doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com top screw out of time

the top screw under the lever is out of time. Someone recommended I remove and file material off the bottom of the screw until I can get it tight but in time. Sounds logical. Am I safe doing this?

Nitrah;

Before you do anything ask yourself why it is out of position. When the gun was made it would have been placed in the correct position usually with a lot of force applied to the screw slot. Ask yourself some questions like this: has the gun been re-stocked; does the butt stock now have a great deal more expansion to it because of the humidity where it now resides; is there any thing interfering with the original stockmaker cuts allowing the bottom tang of the action to come into its original position; do you have a screwdriver(turnscrew) of proper size and strength to tighten the screw--if it is a British made gun it originally was likely tightened with a brace. If you do not know what a gunmakers brace is then watch some of the Gunmaking.UK series on youtube.

I do not recall every finding a top lever screw (breech screw/pin) that needed to be filed such as you described, it was always something else that kept the screw from going to its proper position.

Kind regards;
Stephen Howell

Stephen, thanks for responding. It could be a restock, it is a C Boswell pigeon gun from the 30's and stock is in remarkably good shape. I have a proper turnscrew, but not a brace. It is tight with the slot at 3 o'clock

I would certainly follow Stephen's advice,, but what would filing material off the bottom of the screw accomplish, wouldn't you have to remove material from the bottom of the screw head to have a turn in tighter?

Nitrah;

Being tight at the 3:00 o'clock position could be a symptom of the hand of the butt stock shrink allowing the breech screw to turn too far.

Stephen Howell

The question I would ask is if the screw has turned beyond its original position or if it’s not all the way back to the original position. Then determine why it’s not in the correct position. If it’s gone beyond you might consider a spacer to line it up.,

I'd be leery of filing off the bottom if I thought it would leave the head of the screw recessed.

I'd be more inclined to add a spacer.

Rather than guess, you can do the math.

It sounds like you were 90° off.

90° less? Or 90° more?

What is your thread pitch?

How far in does the head of the screw go in 360°.

A piece of feeler gauge approximately 1/4 in thickness of that distance should give you a very accurate shim to place under the top strap if you want to.
No machining, just a pair of scissors.

Action pins are usually made out of low carbon steel. And then hardened. Simple fact is that over time, and depending on how the pins were initially fitted up, and even how good the threading dies and taps the craftsman was using when he made the pins, to how many times they’ve been loosened and then torqued down…they can wear out and start to over turn or go past their intended index point. You see this not only with breech pins, but on top lever pins, and cover plate pins.
As Steven has mentioned the breech pin out of index can be from a number of different causes, as can the hand pin. These two pins do more than just hold the stock onto the action. The breech pin actually bears on the wood and when tightened will draw the head of the stock tight into the action. That’s why that pin is normally tapered.
Nobody notices a hand pin that isn’t tightened down completely because its slot is hidden under the trigger guard tang in most instances. Take a few guns down to the bits and you’ll start to notice that hand pins are usually pretty loose. Tightening them down will draw the rear of the top strap further down and you’ll start to see the pin protrude from the top strap, which will need to be filed flush so the safety will work correctly and for aesthetics.

I don’t think I’ve ever heard of or seen a craftsman using spacers to correctly index a pin. Can you provide an example of this method (pics or vid)? I’d be interested in seeing the method.

Most craftsman will just make new pins to fit. I’m making a few right now. I just finished up making two new cross pins for a Greener FP.

A shim is a stopgap for most folks until the gun can be properly repaired if the cost of repair is warranted by the value of the gun.

If the wood has dried or shrunken for some reason, the top screw will rotate too far and be to the right of the index point. It can be caused by having the stock off and retightened to hard, thereby compressing the wood. I have fitted shims to correct this if the amount is slight. Often though, it can't be very thick or it will index at a point above the surface of the tang. It is generally caused by a wood problem and not the screw or head seat wearing. If it won't turn far enough to index, it is often due to interference in the screw head seat, under the top tang or interference in the action inletting.

Ok. Can you explain where this shim is placed to correct the pin timing?

Just under the pin. But this is so obvious that I think you are trying to make some other point.

