POSSIBLE GERMAN PRODUCED RIFLE LOCK BOLT DETAILS HI RES PHOTOS ADDED 5/09/23

[WESTbury]

Please see the photo added on 5-01-23 for updates.

The photo below is one that should have been posted with my previous "J GRAEFF" post a week or so ago. It is a dimensional study of the Lock Bolts and highlights an interesting detail relative to those bolts. This is the only German made rifle lock I have ever studied so what I consider an "interesting detail" may be common place and known to all on the ALR who have been students of Original Longrifles for many years.

My novice opinion is that what I have noticed may be a "Foolproof" feature common to these old German locks and nothing unusual at all.

I'm looking forward to the opinons and observations of the ALR Crew.

Kent

[Buck]

Kent,

I have owned a couple of Frederick Sell pieces, 1 pistol and 1 rifle. The same bolt configuration applied. The front bolt was smaller / shorter than the upper. According to one of the foremost authorities in the field he was the only one to do this - a “trademark”. I never examined anything after that discussion to test the theory but it’s interesting to see you’ve encountered  the same condition.

Buck

[rich pierce]

If I’m seeing it right the front one is thicker. I would not expect this because it has to pass through the web between barrel and ramrod.

[Buck]

Rich,

You’re correct. My point was to the difference in size.

Buck

[WESTbury]

Buck, Rich,

My thought is that the person who built the lock, wanted to make sure that the larger dia. screw, which is longer under the head, could not be installed and possibly bind up the lock. What I mean by that is, the threaded end of the screw would contact the hammer before the head bottomed out in the c'bore of the side plate. That's what I refer to as a "foolproof".

Kent

[Bob Roller]

Micrometer and thread gauge will tell what it is and what it ain't.
Bob Roller

[rich pierce]

Buck, Rich,

My thought is that the person who built the lock, wanted to make sure that the larger dia. screw, which is longer under the head, could not be installed and possibly bind up the lock. What I mean by that is, the threaded end of the screw would contact the hammer before the head bottomed out in the c'bore of the side plate. That's what I refer to as a "foolproof".

Kent

Sounds reasonable. But I’ve not seen this as typical on original locks, where the front bolt is thicker than the rear. On some top quality locks the hole in the bolster is a blind hole.

[WESTbury]

Micrometer and thread gauge will tell what it is and what it ain't.
Bob Roller

Good points Bob. However, the threads are certainly not U.S. threads!!

The crests and roots are very wide and the included angles are of course not uniform at all. Some look almost like a trapezoidal thread. You guys are lightyears ahead of me with these rifles. I would suppose that the threads of the screws were generated with a Screw Plate of some type and not single pointed. Chasers were almost 100 years in the future.

Appreciate all of the replies so far, thanks.

[Bob Roller]

The photo below is one that should have been posted with my previous "J GRAEFF" post a week or so ago. It is a dimensional study of the Lock Bolts and highlights an interesting detail relative to those bolts. This is the only German made rifle lock I have ever studied so what I consider an "interesting detail" may be common place and known to all on the ALR who have been students of Original Longrifles for many years.

My novice opinion is that what I have noticed may be a "Foolproof" feature common to these old German locks and nothing unusual at all.

I'm looking forward to the opinons and observations of the ALR Crew.

Kent

The rear screw shows a 1/8x32 which is very close to a modern #5 and a shank near to the modern #8. Looks like a repair that went sour
long ago.The font screw is a modern 10x32.Is that a blind hole in bolster or a all the way through?
Bob Roller

[JTR]

By the looks of them, I would think both of the screws are modern replacements.

The HB initials,,, Henry Bishop,,,,, naw, probably not. I know Henry has been around a while, but probably not that long! 

My Bucks County rifle has a very similar lock, with the initials IB or IR stamped inside.

John

[WESTbury]

By the looks of them, I would think both of the screws are modern replacements.
John

Very possible. The thread forms are ugly though and not uniform as well.

[rlm]

Very possible that at one time the front hole threads were stripped and a larger bolt installed. Threads through the thicker bolster area would be much more durable

[WESTbury]

Very possible that at one time the front hole threads were stripped and a larger bolt installed. Threads through the thicker bolster area would be much more durable

RIM

Thanks for your thoughts.

The tapped hole for the rear lockbolt is in the lockplate. The larger hole is clearance for the rear lockbolt and is in the rear extension arm of the pan as is the case with most locks having detachable iron pans.

The heads of both screws are very uniform with each other in dia and thickness and form. I believe they were both made at the same time, possibly/probably by the person who made the lock.

It would be nice if we actually knew for a fact where and by whom some of these locks, with initials stamped into the interior of the lockplate, were made.

Kent

[WESTbury]

[/quote]
The rear screw shows a 1/8x32 which is very close to a modern #5 and a shank near to the modern #8. Looks like a repair that went sour
long ago.The font screw is a modern 10x32.Is that a blind hole in bolster or a all the way through?
Bob Roller
[/quote]

Bob,
Thanks for your thoughtful analysis.
I have to confess that the measurements I took were quick and dirty using a Machinist Scale. They really were not done with a view to posting them on the ALR. I will have to borrow my brother-in-law's dial caliper and get good measurements on the dia's. I do not know if he has thread gages, but will check, however I suspect that they will not be much help. I measured the threads crest to crest to get a TPI but, the crests are truncated to one degree or another, so it's something of a SWAG.

