Author Topic: loose hammer on a J Browning Mountain Rifle (Read 12830 times)

borderdogs · « **on:** February 20, 2014, 05:56:48 PM »

Hello.
I am brand new here and I wanted to post a question and I am not sure this is where to post it. My question is on a newly acquired J Browning Mountain Rifle that has a loose hammer. That is when the hammer is at rest light pressure, like to pull it back to cock, will bring it off the nipple easily. Actually holding the rifle so the hammer is hanging will bring it off the nipple slightly. I know this isn't right but not sure what to do about it.

It's been a while since I messed with percussion rifles and I have never tuned a lock before. But my guess is that there isn't enough spring pressure on the hammer. I haven't taken the lock off yet. Any info would be appreciated.

As by way of introducing myself I am interested in both flint and percussion rifles and pistols from any era. I have recently ordered a Hawken rifle from Brant Selb. I want to try my hand at building one probably a full stock Hawken flint. I have only built one rifle 30 years ago but it was a kit with minimal work to be done. I have been reading the gun building section of the forum and find it very interesting,
Thanks,
Rob

Acer Saccharum · « **Reply #1 on:** February 20, 2014, 06:25:01 PM »

Rob, if you put the lock on HALF-COCK, what is the action of the hammer like? Does it jiggle front-to-back? Or is it solid?

borderdogs · « **Reply #2 on:** February 20, 2014, 08:39:47 PM »

Acer,
Thanks for the quick reply. When the rifle is in half cock it is rock solid..........it is a single set trigger, could that be the issue?
Thanks,
Rob

Acer Saccharum · « **Reply #3 on:** February 20, 2014, 10:20:37 PM »

It sounds like when the hammer is all the way down, the mainspring is no longer pushing on the tumbler. If this is the case, then the hammer can jiggle when all the way down.

This is not healthy, as you'll get blowback when the gun fires. The force of the explosion will lift the hammer off the nipple, causing extra gasses to exit thru the nipple. Also this allows pressure loss, which will affect accuracy on the target.

It sounds like red heat, re-shape, anneal, then harden and temper is in order for your mainspring. Or see if you can get another one.

There are ways the Mainspring can be adjusted, but I'm not qualified to advise you on this. I suggest you search the archives for mainspring treatments.

Dphariss · « **Reply #4 on:** February 20, 2014, 10:29:41 PM »

Not having the lock in hand its impossible to tell.
I would take the lock out of the wood and see how it works. It is possible that their in interference in the lock inlet. In any case its best to have someone with expertise check it out.

Dan

Acer Saccharum · « **Reply #5 on:** February 20, 2014, 10:46:11 PM »

Good thought, Dan. Maybe the mainspring lower leaf is resting on the wood when the hammer is all the way down. Put some black magic marker or Prussian Blue on the spring, put the lock back in the gun, and lower the hammer. Put lock back on half cock, and take the lock out. See if there is any black transferred to the wood.

borderdogs · « **Reply #6 on:** February 21, 2014, 12:08:06 AM »

Thanks for the advise and comments I really appreciate them. I can take the lock out and check it out to see if there is interference. I am a machinst by trade so I can heat treat. anneal, and temper but not sure of the shape the spring would have to be. Is there someone you guys would recommend to check the lock out?

I have been looking for a J Browning Mountain Rifle in iron for a while and when I saw this one I snapped it up. I got it to shoot it so I want it right. The rifle came with another main spring and I haven't really checked it out yet. Could be that is a new replacement spring I will check that out too.
Thanks,
Rob

borderdogs · « **Reply #7 on:** February 22, 2014, 10:30:05 PM »

Okay, I checked the lock and it is the main spring it doesn't have enough tension in the lower leaf. I have a spare spring and it has the same problem. I checked to see about replacements and can't seem to find either the same spring or something similar.

Any ideas on a new spring source?
Thanks,
Rob

T*O*F · « **Reply #8 on:** February 22, 2014, 11:55:07 PM »

A field expedient fix is to make a small wedge from a popsicle stick and insert it enough to spread the leaves apart. I've had a couple of original guns that still had this fix in them.

You can also rework your existing spring to spread the leaves apart just enough to provide some spring tension in the at rest position. Anneal the spring and then spread it slightly while it's still red hot. Then refinish, harden and retemper the spring.

borderdogs · « **Reply #9 on:** February 23, 2014, 04:37:24 PM »

Thanks T*O*F,
To say I am nervous about doing this is putting it lightly. I have heat treated parts before mostly small parts used in molds for plastic molding. Those parts were mostly pins or bushings that I put in a furnace and knew what temperature I was working with.

