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Have a slightly loose lockup on my SxS shotgun. It is French, similar to Francotte and Helice designs. I have been told that lockup can be adjusted at the arbor pin by removing the hinge cap and turning the arobor pin which is supposed to be slightly eccentric or, perhaps just worn and in need of turning 180. Have any of you done this before or can you provide any advice?

Thanks, Tom
 

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The hinge pin is very hard, so the wear is going to be much greater at the hook on the lump. Putting doubles back on face is generally done by repairing the wear on the lump; turning the hinge pin (which is generally not possible) will do nothing to tighten your shotgun, if the wear is on the lump.
 

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MIke,

I know your right but I have a question about the whole hook/pin hardness issue.....Why?

Why did gunmakers use hard hinge pins and a softer lump? If you forsee that this is a wear point then wouldnt it have made sense to use a hard lump and a slightly softer pin, based on the assumption that pins are easier and cheaper to replace than lumps?

The Parker replacable wear plate is an example of this kind of thoughtful design...

Jeff
 

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First of all, the pin is much more difficult to replace than the hook is to rebuild. Once a new hinge pin is fitted, its ends need to be filed to the receiver and re-engraved. Also, you should remember that the hinge pin is in place during the case hardening process. Not only is it case hardened, but any carbon content in the pin causes thorough hardening during the heating and quenching required of the case hardening process.
 

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Mike, I have a question as well. Why, then, is the hook not hard like the pin? Can the hook be hardened, or at least made harder than it is?
 

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SRG said:
Mike, I have a question as well. Why, then, is the hook not hard like the pin? Can the hook be hardened, or at least made harder than it is?
Because if the hook is the same hardness as the hinge pin, then you will have equal wear on both surfaces. If the hook is softer, then all the wear will be on the hook (which is reletivly easy to fix.)

Mike Doerner
 
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