doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com 1883 Colt Trigger plate screw

I have an 1883 Colt S x S that I am restoring. Currently my biggest challenge is the trigger plate screw, it is seriously buggered up and I don't know the best way to removing it? Any suggestions?

Best to start with a long soak with a GOOD penetrating oil. It sounds like the screw will have to be replaced, but you don't want to make matters worse by breaking it or damaging surrounding metal. If you can get it out, you might be able to save the screw by TIG welding the head and recutting a new slot after dressing down. Also, it sure helps to have the old screw if you need to have a gunsmith or machinist make a new one.

A picture might help, as we don't know whether the screw slot can be used at all, once the threads are soaked. Patience is a virtue here. I've had some extremely stuck screws suddenly come out easily after several months of repeated soaking. While soaking, you could try tapping it with a brass drift to help the penetrant soak in. You could also alternate soaking and heating with a soldering iron. The abrupt change in temperature between the male and female threads can break the bond of rust, corrosion, etc. Did I say that patience is a virtue here? Rushing with dry rusted threads leads to galling, then you're screwed... pun intended. Gun screws are usually small, so things like E-Z Outs aren't likely to be any help.

If any screw slot remains, carefully clamping the action in a drill press vise and using a properly fitting bit in the chuck is a good way of maintaining firm downward pressure while turning the chuck counterclockwise BY HAND.

If that fails because the screw slot is too buggered, sometimes you can carefully cut the slot a bit deeper with a steady hand and a Dremel cut-off wheel. Going too deep into the screw head increases the chance of twisting the head off. Alternately, a small sharp chisel can be used to rotate the head counterclockwise by repeated tapping, but there is the risk of damaging surrounding metal, so it's kind of a last resort.

My all time favorite penetrating oil is Cabot's Tasgon. You likely won't find any because it was discontinued in 1983 due to creosote content. I only use it for more expensive things and things that can't be replaced. I don't even consider Kroil to be a penetrating oil as it has failed getting into threads for me so many times. I don't think it is any better than straight kerosene. I use my remaining supply on things that aren't real stuck, or as an assembly lube. Many folks swear by it... I think they need to get out more. I've had good luck with ZEP 45, pure oil of wintergreen, Burlite, and the 50-50 ATF/ acetone mix. I've tried everything I could get my hands on and most were disappointing.

Do you have a drill press or mill at your disposal? I use one of my mills, a tight fitting screw driver bit and a whole bunch of downward pressure on the quill, that almost always works.

I have used that procedure myself. It may take a few minutes to set up, but it paid off. I don't have a mill, but did it with a drill press.

WOW, a lot of very good advice. I do have a drill press but not a mill. I can send pics but I'm not very good at uploading the pics.
This is a very tired Colt, and it was used a lot. The screw is severely buggered. I've got time and am a patient person. I definitely don't want to do any further harm to it. I will continue to soak it and wait. The techniques you all mentioned at jarring the screw loose will come sometime down the road.

If the screw slot is chewed up but appears to have a chance at removal with a screw driver bit in a mill or DP, take some time to file the tip of the bit to sink into the slot as best as possible.
Then when giving it a try, place a small amt of valve grinding compound on the tip of the bit.
It will help the bit grab in the screw slot a little more than w/o it.
Use heavy hand pressure downward on the quill when trying to remove it. Sometimes very slightly turning the chuck/w bit engaged back and forth will help loosen things.

For heat, I place a brass (or steel) rod onto the head of the screw, Hold with pliers at the other end and heat the rod w/a propane torch. The heat travels down (and up!) the rod to heat up the screw.
A poor quality screwdriver blade can also be used. It will/can fit right down into the screw slot to transfer the heat.
Remove any handle from it especially plastic ones so you don't get a smoldering plastic while doing this.
Re-usable of course for this purpose,,it wasn't any good as a screwdriver anyway.

I like the valves grinding compound idea. Never thought of that. As for heat, I have usually heated whatever the screw is screwed into if possible. Heating causes expansion and would we not want the female part to expand more than the male part? Of course, most of the time I am not dealing with gun parts and precise heat location is not always viable, so everything gets hot.

