Good Morning Trey,
For JBMR parts, contact:
Western Gun Parts, Ltd.
17324-106A Ave.
Edmonton, AB T5S 1E6
PHONE (403) 489-5711
FAX (403) 489-5717
If Western is still in busines, they might be able to help you.
At one time they specilized in obsolete parts for discontinued Browning firearms. Back in the late 1980's I managed to buy a JBMR 45 caliber, complete with breech plug, from them, but was informed 54 caliber barrels were no longer available.
I am not aware of any replacement barrels manufactured for thE JBMR. However, any really good gunsmith (centerfire or muzzle loading) should have no trouble removing the breech plug and other components from the original barrel and re-installing them on a new barrel such as a Green Mountain barrel.
There is at least one good muzzle loading gunsmith on this forum who can do this work, but am not sure I can mention his name in this capacity.
This work involves only basic machining procedures. A possibility is to send the JBMR barrel to Track of The Wolf and ask them to re-install all of the parts on a new barrel.
The TOTW people are fine people, carry barrels from a number of makers and do the type of gunsmithsmithing work necessary to install the original parts on a new barrel, as well as sell you a new barrel.
Another possiblity is to send the barrel to:
Robert Hoyt
700 Fairfield Station Rd.
Fairfield, PA.
PHONE: (717) 642 6092
Mr. Hoyt does excellant barrel relining work at a reasonable price.By relining, you will be able to retain the original looks of the entire rifle.
Should you replace the barrel, by all means hold on to the original barrel; it has value.
By the way, TOTW is now selling replacement barrels for the Hawken style Lyman Great Plains Rifle. It is advertised on their website.
Best regards and good shooting,
John L. Hinnant
If you are not an NRA or NMLRA Member, why not? I am carrying your load.