03A3 Rear sight removal/replacement
Depending on the maker and vintage of your rifle, you may or may not be able to get the old sight off without destroying it.
Initially, the rear sight was intended to be retained by a set screw which was staked to prevent it from loosening. It was found quite early in production that the set screw alone was inadequate to keep the rear sight from moving with the rough handling experienced in military service. The dovetail on the receiver bridge was grooved, and the soft metal of the sight base was staked to upset it into the grooves of the dovetail to supplement the set screw. It appears that Remington in later production did away with the set screw entirely, and relied solely on heavy staking to retain the rear sight. It appears that Smith-Corona retained the set screw to the end of production, but also staked the rear sight base, albeit much more "daintily" than Remington.
The first picture is of a very late Smith-Corona (4,75X,XXX) base, but would also be representative of an early Remington base:
https://www.milsurps.com/images/impo...ightbase-1.jpg
Note the set screw with stake marks (green arrow) and the single light punch mark (red arrow) used to stake the base to the dovetail.
This one was very easy to remove and re-use. It takes some work and patience to move the set screw due to the staking, and you may need to judiciously employ a tiny grinding point on a Dremel tool to weaken the staking, but it will come out with a properly fitting screw driver once the staking is weakened enough. I put a piece of 3/4" steel plate between the "ears" of the base after removing the windage yoke, screw and knob. This prevented the "ears" from bending in while the base was drifted off the dovetail. The plate is shown as the red "block" in the following pic.
https://www.milsurps.com/images/impo..._sight_A-1.jpg
(The line art that I have borrowed here is from the fourth edition of Clark Campbell's excellent book The 03 Springfield Rifles' Era, which belongs in your library if you are a collector, shooter or "student" of the 03A3)
This next pic shows the removed base and the grooved dovetail base on this same rifle:
https://www.milsurps.com/images/impo...eredbase-1.jpg
The reason that I wanted to re-use this base is that I made up a target sight mount using a spare base from Numerich. I can easily remove the "issue" sight, and replace it with the "target sight" when I am not limited by the "as-issued" rules, and replace the issue rear sight for Vintage matches.
https://www.milsurps.com/images/impo...ntedback-1.jpg
https://www.milsurps.com/images/impo...Mounted2-1.jpg
The set screw on the issue sight base retains the issue sight satisfactorily since I don't slam the rifle around or do any bayonet fighting.
The next pic shows the base of a November 1943 Remington rifle.
https://www.milsurps.com/images/impo...ightbase-1.jpg
Note that it is very heavily staked in two places, and there is no set screw at all. It is not likely that this base could be removed without destroying it. In replacing sights so heavily staked as this one, I have found that drilling out the stake marks as much as possible without hitting the receiver bridge dovetail weakens the metal of the base enough so that the base can be drifted off the receiver bridge without excessive force.
When installing a replacement sight, I recommend that you retain the sight with Marine Tex or high strength LocTite rather than staking it. That way, if you need to remove it or adjust it in the future, you can do so without destroying it. If the replacement sight is a little loose on the dovetail, peen the female dovetail of the base slightly so it is snug, but can be drifted with light force. Set the windage on mechanical zero (MZ), and sight in on a calm day at 100 or 200 yards. Center your group by moving the whole sight on the dovetail. When you group is centered laterally mark the rear sight base to match the mark on the receiver. Then turn the rifle on its right side and dribble some LocTite on the joint between the receiver bridge dovetail and sight base. You could even use Super Glue. As long as you're not doing any bayonet fighting, this should be adequate to keep the sight from moving, and your no-wind zero will coincide with the MZ of the sight ... Much easier to remember, and gives you the max amount of adjustment on either side.
Resp'y,
Bob S.