Nothing nefarious here, dude. I’m asking because I’ve never seen this or heard of someone adding a shim to correct pin timing. It’s a serious question. Relax.
Every gunmaker I know just makes a new pin that tightens & times correctly. Back in the day some gunsmiths used to recommend having the head welded up and then refit. I and many others thinks it’s faster and easier just to make and fit a new pin.

So…..I’m curious and would like to see how this method of shimming to time pins works and how it’s done.

Shimming is just a at home patch. Not a gunsmith fix.

A proper shim repair includes gluing a thin layer of wood in place and re-inletting, I have done it a few times and it works fine in certain situations.

As to the OP and his screw head that is out of time, follow Bushveld's advice, figure out the why and then what the proper repair would be.

The way I've seen it done is by making a tiny flat washer out of the thinnest shim stock you have, then placing it under the head of the pin and tightening it down, then verifying the position of the slot. If more is needed you go to the next thicker shim stock. Simple trial and error.

Sorta like shimming the hook on a double gun that's not worth paying to have it put back on face. Like my BSS duck gun.

Dustin, I've read about adjusting the timing of a screw slot by doing exactly what Stan is saying, as an alternative to either machining a new screw or making adjustments to an existing screw by either adding or removing metal from the bottom of the screw head. The "shim" or washer can be made out of very thin sheet metal, plastic shim stock, or even waxed or oiled paper.

If you know the pitch of the screw threads, you can even calculate how thick the shim needs to be to move the slot the desired amount. In this case, the head needs to turn 90 degrees either way to align the slot at a 6:00-- 12:00 position. So if the thread pitch is 32 TPI, you would divide 1 by 32 which would equal .03125" for each full turn. Then divide that .03125 by 4 and the result would be .0078125" for a quarter turn. So a shim or washer .008" thick would get you very close to the 90 degrees of movement needed to align the slot.

Of course, there are various ways to get to the same result which have been mentioned. One other way would be to cut the countersink for the screw head a wee bit deeper. But it may just be a matter of a screw which is either turned in a quarter turn too tight or too loose. If it is already good and tight with a good hollow ground screwdriver, cranking even tighter with a brace or using more force also risks exceeding the yield strength of the screw, or even breaking it

That is interesting, Steven. Of all the gunsmithing books I've read I don't believe I have ever read of that technique. I would like to learn more detail about how the thin layer of wood is created and glued in.

Thanks for bringing up that procedure. If there is anyplace you know of that I can read more concerning it, I'd surely like to know about it.

When I competed with a M-21 Winchester this was a common problem as the trigger pulls were maintained by the position of the trigger plate distance in relation to the receiver. This was controlled by the thickness of the stock in the grip area. The stock bolt would need to be adjusted to compensate for humidity and about every other thing you can imagine. It was that critical.
I fixed this by building a metal tube inserted into the stock for the bolt to go through and milled it to length so I could snug up the bolt and problem was solved. This was done on two M-21 guns and was a permanent fix.

Stan,
I don't recall ever reading about the technique, I just ended up working out a sound solution to a problem that appeared in the shop. I'm always doing woodwork and have saws, sanders etc. so making a thin wafer of wood is easy enough. I have done the same repair on the tangs of doubles where there is some wood loss around the rear tang screw. This is pretty much how these problems were addressed before the invent of bedding compound, add some more wood and inlet to the required depth.

I really enjoy seeing high quality vintage wood repairs come through the shop. One of my favorites was a Fraser falling block a client owned, it went back to the factory for a new barrel and top tang safety conversion and fore end was re-used, the new barrel was a smaller diameter and the dutchman used to fill the gap was world class.

I hope that helps.
Steve

in this case adding a shim won't help. The screw head is tapered, so thicker on one side and I need it farther in to enable the top lever to clear it. If I back it out part of the screw head sits up proud.

