breech plug for large barrel

[zimmerstutzen]

I have some really large muzzleloading rifle barrels.  1.25 and 1.375 across the flats.  (50 to 69 caliber)   I'd like to make a copy of an original "fat" gun that I already own.  Will I have to get a breech plug machined, or is there a way to make one with out all the fancy machinery. Maybe fit a plug of threaded stock and then weld a tang to the ther end of the threaded stock.

[Blacksmoke]

zimmerstuutzen:   This is the way I do it;  I obtain a large piece of round stock which is large enough in dia. to overlap the corners of the octagon. Cut it  to length.   Then I have  the male threads turned on a lathe to fit the female threads of the barrel.   Screw in the male plug till both the inside shoulder and the  outside shoulder meet.   Make sure it nis tight.      Next comes the file and hacksaw.  First I will file a flat on the round piece to correspond to the top flat of the barrel.  Then I do the same for the bottom flat.  Next I will scribe on the profile of the tang that I want on the top flat  and on the bottom I do the same for the bottom of the plug bolster.   Then comes the hacksaw to cut away the parts of the round that I do not want.  The whole process takes the better part of one day and some elbow grease.  But no fancy machining.      Hugh Toenjes

[Dphariss]

I have some really large muzzleloading rifle barrels.  1.25 and 1.375 across the flats.  (50 to 69 caliber)   I'd like to make a copy of an original "fat" gun that I already own.  Will I have to get a breech plug machined, or is there a way to make one with out all the fancy machinery. Maybe fit a plug of threaded stock and then weld a tang to the ther end of the threaded stock.

Buy a grade 8 or grade 5 bolt 1" is long enough. Fit to the interior shoulder till the bore is sealed and the bolt head touches the breech of the barrel when turned up to 40-60 ft pounds.
Mark the top flat and remove the plug and hack saw the excess from the bolt head making a flat to index a tang too. On large barrels you can tap for 7/8 bolt, even coarse thread and have a larger head to work with.
Weld the tang so it can be shaped to match the top flat. Leave enough that it can be fit tight to the rear of the barrel.
Now ANNEAL THE BOLT and weld. Bolts grade 5 and up may develop hard spots at the weld and then need to be normalized I would heat to red and then let it cool covered with dry wood ash or some other insulator.
Final fit the tang.
If you have a lathe making one from annealed round or barstock is an easy option as well
Dan