Fastening the Lock Plate on, One Screw or Two

[oldracer]

All my muzzle loaders, from the first one I assembled to those I have bought have all used two machine screws through the wood from the left side into the lock plate to hold it firm. Except one I bought recently from a member here that had ONE machine screw through the lock from the right side into the breech plug. The lock plate is solid but when I replaced the stock that came with the rifle with a piece of fancy walnut it was really hard to make sure there was enough of a flange for the backside of the plate to sit against. The left side is super clean looking so nothing interrupts the walnut grain. I am building a new Lehigh long rifle and have the barrel, lock and trigger inlet but have not drilled any holes yet.

What are you folks thoughts on one VS two lock screws?

[curator]

Two lock screws are usually needed for flint-lock or percussion,drum and nipple breech to keep the lock plate tight against the barrel. Otherwise, one lock screw will do for a percussion lock. How can you go wrong with extra screws?

[koger]

Most Silers use one screw, a lot of the older ones used 2. I like one screw if there is enough flange on most parts of the lock to hold it in place.

[Omnivore]

What's this talk of "flanges"? I know of no such part. The lock plate has a bolster into which the main lock screw is threaded and which sits against the barrel. The rest of the lock plate sits against the wood in the lock mortise. I never heard of any flange, and I cannot at the moment guess what that might be.

Anyway, the Hawken rifle, the late ones at least, had only the one lock screw just behind breech and they were considered strong rifles. Be careful not to have the head and side plate too close to the top of the wood on the off side. That's a common mistake I see in the custom builds. It is often wise to angle the screw upward to reach a small bolster, so it's threaded higher at the lock bolster end and the head sits a bit lower on the off side so as not to contribute to splitting of the wood at the side plate. You'll often see used rifles with a crack from the side plate to the barrel cutout where the offside lock panel starts to swoops down toward the centerline of the barrel.

The design of the lock plate and its bolster, and to some degree the design of the breech plug or hooked tang, will determine where you end up drilling the hole for the lock screw. I've seen breech plugs notched for the lock screw too, or even drilled clean through.

Drilling and tapping the threads in the bolster by running the tap through the stock will ensure good alignment of the threads, whatever the angle of the hole. In that way, you can somewhat independently determine the position of the screw head separately from the location of the threads in the bolster. There's no law of physics that says your lock screw must be perfectly square to the barrel, is the point.

I wouldn't use a second screw unless the style called for it, but it's your rifle and if it seems to want one, then go ahead. A second lock screw, farther forward, would have to slip through the thin web between the barrel channel and the ram rod, wouldn't it?, so it's position would be a little more constrained. The single screw would typically have a small side plate, or even a simple round washer, whereas the old flint long rifles typically had two screws and a largish side plate.

Here's one with two screws and very minimalist "side plates" consisting of round washers;
https://www.trackofthewolf.com/Categories/PartDetail.aspx/487/1/AAP-861

So there are always exceptions.

[bubba.50]

I'm not a builder but, my T/C's do fine with one screw and I haven't heard my CVA Mountain Rifle complain about wearin' two screws. the T/C's have an escutcheon about the size of a nickel & the CVA has little washers smaller than a dime.

and in my experience, overtightenin' the lock screws is what causes most stock splits.

[KCSO]

I think he is talking about the ledge inside the lock recess that holds the plate in place. The choice of lock screws is up to you have seen original rifles with either one or two. It all depends on the rifle shape and if you can get the front screw in place without running into the ram rod channel. This is where starting with a squared off stock blank helps rather than a pre shaped surface. I have an English rifle with only one screw that goes into the back of the breech plug and a hook in the front. As long as the lock stays solid when snapped you are OK.

[oldracer]

Thanks everyone for the feedback. The lock I have with one screw is a Ron Long percussion model and the barrel has a powder drum that sits down against the plate of the lock. The rifle I am building now is not drilled yet so I am mulling what to do and while I think about it I am working on smoothing the trigger guard, butt plate and any other sand cast pieces. The Ron Long lock has a 1/4 - 28 flat head screw while the last rifle I built uses a pair on #10 - 32 screws and they came with the kit. I'll let everyone know what I decide on when I get to that step.

[Omnivore]

Hmm, yeah; with a powder drum, which should always be supported by the lock bolster, that's once case where I'd probably lean toward a second screw. Still, with a tightly inletted lockplate, a mainspring that's not overly-heavy, and a nicely-fitted powder drum, you should be fine and dandy with one screw.

Anyway you look at it, the lockplate is getting jarred all over the place. Precise fitting is the best insurance against what you'll sometimes see in the old, well-used antique guns, which is the sloppy lockplate that's obviously been moving around in the mortise.

A little bedding could go a long way there, because you can get virtually 100% contact all the way around both the edges and the inside shoulder with that method. I've done that with some of my Italian guns which come with rather dubious inletting. If I were bedding during a custom build, I'd inlet the lockplate/bolster completely and then bed it before inletting for the actual lockwork. Then leave as much wood in the lock mortise as possible, for maximum support. That way you wouldn't have to mess with clay or other forms of "dams" to prevent bedding getting where it doesn't belong. Another thing the Italians do is they remove more wood than necessary in there, leaving less support for the lock and also weakening the stock unnecessarily in what is already the weak part of the system.

I bedded a patchbox once, not because it had gaps around the edges, but because I wanted full contact down inside the mortise. I bedded it before cutting the box cavity, so as to avoid the aforementioned hassle. Now it sits in there like a rock, with about 99.99% contact. Use a release agent, so's it'll come out again when required. The stuff Brownell's sells in aerosol form works great.

[lmcollins]

On flintlock rifles two screws are to be preferred. I state this because the action of the frizzen has quite a bit of torque.

The Hawken rifles that we see are all cap locks, and have no frizzen to be hit with a heavy flint filled hammer, and snap to a stop from their springs action.

[oldracer]

I forgot to post earlier, sorry but I decided on a single screw through the lock plate into the portion of the tang that sticks out the back after the tang is screwed in place. Seems to be very solid and the screw is nearly invisible so it should work fine as it does on the other rifle I have made this way. I'll post some pictures once the gun gets finished as I am doing the nose cap right now, then the butt place and finally the patch box. I figure it will take a couple more weeks?