Poorly Assembled Brown Bess Lock

It’s been a few years since I’ve started assembling locks from castings set, I’ve moved forward with advice and guidance from other gunmakers and have started forging my own springs and scratching making parts and have been assembling and fixing locks for folks.

I’ve assembled and repaired many brown bess locks, Rifle shoppe, Indian, Pedersoli’s, miroku etc.

Brown Bess locks in my opinion, are of the easier locks to assemble with the 1728 being the hardest due to the single bridle pan.

This 1724 Brown Bess Lock was sent to me recently and was assembled very poorly, so poor that the lock does not hold on halfcock.

Interesting Enough the Tumbler’s halfcock notch was ground away and the full cock notch replaced it with a new full cock notch about 2mm absolve it, i can only assume this was done to increase the lock’s energy due to a lame mainspring that was over stoned.

The frizzen is located and drilled very poorly.

The Bridle wasn’t located correctly, an attempt was made to try to offset the screw holes with need files, not a good idea, best to weld up the holes are start over.

The sear screw was grilled about 3mm too high, which is a head scratcher for me because it the easiest screw to locate in the project, it’s marked by the engravings…. It goes here !

The tumbler arbor as also over filed making the flintcock very unstable, an attempt was made by peening the edges for a tighter fit. Best fix is to drop a small bead or two in the flintcock and start over from scratch and refit.

Sear spring was located too high by about 2mm.

Frizzen screw was not shouldered to the plate leaving a significant gap between the frizzen cover and pan (also not shimmed before drilling the tap).

Oddly the pan and bolster has a weld around it, so I’m assuming the person who assembled the lock has the ability to weld, but chose to not correct significant mistakes.

Lots of welding repairs and new casting parts needed.

Video attachment.

Very interesting post . Beautiful lock , I hope you get it all squared away

Sad “workmanship” until it got into your hands.

What a disaster. Why do people throw their money away on such scrap?

Looks like a bit of a mash .
Also Surprised to see you releasing the cock with an open frizzen.

Sounds like an Indian lock.
I don’t think they let the kids that build them have squares.

BadDaditood said:

Sounds like an Indian lock.
I don’t think they let the kids that build them have squares.

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Got to defend the Indians here. I have a loyalist Arms musket , it sparks like the forth of July and compares to Land R or Davis very well

I’ve heard good things about Loyalist Arms Quality Control
The outfit I bought from has no QC
I had to do almost everything the OP (and Mr Person) did on his Indian locks.
Works great now, but I coulda built 2 or 3 Kiblers in the time it took ;-)

FlinterNick did you make your replacement screws or just buy them? I need to make some screws that I can't find a die for - specifically a die for a metric screw with a diameter of 4.5 -1.0 pitch any help?

ZUG said:

FlinterNick did you make your replacement screws or just buy them? I need to make some screws that I can't find a die for - specifically a die for a metric screw with a diameter of 4.5 -1.0 pitch any help?

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Hi Zug

I do make my own screws, however i do use some blank screws from Brownells that work very well.

Use mild steel or sometimes I use 4130 steel which is a little harder than needed but readily available in dowel form.

Certain pivot screws i make myself, like frizzen screws and sear screws. I like having the shaft a little bigger than the threaded end, so i can counter and shoulder them to the lock plates, that way they don’t turn when the parts move.

Thanks for your reply FlinterNick. I found a way to make my needed screws (frizzen and sear) using my lathe and a 10-24 die. My lathe does not do metric threads - older Jet lathe.

ZUG said:

Thanks for your reply FlinterNick. I found a way to make my needed screws (frizzen and sear) using my lathe and a 10-24 die. My lathe does not do metric threads - older Jet lathe.

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I use a hand die for metric screws, i have metric gears too but prefer the hand die.

I use mostly imperial SAE tap and dies but do have a good selection of metric tap and dies. The metric screws that I need have an odd-ball pitch for its diameter which were cut on - I believe - a lathe. I cut 10-24 threads on a shank of 0.020" undersize 0.190" 1018 steel rod and the screw threads nicely into the lock plate. It holds quite well when tighten to "snug" which is enough for this application.

ZUG said:

I use mostly imperial SAE tap and dies but do have a good selection of metric tap and dies. The metric screws that I need have an odd-ball pitch for its diameter which were cut on - I believe - a lathe. I cut 10-24 threads on a shank of 0.020" undersize 0.190" 1018 steel rod and the screw threads nicely into the lock plate. It holds quite well when tighten to "snug" which is enough for this application.

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One thing i do try to do is match the steel grades of the screws to the plates, tough do do but 12L13 or 14 for screws is terrible.

For those who may want to build locks from sets of castings taken off original locks, from TRS or other suppliers (not referring to Chambers kits), I’ve encountered the following issues. I’m not complaining- fixing these is easier than a scratch build by far, but it’s good to know what you may be getting into.

