View Full Version : How do i install a rear sight on a 1911?

March 10, 2008, 12:39 AM
Getting a colt 1991 and wanting to replace the rear sight with a G.i sight. the sight on it now is a target sight. how would i go about this? or what would i need? also if anyone knows, how do i switch out mainspring housings? as i have an arched housing i'd like to replace with a flat.

March 10, 2008, 08:23 AM
Start with a Kuhnhausen manual, available from www.brownells.com

March 10, 2008, 08:38 AM
When you say, "target sight," what exactly is the rear sight?

Before working on the pistol, remove the magazine. Be sure it's removed. Cycle the slide and lock it back. Confirm visually and by inserting your finger that the chamber is empty and the magazine well clear. Control the slide while releasing it to move forward.

If the rear sight is mounted on the slide in a standard rear dovetail, the procedure is simply to push the old sight off and the new sight on. This is best done with a sight pusher; in the bad old days we used a brass punch and hammer, but the possibilities of damage are greater than with a sight pusher. You should confirm that the rear sight does not have an elevation adjustment screw or some kind of locking screw engaging the dovetail.

A picture would really help.

To remove the mainspring housing, examine the pin that passes through the bottom rear of the frame. This is the pin that retains the mainspring housing. One end will appear concave, the other, convex. Be certain that the hammer is fully down; this will minimize the tension on the mainspring. Push the pin out by pusing on the concave end. This may take some force. I find that sometimes a brass punch and hammer help.

With the pin removed, the mainspring housing will generally pop downwards a bit under the residual tension of the mainspring. Slide it down and completely off. Replacement is simply reversing these steps, with three caveats:

1. Make certain that the hammer strut is properly engaged in the concave center of the mainspring plunger, at the top of the mainspring housing.

2. Make certain that the sear spring, the flat spring with three (or four, in the case of certain custom springs) arms is properly seated in the frame. There is a flange, or tongue, on the bottom of the spring that must engage its corresponding slot in the frame. If the tongue is not properly engaged, it can still be possible to slide the mainspring housing back into position. However, the lockworks will start acting very strangely. You need not enquire as to how I know this :D .

3. You will have to apply some force to the bottom of the mainspring housing in order to get the pin started through it. You'll be pushing on the concave end so that the convex end can more easily get past the point of the mainspring retainer pin.



March 10, 2008, 12:49 PM
It can help, when swapping the mainspring housing, to wrap a rubber band around the grip safety, to hold it in the "off" position, as that will keep the sear spring in the proper orientation while the MSH is removed. If you have difficuly getting the MSH fully re-installed - it won't go the last 1/4" - the hammer strut is not properly aligned with the bore of the housing, and is hung-up on the edge. The housing won't slide completely into place unless the strut is properly positioned to depress the spring.