What’s the general opinion of these Browning muzzle loaders? Can they still be found?

Funny, I’ve been looking for one the last couple weeks. Haven’t found anything on-line yet.

They were excellent rifles but for their triggers which are very probe to break springs. No parts are available to repair them so any repairs have to be done by either replacing the whole triggers mechanism or hand making new springs but do to the design and the limits of the space the springs fit into a new spring is as likely to break as the old factory spring was.

The locks and the barrels were very good however as was the fitting of the parts to the stock.
So if a JB Mountain rifles is like new and you want to keep it that way it's best not to use it at all. If it's a bit 'worn" with a good bore I might recommend you simply have the trigger replaced (or do it yourself) as soon as you get it so you have a good reliable gun.

What trigger would be a good replacement?

A good dst. The single set on mine wouldn't stay in adjustment. Biggest mistake of my black powder life was selling my JB fifty. Paid $300. Would have to go custom build to equal it.

Desirable rifles if you can find one in good condition.

"What trigger would be a good replacement?"

Any regular single trigger. The lock is of high quality so it' is easy enough to tune it for a good light pull.
It may be possible to replace the factory trigger with a set of Davis double set triggers also, but I can't say for sure what would be involved. In some cases you need to make a walnut plug for the old mortis and then inlet a new trigger over the patch, but having not done it myself in that particular rifle I can't say for sure.

Of you can make a new plate from steel and install a hand made single trigger so it looks very professional and yet you can then keep the original as it came so the collectors value is not diminished at all.

One can be found in my safe. Mine’s a 54, which is fairly uncommon. I’ll take it deer hunting next weekend. I think they are first rate. I’ve seen them for sale online from time to time.

Seen two last month at an estate sale, one sold for $750 the other $850. Lock springs are the problem, better know a good gunsmith if you buy one. No spare parts out there.

Don't drop one of those brass bore lights in the barrel they have a tapered powder chamber and the bore light will stock then you have to.pull the nipple put in powder and shoot it out...mb

I would say there are better options.

Buy a $100 borescope on Amazon. Works great,

Long ago, in a galaxy far away, I had an Ithaca .50 half-stock mountain rifle and a buddy had a Browning. We argued constantly over whose gun was better - sights, triggers, accuracy, etc. And then one day his trigger spring broke, and I won!

I had a later Ithaca Navy Hawken. IIRC it came in a Uberti box. It was nice but I think the earlier ones were the true jewels. I shot a doe today with my Browning .54. One ball through the chest with predictable results. Except that in her 50yd death run she splashed into the creek and I had to drag her out. Her last act of defiance.

Yeah, the early Ithacas that were built when using up the remaining stocks of parts from Cherry Corners after the acquisition were the better ones, IMO. It's what mine was. (Said parts can be identified by the tiny stamped cluster of cherries found on discrete locations.) I think I killed more deer with that rifle than any other single gun that filtered through my grubby mitts. Most accurate load: 50gr. Goex FFFg, .490 patched round ball, .015" pillow ticking patch. One hole clusters were the norm at 50 yards. I called it my 50/50 Gun (caliber/powder), and that light-ish load killed with alacrity too - always made me chuckle when I'd hear guys bragging about their fearsome 100+ gain loads with big honking bullets being ideal for whacking deer.

I shoulda never sold that gun, but like everything else in my life I got bored/tired of it.

One quick story: As the sun came up on a ML deer season morning, a stranger stomped into view and sat down about 50 yards from me, despite his seeing me (and my bright flashlight). Feeling righteously p*ssed off I was gathering myself up to vamoose when I noticed a deer moving about 50 yards in front of and below the guy, maybe 80 yards total distance from me. I put the sights on it and Old 50/50 barked and the deer dropped right there. (I don't remember, but I must've scored a central nervous system hit.) The interloper didn't even have the common decency to help me drag it back up the hill......

I was looking for a browning ,ran into a custom Hawken , Bill large match barrel, Roller trigger, curley maple stock, had it for a while haven't shot it, so I guess i'll sell it sometime.

one at auction on proxibid