Rear sight base and aperture loose

[USMCNewdog]

Folks,

I tried a search of the forums without luck which really surprised me! I was looking over my M1's, and found two with rattling rear sight apertures and sight bases.

I tried tightening them by tightening the windage screw, but even to the point that it would not allow me to adjust the windage they still rattled. My other three M1's are all tight with slight movement, but these actually rattle when you giggle them!

I disassembbled the one I tried to tighten, but nothing changed. Is this normal and my other's are just snug (I doubt), or could something be worn (not sure what that would be). They are both the type 4 post war rear sights.

Any thoughts or help would be great!!

Mike

Information

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[Bill Hollinger]

How tight does the cover fit?

[USMCNewdog]

Its loose! it also rattles around, none of the others I have move this much! That seems like a good reason for everything to be loose, is this a regular occurance? It seems like you should be able to bend it somewhere to get a tighter fit?

[Bill Hollinger]

Try taking it apart and either replacing the cover or bending it out so that it will fit tight and "snap" into the receiver. That is the only thing I can think of.

[purple]

You need to replace the rear sight cover. Look for a new one with an intact/unworn inner rib. When assembling the rear sight use rifle grease on the inner rib of the sight cover,the foot and teeth of the aperture,and on the interior bearing ways of the base which contact the aperture. Grease is also required on the receiver where the inner faces of the elevation and windage knobs bear and on the axial holes that the windage and elevation knobs pass through. Final grease point is where the bottom of the base bears against the receiver(you can see the finish wear on the bottom of the base). The grease minimizes wear and friction and helps tighten things up a bit.

[Jack Stanley]

After trying to adjust or replacing the cover , you could try fitting parts my measuring tolerances to get a better fit . Expensive proposition unless you happen to have a couple handfull of part to choose from . Switching to a lockbar type sight might help , but if you tightened down the one you have it's unlikely .

I had a couple sight parts that refused to work together so I encouraged them with a torch . Disassembled the sight , heated the sight base to very dull red while in shaded garage , insert aperature with pliers , gently squeeze sight base with vise , drop in oil to cool .

I actually had to work one of them dry untill it loosened up some . After "adjusting" , I cleaned then real well and regreased before assembling onto the rifle . There was no more wiggle at all .

Jack

[USMCNewdog]

A little followup on this, I had two M1's with loose rear sites, and I took them both to the ran yesterday.

The one rifle was easily sited in at 50 then to 100 yards with good groups! Now the other rifle on the other hand would not group, and even after moving the windage all the way to the right the rounds were still impacting to the left of the bullseye! Very interesting indeed I thought, so Where would you suggest I buy new rear site covers? I am interested in maintaining the rifles in their current condition, but I do shoot them

[OlManDow]

You were on the right track tightening up the tension screw in the windage knob, and the advice on the cover is right on. Due to manufacturing tolerances, there can still be quite a bit of lateral slop in the fit of the aperture to the rear sight base,

Run the aperture up about 20 clicks, then push forward on the aperture with your thumb - it should move against the spring pressure of the cover, and move right back when you release the thumb pressure. If not, it is a rear sight cover issue. Then push the aperture back and forth sideways - if it has significant movement, the aperture is loose in the sight base. There is a tool made to peen the side of the base right in line with the tracks for the aperture to take up that slack. I think Brownells carries it. Else send it to me and I can peen it for you.

OlManDow

eressure, and lunder o merackere

[Bill Hollinger]

As far as the other rifle shooting far left, check the barrel indexing. Also check the gas cylinder fit and front sight. It sounds as though the barrel is not indexed. In other words the barrel is not in line with the receiver. Has the barrel been changed? If so, were the right tools used to align it?

[JBS]

“far left” you did not say what the position of the front sight was on this rifle. Before going to deep into indexing the barrel check the position of the front sight. It is driftable, see if it is far right. If so loosen the Allen bolt and center it and try again. When adjusting a front sight always chase the bullet hole. When you zero a M1, M1A, M14 you center rear sight and correct impact by drifting front sight left or right. That way you have full windage left and right on rear sight.