. Revolvers smiths are becoming few & far between.

Does anyone on the forum know of a source for this type screw?

Any help is appreciated.

Henry

[rintinglen]

I bought one from my local home depot that fit. However, if you ground the forestrap that much, you may have to thin the existing screw head to get it to drop to the level of the trimmed down forestrap.

[oldhenry]

I bought one from my local home depot that fit. However, if you ground the forestrap that much, you may have to thin the existing screw head to get it to drop to the level of the trimmed down forestrap.

Thanks for the response. I'm afraid the recess is practically non-existent. To reduce the dome of the existing strain screw would put it in the paper thin category or increase the recess depth with an end mill (last resort). A allen type replacement is the optimum solution. If I don't hear of a source from other members, I'll check with the local nut & bolt dealer. A thread match is all I need: I can "adjust" the length.

Henry

[tazman]

I assume you have the original strain screw in hand. Take it with you to almost any hardware store and find a standard set screw that matches the threads. They come in a lot of sizes and are available in most hardware stores.
Are there any Fastenal stores in your area. They have a large selection in some offbeat threadings.

[kir_kenix]

I'm pretty sure they are 8-32...but I'm going from memory. Fastenal or any industrial supplier will have them on the shelf. Even menards or home depot will probably have them if your willing to buy a packaged assortment.

I've used grub screw/set screw before when I bought a disassembled 'Smith-in-a-ziplock bag-special.

[oldhenry]

Tazman & Kir Kenix,

We have a Fastenal store here + we have one much better. Albany Nut & Bolt has a much better inventory in SAE & metric. They have taps & dies also & this will be plan B should I strike out on a thread match. I'll be there Monday morning when they open.

Kir Kenix, I hope you're correct on the 8-32 (although it'd be like S&W to do something different...….just for the heck of it).

Thanks guys,
Henry

P.S. Many thanks to Sierra1911 for the RB template...…...love this forum.

[Petrol & Powder]

The only problem with a set screw is it lacks a shoulder to act as a "stop" when the screw is bottomed out. The head of the S&W strain screw bottoms out in the pocket (recess) when the screw is fully tightened. The tail end of the screw that acts on the hammer spring is not what locks the screw in place when it's fully tightened; it is the tension between the threads and the screw head that provide that locking. Without a head on the screw, there's nothing to hold it in the right position.

A set screw with no head could work but there's nothing to keep it from backing out on its own. A little bit of Loctite may be a solution.
Another path would be a thin nut on the screw between the frame and spring (if there's room). Or, a set screw could be used and a second hole drilled and tapped at a 90 degree angle and a brass locking set screw could used to lock the strain screw. That locking screw would be covered by the grips.

Good Luck.

[oldhenry]

The only problem with a set screw is it lacks a shoulder to act as a "stop" when the screw is bottomed out. The head of the S&W strain screw bottoms out in the pocket (recess) when the screw is fully tightened. The tail end of the screw that acts on the hammer spring is not what locks the screw in place when it's fully tightened; it is the tension between the threads and the screw head that provide that locking. Without a head on the screw, there's nothing to hold it in the right position.

A set screw with no head could work but there's nothing to keep it from backing out on its own. A little bit of Loctite may be a solution.
Another path would be a thin nut on the screw between the frame and spring (if there's room). Or, a set screw could be used and a second hole drilled and tapped at a 90 degree angle and a brass locking set screw could used to lock the strain screw. That locking screw would be covered by the grips.

Good Luck.

As it turns out the 8-32 is the correct size. The square end of the set screw was not the best shape, so I chucked it up (gently) in my hand drill & working against my belt sander (carefully) I was able to get a better shape. I also altered the length to match up with the OEM strain screw length (underside of head to engagement with the main spring)

Your suggestion of a locking nut on the inside of the frame is exactly what I need (there is enough room). Thanks for that input.

The RB conversion in conjunction with J. Miculek grips made all the difference......especially in DA.

Henry

[Petrol & Powder]

Oldhenry - If you're an Old School mechanic (and I'm betting you are) you probably have a set of ignition wrenches (tiny combination wrenches used to set ignition points and other small parts). That would be the perfect tool to tighten/loosen that thin lock nut.

Good Luck !