I have two springs for this rifle but I would hate to break one, and without knowing the right temperature to temper the spring (other than color) I risk breaking it if done wrong.

Here is a link I saw about heat treating & temper:

http://www.ctmuzzleloaders.com/ctml_experiments/tempering/tempering.html

I am not sure of the merit of using s lead pot furnace, I have a set up like that. I guess the other way is to see if there are those out there who would do the job. Any recommendations on someone I could send the springs to who would do this job for a fee?
Thanks,
Rob

Dphariss · « **Reply #10 on:** February 23, 2014, 05:05:15 PM »

Quote from: borderdogs on February 22, 2014, 10:30:05 PM

Okay, I checked the lock and it is the main spring it doesn't have enough tension in the lower leaf. I have a spare spring and it has the same problem. I checked to see about replacements and can't seem to find either the same spring or something similar.

Any ideas on a new spring source?
Thanks,
Rob

Polish the spring to bright. Nothing more than 320 or dull 120 if s belt sander. At least the entire lower leaf.
Clamp in a brass/copper padded vise at the bend. Flex the leaf down with pliers or vise grip at the tip, about 1/2" or a little more should be enough. Now carefully with a moving flame heat with a propane torch so the whole leaf gets to blue at the same time. At this point the pressure needed to spread the spring will go to zero or near it. When it does stop heat immediately. Let cool. this should re-arch the spring.
If not I would harden and temper.
The modern factory mades are generally designed and made by people with only a vague idea of what they are trying to do. As a result the locks and other parts are often lacking in proper function. Since the people making them don't understand proper function.
The percussion lock, if properly made will produce more pressure on the nipple than at full cock. Forsythe called it "the heavy first lifting". Its a geometry thing concerning the tumbler and mainspring that was figured out by lock filers in the 18th c. But like many things from the past its been lost to the industrial revolution and the coming of box lock breech loaders and such.
Re-arching will solve the problem either by the simple method explained here or by a full heat treatment.

Dan

Dphariss · « **Reply #11 on:** February 23, 2014, 05:15:41 PM »

I use a saltpeter (potassium nitrate) bath to draw temper. This can be obtained from places that sell chemicals for making biodiesel from used cooking oil. Heat it till it melts, once solidified into a solid mass heat the edges of the steel pot first since the stuff off gasses oxygen when melted and can build pressure if heated only at the bottom. Dip the polished part, heavy sections first into the melted saltpeter until the color comes to a nice uniform blue (purple/peacock is not hot enough gotta be bright to fading blue) then allow to air cool. Warm water will remove any hardened saltpeter. Let the blue get into grey and the spring will be to soft.
This works with 1080-1095 and O1 and makes a good spring with a nice color. Springs need to be quenched in light oil at 100-120 degree light oil not water.

Dan

D. Taylor Sapergia · « **Reply #12 on:** February 23, 2014, 06:08:22 PM »

I'd like to see a photograph of the inside of your lock. On all of the J. Browning rifles I've seen in the past, the geometry of the mainspring to the tumbler is terrible. There is no pre-load on the mainspring when the lock is at rest, and at full cock, the tension is huge. this is backward to the geometry and function of a well designed lock. This is one of those examples of a modern designer trying to improve an already perfect thing, for whatever reason.
You mentioned that you haven't yet taken off the lock. My advice to you is to remove the lock every time you clean your rifle. The nipple cup in the hammer as well as the throat need to be carefully cleaned to remove the buildup of fowling that accumulates on the hammer each time you fire it. Removing the lock gives you the opportunity to learn how it functions, ensure the screws are not coming loose, and apply lubrication to wear spots. It also gives clear access to the area on the stock under and behind the hammer where fowling accumulates and needs cleaning. So, remove the lock...only one screw on this rifle...and out it comes.

I'd still like to see a picture if you can swing it.

borderdogs · « **Reply #13 on:** February 24, 2014, 02:21:51 AM »

Dan & D.Taylor,
Thanks for the replies. I just purchased the rifle that was why I hadn't disassembled it yet. But I took the lock off and you are right about a poor spring transfer, it just lays on a roller (or bearing-does't look like a bearing) and transfers tension on the flat of the bottom of the spring. It has such low tension that I could actually hand pull it off without a vise. The other spring is just the same.

