Indexed Floor Plate Screws
 

This is an old issue, covered in some detail in the Parker FAQ's and Brian Dudleys illustrated disassembly guide. I have a 1917 SC SBT s/n 177416 I just picked up from a member here. The gun is a shooter, not a collector. The three floorplate screws are not indexed. and only mildly buggered, so I pulled them without further damage and found they were equal length and marked +, -, and blank. Pictures attached. I cleaned the holes and the threads and reinstalled them with the - to the left, the + to the rear, and the blank to the right, but they didnt index. I rotated them three different ways, and none of the ways indexed even closely. I left them in what seemed to me to be the least unattractive position. My remaining question is this: How did these get out of index? Did they come from a different gun? I cant imagine they have shrunk or stretched enough to cause it. Whatever the answer is, it is not readily apparent to me. Perhaps one of our resident gurus has an insight that escapes me. Thanks in advance for all help. BTW, I'm going to keep and shoot the gun and not worry anymore about the screws. They are only a minor annoyance in our collective quest for perfection!

Screws
 

Know it can be frustrating, my guess is after 75-100- years of use and different people in and out of these guns the screws just move or change a bit. My experience the marked screw typically fit the upper right hole and the rear was a but longer.
My redneck fix that has worked for me is strip a 4-5”strand of copper lamp chord and wrap a couple strands around the screw several times just under the head basically making a copper washer to make up for displaced metal over the decades.

Does any one of those three screws index properly in any of the three holes?





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Nope, did the merry-go-round and nothing worked.

My best guess then is either they were greatly over-torqued at one time thereby stretching the threads, or they’re from another gun.





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Annie's screws looked kinda like that when I got her...actually they were turned outward rather than inward. I didn't like it but I shot her that way a good long while. After I got her back from having some trigger work done they are indexed. Don't know what the trigger guy did though.

When looking at the bottom of the gun, blank is left, - is right and + is at rear.

That is how they are supposed to be. They dont always go that way and line up. Sometimes you have to shim the screws if they go past where they should be.

Brian, is there a logic to this order of placement or just in your experience? In other words, should one insert and tighten the screws in the order you state? Left, right, rear?

Looking at those screws from the underside it appears to me that the threads were stretched downward indicating they were pulled down away from the screwheads from overtorquing.





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Wouldnt shimming under the screw heads to achieve alignment cause the heads to be proud of the floorplate by a smidgen (thats .001 to you machinists)?

Most often, when the trigger plate is taken off, it does not go in all the way, as it was before. I always tap around the edges with a small nylon hammer to seat it. If it's up .0005"(a half a thou) the screws will not be oriented as they were. Never use the screws to draw up the trigger plate.

A technique I was taught by Judson Darrow, long past, but the best gunsmith I ever met, was to take a sharp prick punch, and stamp one spot in the center of the thread end of the screw, that will put a small upset around the impression, and then tighten the screw back down. Alternatively, three prick punched impressions, in a triangle.

It's highly unlikely a screw with a perfect slot was over-tightened to the extent it stretched it. It is only the un-threaded shank that can stretch. Proper fitting threads, in holes don't stretch with hand tools, and the finer the thread, the more it resists deformity.

Screws
 

I haven’t had that problem, we are usually talking about quarter or less of a turn.