I'm rather limited on funds and old wood does all manor of things. I shim or add wood and re inlet if needed. Where the shim goes is pretty easy to determine. If the wood is proud at the top tang, shim at the top. If the wood fits perfecta shim under the trigger plate works. Store bought waxed paper works well for minor shims, wood and re-inleting for major stuff. I've had a couple drillings that the side safeties that would bind and a paper shim or two under the trigger plate solved the problem for a couple cents. The drilling now shoots safely and usually brings the tang screws back into proper alignment because the wood has compressed over the years. Because the trigger plate is shorter than the top tang the compression is there.

Okay, so now you have determined what the issue is, now you need to figure out why. The pin could be damaged, so could the trigger plate it screws into. Has the top lever spring been replaced? Sometimes a replacement top lever spring can interfere with your inletting. You can use inlettting black to see if something is stopping the metal from seating to the correct depth in the wood. If the metal fits as it should to the wood, also see if the pin will fully seat in the metal without the wood installed. You mentioned it might be restocked, check to see the pin is not binding on the stock.

Let us know what you find.

Steve

If the screw is turning too far, which is almost always the issue, a shim will help. You may have to try a couple different thicknesses, but something should return it to original spec.

The slot is at 3 o'clock,,but is that the end pf the screw slot that SHOULD be at 12? (overtightened),,or is it the end of the screw slot that should be at the 6 position (not tight enough).

Maybe you have already figured it out, but many time the screw head out of time will display edges around the circumference that are lower or higher than the tang counterbore hole itself.
Those high and low edges can tell you if the screw needs further tightening to time it,,or needs to be backed off too time.

If it's been restocked, that might be what's causing the issue.
Not being able to pull the lower tang into the same position it was on the orig stock,,or it may be that it is pulling the lower tang up just a bit more and over tightening as far as the timeing goes.
Check the draw surface on the stock,,where the slanted front of the trigger boss pushes on the stock.
If a restock, that face of wood may need a very slight shaving down to allow the top tang screw to pull the trigger plate upwards a bit when turned tight and will let you time the screw head if it needs more tightening.
Glue a thin wood slat onto the surface and re-fit if the screw is over tightened.

I've seen plenty of shims placed under screw heads to make them time.
Everything from a loop of very thin wire, to a paper or thin card 'washer', to a washer made from metal shim stock as already mentioned.
The last two, you punch a hole in the center with a common paper punch for the screw shank.
I've seen the bottom outside edge of the screw head peened downward a bit to make the head engage the bottom of the counterbore earlier to tighten things up and time it.
Also soft solder added to the underside of the head to make it bottom out sooner.
There's a method to tighten the draw using nothing but a hammer. I use it quite often on smaller screws. I'll keep the secret,,secret! (it's probably widely known now though.)

My mind is always trying to figure ways to solve problems, and I just thought of this. Steve, Kutter and others who have more experience, please comment.

In lieu of gluing in a thin wafer of wood, then re-inletting the pin to the correct depth, I wonder how well it would work to use cyanoacrylate glue and build it up with a mixture made from it and walnut dust. It should be very easy to control the application of it, and it would seem to me that it would harden sufficiently to provide a solid seat for the underside of the pin head. I know that type adhesive is used to strengthen walnut in areas that are subject to compression and cracking, because in its thinnest form it soaks into the grain freely. Once thoroughly dried, one should be able to relieve the built up area to clock the pin slot.

I have several little jars of walnut dust, in various hues, in my shop that I captured with a belt sander for hiding repaired cracks in stocks, with cyanoacrylate.

The glue solutions are fairly effective.

In situations where maintaining the appearance of originality are not a concern the most effective long term fix is to build steel pillars and fit to length. They capture the screw and give a solid stop. Last the remaining life of the gun.

I did exactly that to the front and rear tang screws on the the two M21’s I competed with. Had no problems related to tang screws or triggers after that. Wish I had done it years sooner.

That should work Stan, pretty similar to bedding compound, not runny and will do the job. I like inletting wood better than a plastic type of filler, so if fitting is required after build up, I prefer wood.

Mr. Potter once shared with me that there are wrong ways to do a job, but quite often more than one good way to complete a repair exists. I think your idea has merit. I use sawdust combined with wood glue or CA myself. Certainly worth a trail run, even if just done a piece of scrap to get a feel for it.

