Lock Screws

[frogwalking]

For most of my life with muzzleloading firearms, I have been used to seeing lock retaining screws with large, cylindrical heads.  These seemed to be the norm, until a half dozen years ago, when large, domed screws seemed to take over.  Is my observation correct, or just a happenstance.  If it is, why has this happened?

Just wondered.

[Acer Saccharum]

It's just a fad. Screwheads come and go into fashion and out.

I really don't have a better explanation than that.

[whetrock]

I wonder if Hershel House's video and his classes may have had a big part in shaping a lot of contemporary builders thoughts on what they are supposed to do. His video shows him making domed headed bolts out of hardware variety carriage bolts, which he turns down to the size he wants.

As you know, the antiques show a lot of variety in shape and size of the bolt heads.

[Mark Elliott]

There is a better reason.   Most of the lock nails or screws on originals, at least in the 18th century,  were large (3/8-7/16") and domed.    You don't start seeing cylindrical head screws until the 19th century,  when most of them were probably machine made.   The better builders who made their own screws have been using the large round screws for some time.   

[whetrock]

So, if I understand you, Mark, you are suggesting that contemporary builders have just begun moving toward a more historically correct design.

Let's hope this is the case. It's a matter of preference, of course.  But I'm in favor of a movement toward the historical flintlock.

[Acer Saccharum]

I make my own. Cut the slots with a 'screw slotting file' mounted in a jeweler's saw frame.

[Pete G.]

I think the cylinder headed screws are from the machine made blanks. A quick perusal through RCA shows that most, if not all of the lock screws are some form of round headed.

[whetrock]

I've been making my own, as well. It would be easy enough to round up a cylindrical head, but the lock screws sold by suppliers I have dealt with already have the slots cut. If I make my own, I can cut the slots as I want them.
I first cut them with a hacksaw that I have ground down (so at so remove all offset and reduce the width of the kerf), then I clean it up with an very narrow triangular file (a "screw slot file" as Acer calls his). Mine is one I made from a fine cut 4" Nicholson mill bastard file that I carefully ground down so as to make a very narrow triangular file. I ground both edges. Here are some photos. The first shows the fine cut that a hacksaw can make if you grind away the offset from the teeth. The second shows a screw that has had the slot cleaned up. (It has also been polished slightly with a bit of 320 grit paper.) It has a slight taper as it deepens. That taper is the difference between a slot that has been sawed and one that has been filed.  (Most modern screws have a wider slot, cut by a small circular saw that leaves a concave groove in the bottom.) (Are we being picky here, or what???   )
The last photo is to show the back side of the file, to show how it is ground from both edges and "blind" (no teeth) on the back side. It is .02 at the edge and tapers back to .05 at the center. A little lubrication helps keep it from binding as you file. Works well for me when used in conjunction with the hacksaw. I can easily "move" the slot to the left or right as needed as I use the file to clean up the slot made with the hacksaw. Having the back side of it blind gives complete control on where it cuts.
I'm not a pro by any means, but this seems to work for me.

(Note: As I made it, the file has teeth on one side and both edges, but not on the back.)

[Don Getz]

I like lock bolts with a round head, like the ones that Acer shows.   I don't really care for the ones that Whetrock shows, these
kind of remind me of a foregrip portion of a stock that has the corners rounded off but are flat on the sides and bottom.   I
have found that you can buy lock bolts with a nice round head, some about 3/8" and some with 1/2" diameter, I personally
like the bigger ones........Don

[Acer Saccharum]

Brownell's sells screw slotting files, I think. Like a flat file, with teeth only on the edge. Available in different widths, specified in tenths of a millimeter.

[whetrock]

Yeah, as Don correctly notes, the screws I showed were not completely domed.  I should have explained that. The edges on these are just as Don describes them, and they would not be appropriate for many of the PA rifles (as Shumway documents in RCA).   These were made for a North Carolina style rifle, based on one from Bill Ivey's book.

As Pete G. noted, most of the screws in RCA are domed. Many are completely domed, leaving only a fine edge. The screws Acer shows are of that type.  Perhaps there was more variation in Southern Rifles. I can't speak about that with any authority, since my opinion about it only comes from the books I have collected. But I do notice more variation in Southern antique rifles. Some are completely domed, some partially domed, some fully cyclindrical, some cylindrical with beveled edges.