I wish I could see another JBMR to see if it has the same problem with the main spring. I really like this rifle and I got it to shoot it, I wish there were a drop in replacement lock or maybe a better designed spring that I could rework to fit. I will try to photograph the lock but I am a self confessed computer moron so it usually takes a while for me to figure this stuff out.
Thanks,
Rob

Bob Roller · « **Reply #14 on:** February 24, 2014, 03:54:50 PM »

I have heard in years past of problems with these JBMR locks but never
saw one off the rifle. It sounds like an unconventional design made to
assist short cuts in manufacture.Can a picture be posted of the mechanism?

Bob Roller

borderdogs · « **Reply #15 on:** February 24, 2014, 05:03:11 PM »

Hi Bob,
I think you are right about short cuts in the design. The quality of this rifle is great. It is any wonder why something as important as a main spring would be an aera to consider short cuts.

I will try to post some pictures today, if I can figure out how to do it.
Thanks,
Rob

Acer Saccharum · « **Reply #16 on:** February 24, 2014, 06:22:13 PM »

Don't know if it's a design shortcut. Could be faulty heat treatment or a forming error on the spring.

Some cartridge guns were designed for the hammer to lift off the firing pin. But you don't want that in a percussion system, downward hammer pressure helps prevent blowback.

Bob Roller · « **Reply #17 on:** February 24, 2014, 07:24:49 PM »

Tradition dictates the lock MUST be the one thing to skimp on.
I still have standing orders for change out kits for the Gibbs/Pedersoli
long range muzzle loaders.This is a very fine rifle but some of them had
problems with the lock.The biggest thing was having to pull the hammer
back beyond full cock to get the fly to release. I now have reason to
believe that the later production of these rifle had remedied that flaw.

Bob Roller

D. Taylor Sapergia · « **Reply #18 on:** February 24, 2014, 08:14:58 PM »

Rob, although I still would like to see some images of the internals of the lock, if I remember correctly, the tumbler has an extension to the end of which is attached a roller bearing, similar to the bearing at the end of a frizzen spring on a flintlock. The mainspring rides on this bearing. It should be a simple thing to re-arc the mainspring's lower arm to apply pressure to the tumbler arm at rest. There should be about 1/4" of compression - in other words, the mainspring should extend past the tumbler arms position by 1/4", and need to be compressed to install it. One thing I remember about this rifle, is that the mainspring stack is incredible as the hammer is brought to full cock. It's a flawed design.

Another road to travel, would be to make a new tumbler, with conventional design, and a new mainspring to match, and have a lock that functions happily.

borderdogs · « **Reply #19 on:** February 25, 2014, 06:14:09 PM »

Hi Guys,
I really appreciate all the insights and advise it's a great resource. D.Taylor, you are exactly right about the lock the way you describe it. I took some pictures of the lock and I will try to post them. Looking at that roller bearing I thought I could simply make a larger diameter bearing and see what that does before I work with the springs.

Also, there is a fellow named Earl Kathan who repairs locks and I have been discussing it with him. He is a NH resident like me and lives about 1/2 hour from my door step. He told me he could either rework the springs or reconfigure the lock with a more conventional main spring.

I am going to find out what he thinks about the lock and I will post the results.

thanks,
Rob

Acer Saccharum · « **Reply #20 on:** February 25, 2014, 06:23:36 PM »

Yeah, you know, it sounds like the spring suffers from being over-compressed. A larger wheel would really strain the mainspring at full cock.

Your suggestions, Taylor, show wisdom beyond your years.

D. Taylor Sapergia · « **Reply #21 on:** February 25, 2014, 07:56:38 PM »

Tom, you're a riot!

SR James · « **Reply #22 on:** February 25, 2014, 11:17:22 PM »

This is not the lock in question, but just FYI to illustrate the subject, here is the lock off my BMR. The mainspring has more load at rest than described by the OP, but still has the load stacking as it approaches fullcock. At rest, the load is very light.

Bob Roller · « **Reply #23 on:** February 25, 2014, 11:29:26 PM »

WOW! That is the first one I ever got to see the innards of.
That would require a major remake for sure.

Bob Roller

borderdogs · « **Reply #24 on:** February 26, 2014, 12:14:09 AM »

That is exactly the same lock and the same problem I have been describing. SR James, thanks for the pictures by the way, your pictures came out better than the ones I took.

The guy I have been discussing this lock with here in NH said that it might need to be reworked but I am not sure what that would involve. Bob, if you don't mind me asking, other than the issues with the main spring, just what would be required to rework this lock? I would like to hear that from an expert.
Thanks,
Rob

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Author Topic: loose hammer on a J Browning Mountain Rifle (Read 12830 times)

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