How to install post sight?

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I'm building a ca. 1630 snaphaunce gun with a smoothbore octagon to round barrel with a .75 cal bore. One of the two guns I'm basing it on has a front sight I'd like to duplicate--just a little round topped post, about 1/2 inch from the muzzle. The post is no more than 1/8 inch diam. I would assume that I would drill clear through the barrel wall (quite thin here) and sweat-solder the post in place. Is there any safety issue with installing it this way? Any better methods? Never done a little tiny sight like this before.

Dave T.
 

paulvallandigham

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YOU could try grinding or filing a small "flat" on the top of the muzzle. and then using hard silver solder to secure the bead to the barrel that way.

A lot of the older guns have the hole drilled through into the bore, and then filed flush. Epoxy or, on the old guns, some kind of silver solder, or lead solder holds the bead in place.

I have seen threaded holes made in thicker, more modern barrels, but no matter how thick the barrel wall is, there are not very many threads there.
 

Zonie

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IMO, by the time the shot load or the ball gets out to the muzzle, the pressures have dropped off substantially. I wouldn't think a hole thru the barrel wall with a soldered plug in it would cause any problems as long as the end of the plug inside the barrel was flush with the bore.

Just for talking purposes lets say the pressure out there at the muzzle was a totally unrealistic 10,000 PSI. (That's almost twice the pressure Lymans Black Powder Handbook shows for the breech pressure in a 12 guage).

If the post sight was 1/8 inch in diameter it would have a surface area exposed to the bore of .0123 square inches.
That value times 10,000 PSI results in a force of 122.715 pounds trying to blow the sight out of the barrel.

I would not trust a epoxy to do the job of resisting that kind of load but a good low temperature silver bearing solder should be able to hold 123 pounds of force so the plug shouldn't blow out.

If the plug was threaded and screwed in place it would be able to take at least a 300 pound load.

Threads plus solder would be a "Never fail" mode of construction.
 
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Thanks, Paul. I had considered tapping with a 4-40 thread but with barrel thickness of no more than 1/16 inch, I dont know. Maybe thread and solder?
 
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Zonie,
Your post appeared while i was replying to Paul's post (I'm a very slow typer). I think I'll try the "failsafe". Thanks.
Dave T.
 

paulvallandigham

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I think you have to do Both of something. If you thread it, you also have to either epoxy it, or solder it. I cut back some barrels on an old DB shotgun, where one barrel was damaged, but I had the thin center top rib to use to screw in the new bead sight. I did thread the rib, but I also used epoxy on the bead's threaded post. Its been holding now for more than 35 years. Its not subject to the same pressure that a sight drilled into a barrel would be, but those barrels and rib are still vibrating every time the gun is fired. I have always figured that if the epoxy gave out, I could go back and solder the bead in place.
 

bingo1952

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I am assuming you are making the sight youself and if that is the case use a 3-56 thread thread instead of 4-40 with only 2.5 threads. That will give you 3-1/2 threads. Since you are also soldering it should be plenty strong if you don't drop it on a hard object. Pressure at the muzzle is probably down to 20-30% at most from what the maximum breech pressure is.
 

Russ T Frizzen

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Some early guns have the sight set back from the muzzle a few inches--I recall one where the sight was a good five inches back from the muzzle--maybe to give enough thickness to allow a little flat to be filed for the sight to rest on and be soldered to. My fowler has the sight simply soldered to the barrel with no flat at all. It's still there after years of use.
 
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