The tumbler axles may not be true to each other or of a diameter that proves useful. For example on a recent build it seems likely they meant the axle going through the lock plate to be 7/16”. But it was already undersized and needed truing up. So now I have to decide what diameter to shoot for where I have a drill for it and have not compromised the square for affixing the cock. Same for the bridle side.

Not all holes that need to be drilled are adequately spotted. Sometimes not spotted at all. Not joking. Sometimes if I drill where they are spotted, the lock won’t work. Example, the mainspring pin. You’ll need to figure out how to fit the mainspring so it’s end is at the tumbler axle at full cock, the toe of the tumbler doesn’t hang up in the hook at full cock, and the mainspring doesn’t fall off the tumbler toe at the fired position.

The cock/tumbler/rest spot on the top of the lock plate may not be timed right. I don’t want the cock hitting the plate waaay back at full cock. I want the cock to stop on the rest on the top of the plate before the lower jaw slams the fence or the stop in the tumbler contacts the bridle stop. I may have to change the half and full cock notches a smidgeon. I may have to add steel to the full rest, fired stop on the cock. Worst case I may have to change the angle of the square hole in the cock.

The screw sets will be generic and will need tuning or replacement as others noted above. We could hope for screws with the right amount of threads, especially for the sear axle so you can’t over-tighten but you’ll have to make one if that’s what you want.

The frizzen won’t get hard enough and will need a sole or deep pack case hardening. This is almost universal.

The slot for the sear spring tab may be off.

The frizzen spring may need arms spread a bit to provide enough force.

The lock plate may be warped. Make sure it’s not hard and straighten it with a copper hammer.
I think all these issues arise from taking castings directly from original locks without compensating for west on the original, shrinkage and cleanup of castings, and so on. Some parts sets give few issues. Others, it pays to really see how things are going to work before drilling and tapping the holes.

I made two of the screws that I needed this morning and they fit well ( 0.0015" all around sear and frizzen). I can case harden them if need be but I will leave them be for now. The tumbler is next when I get the material in. As you can see the original tumbler is 0.350" in diameter and the lock plate is 0.3750" - 0.3765" in diameter. I have a 0.3760reamer so I will ream the lock plate to this dimension and fit the tumbler to the lock plate. I may need to bush the bridle if the tumbler's shaft is off axis centerline - we will see when the time comes.

Very useful stuff, keep it coming. Between this thread and others by Dave Person, there’s a lot of great information here.

I got the 1144 Stressproof steel yesterday and it is a BIG and HEAVY hunk of round stock. I started on rough turning the tumbler this morning. I had to stop by noon time because we are having a wee bit of hot weather here today and I don't do well when the temps are in the high 90's and no AC in the garage (shop). I don't normally turn material over 1" and this 12" X 1-1/2" hunk of steel rotating at a fair RPM is a bit daunting to say the least. I do like turning this 1144 Stressproof steel it cuts like butter with either HSS or carbide too bits. Here are some pictures of what the rough dimensions are at the moment. Most of the dimensions are about 0.030" oversized except for the cock shaft which is 0.004" larger than the rearmed tumbler hole. I will bring all surfaces down to final dimension in a day or two once I do my final calculations.

ZUG said:

I got the 1144 Stressproof steel yesterday and it is a BIG and HEAVY hunk of round stock. I started on rough turning the tumbler this morning. I had to stop by noon time because we are having a wee bit of hot weather here today and I don't do well when the temps are in the high 90's and no AC in the garage (shop). I don't normally turn material over 1" and this 12" X 1-1/2" hunk of steel rotating at a fair RPM is a bit daunting to say the least. I do like turning this 1144 Stressproof steel it cuts like butter with either HSS or carbide too bits. Here are some pictures of what the rough dimensions are at the moment. Most of the dimensions are about 0.030" oversized except for the cock shaft which is 0.004" larger than the rearmed tumbler hole. I will bring all surfaces down to final dimension in a day or two once I do my final calculations.
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ZUG said:

I made two of the screws that I needed this morning and they fit well ( 0.0015" all around sear and frizzen). I can case harden them if need be but I will leave them be for now. The tumbler is next when I get the material in. As you can see the original tumbler is 0.350" in diameter and the lock plate is 0.3750" - 0.3765" in diameter. I have a 0.3760reamer so I will ream the lock plate to this dimension and fit the tumbler to the lock plate. I may need to bush the bridle if the tumbler's shaft is off axis centerline - we will see when the time comes.
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Hi Ya

Youre doing everything correctly here !

And great job on the screw the only thing i do differently in this situation with Indian Locks is I make sure that screws are counter sunk to the tumbler by leaving a small chamfer on the shaft beneath the head of the screw, this keeps the parts from slipping, I’ll see if I can find an example, but lately I’ve been turning away Indian made locks, i just have too many rifle shoppe kits too assemble.

Indian made locks are full of inconsistent geometric issues, all starting with the shape of the flintcock and location of the bridle.

Personally If I were an Indian made dealer I woudln’t assemble these locks, I’d send them to the USA to be assembled with templates, their quality control would increase, a prices would increase slightly.