Shiloh Rifle Forums

Recently took delivery of a 1877 and having a problem with mounting a MVA base on the tang. The problem is when the base is mounted on the rifle and torqued to 18 inch pounds I cannot fit the sight to the base. I can loosen the screws enough to allow the sight to fit then retighten the screws however removing the sight the base returns to not allowing the sight to mount without loosening the screws again . I have called Shiloh and was told the base needs shimming ,has this happened to anyone else ? Not sure a about shimming as none of my 74’s required any kind of shimming and never heard of a Shiloh needing to be shimmed while being mounted with MVA anything. Anyone else have this happen ? Should I just take the rifle to Shiloh and let them shim the base and square up the sight ? Base and sight have been back to MVA and they said all is good to go.

I have needed shims to get the sight plumb, but I haven't had it distorted so I couldn't install the sight. This is only when adding sights to rifles myself. When you get Shiloh to install the sight base they custom fit it to the rifle. Those have all been perfect on my rifles.

Chris.

The sight base is hollow ground at a smaller radius than receiver top, so when you tighten the screws there is enough base flex to bring the ears in enough to cause a hard reinstall of staff. Shimming only makes the base lean one way or other and the base flex is will still be there.
kw

Thanks Chris I’ll make another trip to Shiloh and let them do what they do and make it plumb. They did the scope mounts just not ready for a scope ,have the scope but prefer irons for now.

Great explanation KW , definitely going back to Shiloh and let them do it.

My 77 does not have the symptoms you described. Of course, once mounted, I have not dismounted my staff on my 77.

Woody

Woody did you tighten the base screws before mounting the sight and no problem with installing the sight ? Or do you have different method ? Just trying to learn some more about these rifles.

The MVA base for the '77 requires tightening the screws to get the proper tension on the staff spring. It will not stand up straight until the base screws are tight. You should be able to remove the staff without loosening the base screws. I was able to on mine to use a scope.

John gave you the answer. My 77 is not drilled and tapped for a scope, so it wears it's iron continuously.

Woody

I can't tell from your description whether the inability to install the staff is because the staff will not fit between the ears of the base, or whether you are having trouble compressing the detent spring.

No problem with compressing the spring when the sight is less than snug , the problem is there’s enough flex in the base to pull the base ears in and not allow the sight to mount. KW diagnosed the problem.

Sounds like the usual hollow grind done to the reverse side of the base on your sight doesn't match the tang on your '77 well. So the area on the bac of the base around the screw holes is being sucked down too much causing the "ears" on the base to pull closer together.
Only two ways to fix this that I can think of. Either stone the edges of the sight base on each side to eliminate some of the curve, or put a very thin shim washer behind each hole to stop the base from being flexed when tightened down.
It might also work to not put so much force on the screws when tightening them, and use blue Loctite on them to keep them from backing out instead.

Took the drive today to Big Timber and the rifle, 30 min. of their time all is good. They did the front sight as well ( MVA Winchester). Worth the six hour round trip.

Like others told you they would look after you very well you will not find any nicer people to deal with they are great people

I haven’t even brought the hammer back to full cock yet, cleaned the bore and waxed everything . Spring storm tonight though Sat. so just a few more days. .