Steve

I wonder how a small O ring placed under the head of the screw might work? O rings come in many different sizes, diameters and material. I only suggesting this might be a possibility. I have never tried this but I would think the O ring might conform and might work. Obviously not a professional repair but might be a quick and easy temporary fix.

I also recall using a very thin cone shaped stainless shim under the heads of #8 and #10 screws where the top material under a nut plate had worn and was slightly oversized and going up another size fastener was not feasible or cost effective. Again I never tried this on a firearm but I need to see if I can contact friends still in the business and see if I can obtain a few to experiment with.Similar to what Stan mentions about making a shim.

Just conversation Stan. If the action functions correctly, but found to be inletted too deep, why not bed with a good epoxy instead? Back the screw off to in time, plus a little. After bedding it, should be able to snug down into time.

Stan, Richard, et al;

There are all kinds of way to repair a butt stock for the subject issue and it is good to see all these comments and experiences. It brings to my mind what I did a decade or so back with a Birmingham made A&D (boxlock) gun. The internal wood of the gun was falling apart, but the outer layer of the hand of the stock of about 1/4 inch thick was good. I cut the center of the hand of the stock out and fitted an oak insert glued in place; then re-inletted the hand of the stock to the action. I am satisfied that others have done the same.

Modern adhesives are marvelous, and certainly a compound of walnut dust and the proper adhesives is worth the time and effort to use.

Kind Regards;
Stephen Howell

I hate to interrupt.

Comes to mind the expression, first do no harm.



95% of you could put a drop of clear nail polish underneath the head of the screw
Tighten it to wherever you want it and then let it sit overnight.
Because there isn’t really much use going to happen. Nothing is going to knock the screw loose.

It ain’t the space shuttle.

Yah, but the other 5% want to know how to do it RIGHT.

A drop on nail polish was certainly not going to hold on my M21’s.

It's tough to determine what is exactly right sometimes. For a Best Quality British or a very high grade American double shotgun many would agree that a perfectly timed custom made replacement screw is the only acceptable repair. The idea of perfectly timed screw slots is mostly a vanity thing reserved for higher grade and hand made guns. Quite a few manufacturers gave virtually no thought to screw slot timing on lower and mid grade doubles. You can find well regarded guns that have visible screws that are set in position with a smaller lock screw, where the head of the lock screw is inset into the perimeter of the main screw head, yet the main screw slot is not timed.

Early on in this Thread, someone said that the method of using a thin "shim" or washer under a screw head did not constitute proper gunsmithing. However, for the vast majority of field or mid-grade guns, it simply wouldn't make sense to pay a Purdey trained gunsmith to make a screw from scratch. The video that was posted separately on making a gun screw was very incomplete. It didn't show anything about selecting the proper screw stock, machining of the threads, or any engraving, or correct bluing or finishing. All of that work just doesn't make economic sense for the majority of guns, and most guys would be happy with a good used screw from Numrich, no matter where the slot ended up.

It is interesting to hear the various thoughts or methods available to accomplish the goal of timing screw slots, but for the most part, there isn't much new under the Sun. The idea of mixing cyanoacrylate glue with sawdust as a filler sounds very much like epoxy glass bedding. Rotted or punky internal wood has been replaced with Baltic Birch plywood, and inletted to fit. Same for pillar bedding to maintain spacing between top and bottom tangs. And the method of gluing in a small piece of wood, and then inletting to fit has been mentioned here by the Stock Doctor DES/TSD, and certainly wasn't invented by him. Some of these repairs might be a big disappointment if found inside a gun that was represented as unmolested and original.

Nail polish. Yeah, I think I will dub that the Grey Man fix. If only I can remember it. You come up with so many.

It works, and people would be lying if they said they don’t do it, because I have found it way too many times, but a 1032 screw twists off at about 7 1/2 foot pounds and can put about 2000 pounds of compressive force between the pieces that are being tightened together.

And what do you know, the compressive force for cyanoacrylate glue before it will creep is about 2000 pounds.

A little dab’ll do ya.

Many of these pins experience almost 0 torque.
The adhesive force far exceeds the rotational force.

I guess you can call it clear Loctite.