All good information. Examining the wretched screw slot again, I'm thinking a very angry person, with a short fuse, attacked the screw with poor equipment and a heavy hand. But considering this gun is at least 125 years old, who knows what the real story is. Anyway, I'm here to bring peace back into its life and work slowly towards a solution. If I send a picture to someone more tech savvy than me, could they upload the picture so you all can see what I'm up against?

Hi Carl, It maybe that you'll just have to drill it out and make a new one. I can help if that is the case.

Carl,
Maybe you can clean up the slot enough with a graver (maybe shop made from a Swiss file) to grind a screwdriver to fit the wider slot and trap it between a drill press vise and spindle to keep it from coming out of the slot (it may twist the head off though), after long term soaking with solvent as suggested above. You may need to turn the screwdriver with a vise grip, tap handle, or similar, because the spindle and vise are in the way.
Mike

Carl emailed me a picture of the screw, so I'm posting it here. Carl clarified this is actually a floorplate screw and not a triggerplate screw:

I received the gun in old beat up condition but in very good honest shape except this screw. You can see all the pock marks around it from past attempts at loosening it! A cruddy mess! Any additional thoughts on jarring it lose?

The photo helps a lot Carl.

First the bad news... the damage is worst in the places where the screwdriver bit needs to apply counterclockwise torque, so it will be very hard to apply enough downward pressure to get a good purchase on what is left of the slot. Also, it is recessed deep enough that attempting to cut the slot deeper with a Dremel cut-off wheel would be impossible without doing further damage to the surrounding metal. So I like Mike's idea of carefully grinding a small graver to cut the existing slot a bit deeper.

The good news is that while it appears there is some rusting, it isn't a total loss like a gun that has been stored in a barn or chicken coop. There is always a bit of clearance between male and female threads. And rust occupies more volume than steel, so it tends to fill up those tiny clearances. Rust is abrasive, and greatly increases the amount of force needed to turn the screw. That's why long soaks with penetrating oil are important. Rust, or ferric oxide is also hygroscopic, meaning it draws in moisture, which leads to further rusting. So applying heat with a soldering iron or the heated rod or screwdriver blade as Kutter suggested drives off that moisture, increasing the chance that your penetrating oil can wick its' way deeper into the rusty threads. It often helps to alternately apply heat, vibration, and then hit it with more penetrating oil.

That all takes some time... could be 6 hours, 6 days, or 6 months. Most people aren't that patient, and will end up drilling it out and retapping for a larger diameter screw. I don't see any fresh shiny metal, so it appears you haven't gotten impatient and made matters worse. It helps to have some other projects to work on while waiting for these methods to finally work. My big disappointment with Kroil was that I noticed it often failed to penetrate down more than a couple threads, even when I let it soak for days with fasteners that weren't severely corroded or rusted. You will notice that some penetrating oils evaporate quickly, and will need frequent reapplication. ZEP 45 is one that does this, but it seems to work well if you keep at it. Same thing with the mixture of ATF and acetone, because the acetone is volatile and evaporates quickly leaving the more viscous ATF behind. So it may help to make a dam of clay or silicone caulk to contain a little bit, and then cover it with Saran Wrap.

There have been some past Threads here dealing with penetrating oils and screw extraction. The Burlite I mentioned earlier is made and sold by another member here (docbill), who gave us some good information on what it takes for a penetrating oil to work well. I'm not a lubrication engineer, but decades of using dozens of different brands has taught me they are not all the same.

Looking at the damaged screw, I'd probably cut an entirely new screw slot on the head.
Make it 90* from the damaged orig. Though the area on the right side looks very damaged as well, a new slot would take advantage of the yet undamaged metal on that side where the CCW
effort of the screw driver bit will push against.

A simple Graver chisel with a flat point and a very high Heel on it. That will allow the graver to get down into the slot as it's cut and not have the back edge of the shank of the graver dig into the countersink in the plate causeing further damage.

A simple flat edge/point graver can be made from a lot of things. A file with a thin thickness to begin with is one.

Grind the thickness further if needed to the width you want for the slot to be cut.
Put a flat bottom on the piece, then grind or stone the point to about a 45* angle. Anything more will tend to not want to cut too well after you do the next sharpening and that is to put a Heel on the bottom flat of the graver.