It doesn't seem to just be a matter of age, either. The picture below is of the screws from an iron mounted rifle assumed to have been built in VA the late 1700s. Note that they have a double bevel (so that they are hexagonal in cross section). It is a shape that most guys would not find appealing. I don't think it is especially appealing, either, but if I was going to build a reproduction based on this rifle, I would keep with this shape of screw head. Its all a matter of preference. For me the screws are like the hubcaps on an antique car. I think it works best if they match the build.

(It's also interesting that the slots on these screws seem to have been only sawed, and not filed.)

[Acer Saccharum]

That's an interesting head shape. It would fit nicely in a slightly counterbored sideplate.  I counterbore the sideplate  when my lock screws angle thru the stock. Else the heads won't sit level on the plate.

[whetrock]

Yeah, this would have worked well countersunk. But the guy didn't do it. It wasn't for lack of skill, either. The rifle shows excellent craftsmanship and attention to detail.

I would guess that for some guys all this talk about screw heads and screw slots seems like overkill. (It certainly has nothing to do with the functionality of the firearm.) For me, when it gets to this kind of detail it's about art, about pondering how the masters achieved their goal. I enjoy the little details. But to each his own. There's certainly no rule that says it has to be done this way or that!

[Acer Saccharum]

Detail that goes into a gun is not accidental to me. All the little pieces combine into one object, not separate parts thrown together. Every cut, whorl, line, screw, curve, flat, is thought about and choices are made in the process of building. The end result is in mind, and choices are made to move the project in that direction. Then Serendipity enters the stage, and one has to consider her whims......

On the double bevel screw heads, I did not mean to imply that the maker forgot to counterbore his sideplate. His was a clear design choice, that's a stylistic detail.

f I was using that style head, I'd use a matching counterbore. This would really locate the head of the screw, especially if the screw hole has a little clearance.

[bjmac]

Acer -
What is the best way to counterbore the sideplate for the screw head?

[Mark Elliott]

You purchase counterbores from industrial supply house that have various size pilot pins.   You drill the pilot hole in the sideplate, counterbore, and then drill; your clear hole, if necessary.  It is best if the pilot and clear hole size is the same, but rarely is.   

[Acer Saccharum]

What mark said. Buy counterbores from MSC or Enco. I like the c'bore with an interchangeable pilot. Same c'bore can be used for a #8 or a #10, if you have different pilots, and the screw heads are the same diameter. WIth an interchangeable pilot, you can tailor the pilot to fit the hole diameter.

[whetrock]

The mill-head type cutters with pilot pins will give excellent results. But it might be helpful to some guys to know that you can cut shallow counterbores like this with a spade bit as well. You do get a little chatter on the bottom of the hole, but the sides are straight and round, and (for me) those are the crucial details.
Here’s a photo of two holes I cut in a piece of scrap. Both were cut with the same bit. The first (with the screw in it) was cut with a brace and bit. The second with a drill press. Both are perfectly round. (Personally, I like doing it with a brace and bit. I can control the depth easily, without having to go to the trouble of measuring and setting up a tool stop, testing on scrap, etc.)

Note that this bit does not have cutting tips on the outside edge. If you have an old bit with such cutting points on the edges, it’s fine to just carefully grind those away.) You must pre-drill the hole for the screw shank, which is what you would want to do anyway, so as to be sure the hole for the screw is where you want it. (The point is that you don't want to let the guide point of the spade bit cut the hole for the screw shank. Pre-drill your hole for the screw. If you are concerned about the guide point messing up the main hole, then you can intentionally dull the cutting edges on the guide point.  But I didn’t do that with these examples.) The guide point needs to be of width to match the main hole. But maybe that is obvious??

You could make a spade bit with a round (non-cutting) pilot, as well. (The spade bits in the old 18th c. tool catalogues seem to be of that type, with round, non-cutting, cone-shaped guide points. But I'll have to say that I've only seen the catalogues, and not actual examples of the bits.)

[bjmac]

Thank y'all for the answers and explanations. (also the sources) Being the frugal (cheap) Scotsman that I am, I believe that I'll give Whetrock (PLB)'s response a try.