rear sight problem

[bore_butter]

this is the first time i've asked any questions, usually i glean enough info to solve any problems by reading all the other posts.
my wife bought me a thompson center 36 cal. seneca back in 1974 for my birthday and it more than shoots well. i've always shot 60grns fffg and round ball hornady
ammo.
with everybody shooting lower powder loads, i thought i'd give the 30grn. a try in this rifle. it shoots 2 inches left of center with that load and the same patch .010 lubed.
the rear sight has only been adjusted vertical or lowered and the windage has never been touched or needed any adjustment.
that windage screw won't budge. i've soaked it in penetrating solution for 8 hours and heated it with a hot air blower but it is firmly planted for some reason. there is no rusting anywhere on the sight. i tried tapping lightly with a brass rod and still nothing moves. i don't want to bugger up the screw slot and i'm open to any suggestions.

 

[azmntman]

Look for a replacement. Once found force that booger after explaining to it in detail how you will just buy a new one and carry on if it remains stuborn :hmm:

 

[bore_butter]

I've tried that talking to it and still no cooperation. I've been prying and heating and soaking since 5:00am and nothing is happening but frustration.
I may just head for the local gun smith this afternoon. parts for that Seneca seem hard to find and I don't want to damage what I have.
been looking at getting a rear peep sight for it because I just installed one from lyman on my .50 tc hawken. I however haven't seen one listed for the seneca

 

[don hepler]

You could try Kroil oil, or other oil with penetrating qualities.

I have a 36 Seneca, and shoot 25-30 grains of Black MZ in mine. Very accurate, little rifle. Over loading these little rifles, can cause stocks to crack.

I don't think a gun smith would charge much and like you say, parts are hard to come by.

 

[bore_butter]

after taking a breakfast break I finally got the screw to turn. it was back and forth for quite a while but it is working now. the heat gun cooked the finish a bit but all seems to be fine now.
kroil was what I had it in all that time. it's good stuff. been using that on motorcycle parts for some time now.

 

[Mean Gene]

I don't want this to sound like a dumb question but maybe the screw is already maxed out is why it won't turn.

 

[bore_butter]

the screw was dead center. it runs about 3/32 both directions.
can't go shoot the rifle till it quits raining here.

 

[Cowboy]

A little Perma Blue will fix up the finish on the screw head in a jiffy! Use some 0000 steel wool to buff it up a little. Apply a light swipe of the Perma Blue on the end of a Q-tip. About 60 seconds later another swipe with another Q-tip wet with water to neutralize the Perma Blue. Wipe screw head off and apply a little oil to it to cure the new finish. Wipe the excess oil off in about 12 to 24 hours.

You're now good to go! You probably know how to apply cold bluing already but I thought I'd add the above if it would be helpful to you. If not, maybe someone else would benefit?

Anyway, I'm glad you got the screw loose without buggering up the screw head!

Respectfully, Cowboy :thumbsup:

 

[bore_butter]

when I got the sight back on the rifle I put some baracade on the sight and it all looks like it did before. happy about that one.

it didn't rain so I went to the range with the 36 and got it zero'd in perfect with the 30 grn. load.
the only problem was that when I left the range I accidently left my prescription glasses on one of the gun benches and had to drive back the 39 miles to the range and it was gone when I got there. that makes it a grand total of $300 to fix my little problem today.

 

[Col. Batguano]

the thing that will break screws loose even better is a 50:50 mix of automatic transmission fluid and acetone. I can't recall the figures, but I want to say about a 30% reduction in force from Kroil, and that stuff is pretty good.

 

[bore_butter]

from what I've read about that mix of the atf & acetone is a 50/50 mix. it's supposed to be better than kroil and real cheap to make if you have it just laying around. I've also read that you should use ford atf and stay away from the dextrose type.

 

[ike]

I have one. If you look at the sight it will lift up. You will not see this until you lift it up. There is a very small Allen screw that will tighten on the left/right adjustment. Loosen that screw adjust the sight as needed and tighten that screw again. I had to learn this the hard way like you. You will have a devil of a time finding a replacement sight. I hope this helps.

 

[azmntman]

when I got the sight back on the rifle I put some baracade on the sight and it all looks like it did before. happy about that one.

it didn't rain so I went to the range with the 36 and got it zero'd in perfect with the 30 grn. load.
the only problem was that when I left the range I accidently left my prescription glasses on one of the gun benches and had to drive back the 39 miles to the range and it was gone when I got there. that makes it a grand total of $300 to fix my little problem today.

ff but put an add in craigs list. Good chance you'll get em back :idunno:

 

[Clovis]

I think you are right Ike. I remember a small screw on these sights for locking the setting.

 

[ZUG]

when I got the sight back on the rifle I put some baracade on the sight and it all looks like it did before. happy about that one.

it didn't rain so I went to the range with the 36 and got it zero'd in perfect with the 30 grn. load.
the only problem was that when I left the range I accidently left my prescription glasses on one of the gun benches and had to drive back the 39 miles to the range and it was gone when I got there. that makes it a grand total of $300 to fix my little problem today.

ff but put an add in craigs list. Good chance you'll get em back :idunno:

I think who ever picked up your glasses did so to have them not get lost and if you make a sign up - "left glasses on shooting bench, call XXX - please return" you will get them back. I can't believe someone would be able to use your prescription -- or maybe not!

 

[Col. Batguano]

You'll get them back. I've gotten lots of (expensive) stuff back I've been stupid enough to forget in places.

I had my dog jump out of the car at a gas station once. I was 60 miles down the road before I realized he was missing. The story had a happy ending though. The station attendants put him in a kennel and he was there when I got back there. Tougher to sneak a substitute in the back door than dead gold fish that's for sure

 

[don hepler]

You might offer a reward, for the glasses.

Just thinking.

 

[bore_butter]

my ol reminded me that it's only month and a half till the next eye exam and I should just suck it up and don't do it again.
some days it doesn't pay to get out of bed.

 

[Zonie]

I have one. If you look at the sight it will lift up. You will not see this until you lift it up. There is a very small Allen screw that will tighten on the left/right adjustment. Loosen that screw adjust the sight as needed and tighten that screw again. I had to learn this the hard way like you. You will have a devil of a time finding a replacement sight. I hope this helps.

I figured your post was worth quoting in case someone missed it.

In the 1962 Thompson Center owners manual on page 68 it shows a drawing of a TC sight with an arrow pointing to a very small set screw.
The screw is drawn on the front of the sight next to the windage adjustment screw head.

Quoting the instructions,

"Some models are equipped with a "positive lock" Allen set screw on the windage adjustment (see illustration below). This set must be loosened before you make a windage adjustment and retightened after the adjustment is made."