The threads on these two screws are quite ugly and not fully formed U.S. Threads. Neither the crests/major dia or roots/minor dia are uniform at all. I spent eight years working at Geometric Tool in New Haven in the 70's so I can fairly confidently say that the threads on these screws are not modern quality. They look worse than those I single pointed on a lathe in Shop Class.

Hopefully, I can give you and others cleaner info to work with tomorrow.

Kent

[rich pierce]

Screw plate swaged threads of the period seldom correspond to modern cut threaded standards.

[Bob Roller]

The rear screw shows a 1/8x32 which is very close to a modern #5 and a shank near to the modern #8. Looks like a repair that went sour
long ago.The front screw is a modern 10x32.Is that a blind hole in bolster or a all the way through?
Bob Roller
[/quote]

Bob,
Thanks for your thoughtful analysis.
I have to confess that the measurements I took were quick and dirty using a Machinist Scale. They really were not done with a view to posting them on the ALR. I will have to borrow my brother-in-law's dial caliper and get good measurements on the dia's. I do not know if he has thread gages, but will check, however I suspect that they will not be much help. I measured the threads crest to crest to get a TPI but, the crests are truncated to one degree or another, so it's something of a SWAG.

The threads on these two screws are quite ugly and not fully formed U.S. Threads. Neither the crests/major dia or roots/minor dia are uniform at all. I spent eight years working at Geometric Tool in New Haven in the 70's so I can fairly confidently say that the threads on these screws are not modern quality. They look worse than those I single pointed on a lathe in Shop Class.

Hopefully, I can give you and others cleaner info to work with tomorrow.

Kent
[/quote]

[Bob Roller]

Those screws may well have been single pointed in a High School shop class.The rough cuts can well be from an unsupported shank but that would be unlikely unless extremely light cuts were made.Old screws and the way some were made could be a study I know how I made them but there are others with different ideas and approaches to this.
Bob Roller

[Eric Kettenburg]

I'm not going to 'state' much either way given that I'm just looking at a picture, but the vast majority of American lock bolts that I have seen that are original seem to correspond fairly closely around 3/16X24, which would be also @ 10-24.  Also I have seen them worked out in multiple ways, i.e. some have fairly thin shanks that just barely can accommodate the size of the threads, and others are thicker and tapered down with shanks that are clearly larger than the thread size would dictate.

I don't think I would try to make any kind of generalized assumptions about a lock bolt 'philosophy' of manufacture other than to say that a modern 3/16 X 24 thread is pretty darned close to an awful lot of them.

[Bob Roller]

When I was making locks I made cross screws if requested for $5 each.The 8x32 was the one mostly made and some asked for the 6x32 so
an encounter with the main spring could be avoided,I used 12L14 for all screws no matter what size.
Bob Roller

[WESTbury]

Here is a link to a thread started in 2011 about Screw Plates that has some relevance to this thread.

Some familiar characters from the ALR participated.
 https://americanlongrifles.org/forum/index.php?topic=19172.0

[WESTbury]

See dimensions in BLUE which were determined with a 1" Mike and Screw Pitch Gages.
One can see the fallacy of "eye balling" using a scale and an Eye which was activated in the 1940's.

Both of these Lock Bolts look to have been made from forgings and have the appearance of being threaded with a screw plate. There are no "turning" lines on the shanks as you would expect from a lathe. When they were made is open to question.

[WESTbury]

I am adding Hi Res photos of both lock bolts that look to pretty clearly show(at least to me ) that the threads on these two bolts were generated by a Screw Plate. Also added is the link to a past thread concerning Screw Plates.
Counter arguments are welcome.

https://americanlongrifles.org/forum/index.php?topic=19172.0
 




The bolt shown below is the bolt shown in the above link for comparison of the threads.

[rich pierce]

Agree screw plate. Not sure why anyone would think otherwise. Perhaps someone has found cut threads on guns pre-1800, maybe in military applications, but I am unaware of cut threads in that period.

[WESTbury]

Thanks for your input Rich.

All of the Springfield Armory flint muskets I've examined over the years, have the same type of threads as well. I seem to recall that the museum at the N.P.S. Armory in Springfield has some of tooling and fixturing for the Model 1816,as well as a large case of gaging for the M1816. If I ever get up there again, I'll look to see if they have Screw Plates.

Kent

[JV Puleo]

This is a very interesting discussion and, since screw threads are one of my particular interests, I'll add my two cents.
I am sure those threads were made with a screw plate but I have seen threads on internal lock screws that appear to have been cut...I'm thinking of a British volunteer musket I have in near new condition and, from the proof marks made before 1805 though I confess I have not taken high res photographs  or examined them under extreme magnification. The possibility exists that armory threads, at least, were cut.

In 1798 David Wilkinson (of Pawtucket, RI) patented a screw cutting lathe. It didn't look like our notion of a lathe and was not the first screw cutting lathe but it was fairly successful and a number of them were purchased by the Government. Much later (1831?) Congress voted him a reward of something like $10,000 for his contribution to saving the national armories. Unfortunately, we don't know exactly what the lathe looked like since none have survived and the patent drawing much reproduced is actually a reconstructed copy. The original was destroyed in the Patent Office Fire during the War of 1812.