How difficult to swap MSH?

[c5367]

I've been looking at the Kuhnhausen shop manual, and it gives pretty good instructions. However, it make mention of punching out some pins to take out the mainspring housing. The manual is written for someone with a bit more 1911 experience than I have and doesn't describe that portion in much detail.

I'd like to try out an arched MSH in place of the flat one. Will I need to get new pins? How hard is it to get them out? I want to learn, but at the same time I don't want to butcher my new favorite gun. Any and all advice would be greatly appreciated. Thanks, and stay safe.

[Wolfgang]

You can use the same parts in the new MSH (unless it is an ILS SA) or you can get new parts and have two you can switch out in about 1.5 minits.

Look at page 14 of this:
http://www.springfield-armory.com/Manuals/1911man.pdf

If you DO NOT have a Springfield with the ILS you have a pin in the MSH, so ignore that part.

Page 17 puts it back together.

This may help, it may be confusing.


This may also help:

http://m1911.org/full_striping.htm

[Kruzr]

It's simple. Unless the gun is a Kimber, it should just drop in. (You have to make sure the Series 2 push rod is flush in the frame if you replace the MSH on a Kimber).
You will only have to deal with 2 pins. The first is the MSH pin. This is the dimpled one on the bottom of the grip frame. You drive it out from the dimpled side to the rounded side. Replace it the same way. This pin has a slot in it that the mainspring plunger on the bottom of the mainspring fits in. You will have to tap the pin out until the slot clears this plunger. Then you can pull it out. The other pin is the Mainspring cap retaining pin. You can see this one on the back of the MSH. It's the real small pin. With the MSH off, push down and hold the spring cap and remove this pin. Slowly let the cap and spring up. Return the parts to the new one the same way.
One more hint, put a rubber band around the grip safety when you are taking the MSH out and leave it until you have the new one slid up enough to capture the hammer strut. This will keep the sear spring from slipping out of place.

[ceemack]

I just did this for the first time myself this past weekend. The next time I do it, it should be pretty simple.

I installed a Smith & Alexander MSH in my RIA. I learned that--ahem--minor fitting was required.

I wound up needing:
1. 1/16" and 1/8" brass punches.
2. A 1/8" steel punch.
3. A hobby hammer.
4. A bastard file.
5. Some cold blue.

Removing the old one is fairly simple. There's a pin at the base of the bottom rear of the grip frame that holds the MSH in place. Drive it out using a brass punch. Go from left to right, and drive gently. You shouldn't have to force it.

Once the old one is out you need to strip it for the internal parts. If you look at the top of the MSH you'll see a hole, about 3/16" across. It looks empty, but it contains the mainspring, along with a mainspring cup and a base pin. If you look at the back of the MSH, you'll see a small hole with a pin in it. This pin holds the mainspring and its accessories down in the hole. This pin needs to be driven out using the 1/16" brass punch. It's tapered, with the wide end at the back, so be sure to drive it from the front to the back. Also, as soon as this pin is clear the mainspring will come flying out, so put something over that hole in the top of the housing. Don't use your finger, because it hurts like a sum*****.

Once the old one has been removed and stripped, test-fit the new housing. It actually slides up into rails in the back of the frame. It should go in fairly easily, and fit flush with the bottom of the frame. You should also be able to easily slide the 1/8" steel punch all the way through the housing and both sides of the frame.

Odds are you won't be able to.

Remove the new housing and take a look at the front of it, near the bottom. There's a raised block that pushes against the frame and provides tension. You'll need to file down this block, a little at a time, until the bottom of the new MSH fits flush with the bottom of the frame and you can slide the steel punch all the way through.

Once that's done, an optional step (if we're talking about a blued MSH and not a stainless one) is to blue the filed-down block at the base of the MSH using a little cold blue. This isn't for cosmetics--it just helps a little with rust prevention.

When that's done, install the base pin, the mainspring, and the spring cup in the new housing. The base pin goes in first, wide end down. The mainspring goes in next, and the cup sits on top of that. Use a punch to compress the mainspring, and tap the tapered retaining pin back in, from back to front.

When you put the new MSH in for the last time, be sure that the hammer strut slides down into the hole that houses the mainspring. Also make sure that the flange at the bottom of the grip safey is covered by the MSH, so that the MSH holds in place. Then tap that first pin back in to hold the housing in place, from right to left.

[Wolfgang]

Are you sure it is from right to left?

[bluewater]

He said that it was from left to right.

;?

[ceemack]

It may be different if your gun has an ambidextrous safety.

[Wolfgang]

Originally posted by bluewater
He said that it was from left to right.

;?

Really?

Then tap that first pin back in to hold the housing in place, from right to left.

[mikep]

This arched MSH will fit without any filing (it was in there before), and the pin from the plastic MSH goes into the metal one. It is definitely a change to change parts on a 1911 after working with a Glock. Protect your eyes, the mainspring is under singificant compression in the housing.

[nickE10mm]

As I understood it, if you tap a pin out from left to right, the re-installation should be the same way. I could very well be wrong. I guess I'm just thinking out loud. :)

[Robert McLeod]

If someone said it somewhere in here I apologize for reposting, but make sure after you field strip your pistol you let the hammer down before you remove the mainspring housing pin. It removes the tension and makes it much easier, as well as preventing damage. Also, do not let the hammer "snap" against the frame, this can cause damage as well, hold your thumb on it and ease it down.

[Kruzr]

The MSH pin drifts from port to starboard......that's left to right when looking from the back of the gun. You drive it out from the dimpled side to the round side of the pin. Replace it from port to starboard again.

[c5367]

Thanks to all who responded for all the helpful tips, I really do appreciate it. I'm going to give it a to try. I think I'll have to pick up the brass punches, though, as I don't have any on hand. Oh darn..... I'll have to buy more tools, how horrible (heavy sarcasm) :)

[ceemack]

Kruzr is right...I misspoke. It needs to go back in from left to right, in the same direction it came out. The peened/rounded end goes in first, and you drive the dimpled end.

[Wolfgang]

Originally posted by nickE10mm
As I understood it, if you tap a pin out from left to right, the re-installation should be the same way. I could very well be wrong. I guess I'm just thinking out loud. :)

I believe you will want the hammer and sear pin to go out right to left, with just a slight push, and back in left to right?

[Kruzr]

The hammer and sear pins will only come out and go in one way. From the port side or left side.

[c5367]

Finally got around to swapping the MSH. It was easier than I expected, thanks in no small part to the tips y'all provided. The arched MSH fits nicely, and helps out the pointing characteristics, for me at least. It points just a touch higher than it did with the flat MSH, which gives me a perfect natural POA.

Thanks again! ;c