I have one mainspring housing left from the last time I made a few..... I dug it out and it was 2003 or 4. I made some out of aluminum because I wanted the forward step and it couldn't be effectively fabricated onto an existing aluminum MSH, which, anyway, at the time at least, there were none made of aluminum that I wanted to use.
Making them out of steel with the forward step is no biggie since welding or silver brazing the extra forward metal on is possible. You can weld aluminum, yes, but.... on things finer than trailer frames and such it doesn't always work out well. In recent years for steel ones I have often used Stan Chen's MSH's with the forward step. They saved me the welding or silver brazing. Other times I went ahead and made them as I have since I first did it in, I think, 1989 or 90.
But when I do a radical girth reduction, I still need extra metal as I need to add "hips", as in this one:
So.... I needed to make some more in aluminum anyway, and decided to make them with hips, so I made a batch in steel too. I made enough to offer some for sale. They will be a nice fit in the biggest, sloppiest frame, and need fitting on all others. Widths are a full .545 and .634, perfectly concentric. I've seen some pretty varied frames in terms of these dimensions and many where the frame slots are well off-center from the main body width, so..... that all needs to be checked. Rails are a full .085, again, so it can be made a no-slop fit in just about any frame out there. Not that it matters that much but on a gun that's costing somewhere between $3000 and the sky's the limit, nobody wants to feel the MSH shift in dry firing. I did not even cut a radius on the back side; these are not for the hobbyist and I figure a 'smith that's going to cut a pattern on the MSH probably has a setup to machine the radius and may want more, or less, girth, or an angle, or what-have-you. And I have left metal on it in case anyone wants to do my style of girth reduction. The reason for the hips is explained in this thread: http://forum.ltwguns.com/viewtopic.php?f=6&t=9678
And if a guy does not want the hips, just mill 'em off in the fitting process. In the next couple weeks I will get my process written down to go with the MSH's-- which I am calling MSH-F, for fitted. They are not the most bargain-priced MSH at $125.00 (NOW $67.00-- 10/24/2016
)but they are a lot of work to make on a small scale and offer a lot of extras like not having to peen or weld rails to get that no-slop fit. If these sell well I will make bigger batches and the price can come down.
The forward step is at .300 from the MSH retaining pin hole center and is perpendicular to the rails. This makes cutting the frame easy and should you need to trim this dimension on the MSH, it's easy to just put it in the mill vise and rest the rails on top of the vise jaws, no need for parallels.
More later, but for now some pics. Could not get them to post with the usual method, I'll have to work on that:
A big ol’ block of prehard chrome moly steel:https://www.flickr.com/photos/92534225@ ... hotostream
….gets squared up….https://www.flickr.com/photos/92534225@ ... hotostream
…..divided into four blocks, each will make two MSHf’s. More to come off first. Lots of blue chips on the floor.https://www.flickr.com/photos/92534225@ ... hotostream
Retaining pin hole and angled front surface….https://www.flickr.com/photos/92534225@ ... hotostream
Drill and ream the mainspring hole. Depth has to be just right and the hole must have a smooth finish.https://www.flickr.com/photos/92534225@ ... hotostream
Cutting the top profile.https://www.flickr.com/photos/92534225@ ... hotostream
Checking the top, back surface for proper location from the mainspring housing retaining pin hole.https://www.flickr.com/photos/92534225@ ... hotostream
Drilling the mainspring cap retaining pin hole. I got ahead of myself, this should have been done before the mainspring hole.https://www.flickr.com/photos/92534225@ ... hotostream
Cutting the side steps, front.https://www.flickr.com/photos/92534225@ ... hotostream
Side steps, rear, cut.https://www.flickr.com/photos/92534225@ ... hotostream
Separated, logo added, ready to go. One from a 1918 Colt thrown in for comparison: