doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com REPLACING A HINGE PIN

Chuck, maybe the hinge pin is straight (parallel sides) on that portion when it acts as a hinge, but the end (perhaps 1/4" or so of it, may be tapered for the purpose of securing it into the receiver....like any other tapered pin? Maybe, I donno.

I replaced a hinge pin in a LC Smith FW with the Brownell tapered reamer and pin supplied by them. My frame was annealed. Ream the hole with the barrels installed to the frame and you get a perfect tight fit. One thing to consider when pushing out pins from frames like the LC is which way the taper goes. You want to push on the small end. The LC Smith also has two small dowel pins holding the pin from moving and are on the fore end pivot surface. I found out the hard way and sheared them off. Other guns may have these or some variation and they can be difficult to see. Look at this surface on your LC and see if you can see them. It could be difficult drilling these pins if the frame is hard. Maybe a cobalt drill bit would work or one of the other space age bits. Some of the other higher Quality guns have the screw off caps to make hinge pin replacement easy with a straight pin. Those with machined in pins need the hook welded to tighten them up and there was a nice post about that here a couple of months ago.

The pin and the reamer used in the article(and sold by Brownells)
have a taper of 1/4" per foot, as stated by 2-P and me, in my post. Coffield shows and describes how he made a simple clamp to hold the barrel against the standing breech and down tight in the action. Then he reamed the hole and the hook to match the pin. When finished, the pin is driven into the receiver, excess cut off and smoothed. I think we're trying to make an ordeal out of a fairly simple job here. The obvious advantage, to me, is that everything fits together properly, as opposed to simply replacing the pin and having some mismatch with the worn hook. Hook, pin and hole are all matched, at the same time. I've never done it myself but I wouldn't hesitate to try it, after reading the informative DIY article. I have an Iver Johnson made Western Field, solid rib hammer gun that I use for BP cartridge trap matches. It's a little loose and seems a perfect candidate for a job like this.
Thanks to all

¼" per foot is standard taper for pins used in assembling many machine parts with these pins beimg availabe in sizes #6/0 @.078" dia (large end) through #10 @ .706" dia (large end). These pins can be had in lengths varying from as short as 3/8" (#6/0) to as long as 6" (#10) with sizes suitable for hinge pins in between. Thanks for pointing out this article Jim, as a retired machinist, interested in seeing his set up.
RedHawk;
The pins are a uniform taper for full length through the frame. I have seen some old guns which had a taper for the width of the lug, with cylindrical portions through the frame on either end. Many ols single bbl guns had the pin threaded into the frame on small end with a taper beginning at end of thread across lug. These often had a "Lever" attached at large end for turning in which folded down into a recess cut in side of frame.
PS; ¼" per foot = .020833" per inch. What surprised me on the LC's was the .018"/inch on the R frames. Perhaps it was designed prior to standardization of the taper pin.

Ok, I can see where the reaming of the hole(s) in the frame and the hook at the same time would indeed tend to produce an excellent fit.

I think Chuck and I know I, were looking at from the standpoint of how a tool maker or a machinist would approach a job like this on a first time basis.

Frankly, I was unaware and a little surprised about this taper pin business, but once it is explained, it seems to make perfect sense.