Simply put the now sharpened point graver on the bottom flat at the point on a stone .
Drag it backwards and it will stone a small flat on the bottom at the point. That is the graver's heel.
It doesn't need to be long. It only changes the angle at which the graver needs to be held to start cutting.
It also adds strength the sharp point on the graver
The higher you hold the graver above the stone, the more severe the heel angle will be.
If you stone a heel that ends up giving you an included angle betw the heel and the point that is close to 90*,,leave the heel and resharpen the point angle itself to a 'sharper' point.
It won't hardly cut at all if the included angle is 90 or very near it.

In normal cutting/engraving the heel is around 15* lift. Works well a lot of engraving. Most all engravers have a special spec they like. But in this instance
For this you want the heel to be more,,45* and more is OK.
That makes you lift the graver handle higher before the point actually begins to cut into the metal.

A high heel on a graver is used when cutting work down on a piece such as the inside/bottom of a bowl. Same idea, you don't want to nick up the high edges of the bowl with the shank of the graver.
That is what you want in this instance so the back edge of the graver doesn't touch the counterbore in the plate as you cut.

The high heel will make smooth cutting a bit more difficult than the lower angle(s). But you are not doing any scroll work in there ! It's just to chisel out a new slot.
It doesn't have to be pretty, just make it a deep as you dare and keep the sides of the slot straight up for the screw driver bit to push against.

Grind a new screwdriver bit to fit the new slot as tight as possible.
Then back to the drillpress or mill.



When all else fails, drill it out and pick the pieces out of the threaded hole. Make a new screw.
If you do get the mangled screw out and the threaded portion is still good, You can use it to make a new screw.

Turn or file the damaged head off of the screw. Down only as far as it will leave a 'cap' of the old head dia on the threaded shank.
Then silver braze a new head into place. Soft solder won't do even the newer greenie tin/silver stuff.

Turn or carefully file the new head extension to the same dia as the 'cap' that was left on the shank.
Leave the new head taller than needed and put a quick hacksaw screw slot in it. Doesn't matter where the hack slot is.

Use Color the new head with Sharpie or similar marking 'dye'.
Screw the thing into place , running it in back and forth a few times to seat it all the way. Then scribe a ring around the new head where it sit's level with the plate AND scribe a small 12 & 6 position on the extended head at the same time.

Remove the screw and now scribe those 12&6 positions down onto the head that will be below the surface. File off the extended head material till you are near the circumferance scribed line.
Don't go all the way to the line.

Move the 12&6 marks remaining on the head to the top of the screw head.
That will be your indicators for the new slot.
I use a Jewelers saw and .020 width blades for these type to cut the slot. A hacksaw blade with the set ground from the sides will do as well.

When you go to cut the slot,,back the cut up CCW from the 12&6 scribed marks to about 11 & 5 positions.
That will give you some extra effort in tightening it down when installing it for the final time(s!).
If you don't do this last little thing the screw will most often go in and tighten a little past 12& 6.

Now carefully trim the head level with the plate

I need more coffee now..

That is an awesome description.

If this gun were mine, I would be using a small Dremel bit to cut a new and deeper slot, then go to the drill press. I know the remaining metal to support a new slot is a bit lacking, but that would be my first attempt before drilling the whole screw out. Leaving a hard piece of drill in the hole after it breaks off is not a pretty sight.

First, thank all of you for your amazing input. The good thing is that because of past attempts, the aggressive attack has created a natural indentation and so far the penetrating oil is disappearing. I'm going to try to use my dremel bit to increase the slot if possible. But before I do that I will alternate between penetrating oil and soldering iron to get it loosened up as much as possible. Info to follow to all interested. Thank you again.
Carl

Kutter, your knowledge of gun stuff is only equaled by your willingness to help those of us in need.

What a gentleman you are. Bravo!

Gird your loins, It's out. Thanks to all of you It came out, not willingly but it did. There will be a picture posted soon. Mostly I have to say the penetrating oil seemed to be the most effective in all of this. I did a bit of several things before I clamped it in place and after the last treatment of penetrating oil had drained away. Then I gently tapped the best surviving section of original slot and it finally started to move. Ten minutes later the screw was in my hand. Wow, what a relief. So, do I try for a replacement screw(?) or revive this one. Seems like the best and most affordable alternative would be a used replacement?

Thanks,
Carl