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

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