When I appeared to break off the taper tap in the Puma I was installing a Williams sight on a couple weeks ago, what ACTUALLY was happening was that I was simply saving money by not buying engraving tools - I actually planned all along on using the broken tap to engrave the receiver with an old family symbol - sort of a wheat stalk on it's side. I did a VERY good job of that engraving, making SURE it would be visible even after sight installation, and that it was really really deep, too! I also took the opportunity to teach my son some new 'vocabulary' words. So, the true kitchen table gunsmith can multitask!
Yesterday I spied a .45-70-SS Guide gun on the 'used' rack, and although stainless is hard to tell wear and tear on, this one didn't have any other 'family symbols' on it, or any messed up screws, and there appeared to be minimal wear; the price was great, so without hesitation I bought it. (Actually I did have hesitation, because the wife was home, and I didn't have the usual 'old gun case' all scruffed up that comes in handy to take 'that old gun I've had for years' into the house inconspicuously.
)When I went to put a Williams on it, I decided to use the top-mount type, so I didn't need to drill, but I did need to exchange the front bead. No problem, right? I had a couple firesight beads that were taller.
That's when I found out why the gun was so cheap. One light tap on the sight, and the whole ramp fell off, complete with super-glue residue.
However, the screws appeared in good shape, although only protruding below the ramp for maybe 1/48" (one thread). No problem, I used a chain-saw sharpening stone to countersink the ramp holes so the screws protruded more appropriately. Now for the tapping/thread repair (holes were so buggered up I couldn't tell if they had really even been tapped). I picked out the remnants of glue from the holes (more vocabulary words), then prepared to tap to the bottom of the dead-end holes. Now, as an amateur gunsmith, of course I didn't have a bottom tap - or so it would seem to the casual observer.
Here's where you see the carefully hidden genius of it all. Back when I broke that tap on the Puma, and it appeared to be a simple accident - THAT was me, 'making' my bottom tap. A few minutes with the diamond stone chainsaw sharpener, and it was ground flat on the end. (I'll admit, I didn't break it off perfectly flat as planned when 'engraving' the Puma with it, but it DID do a better job of DEEPLY engraving the receiver since it broke off with a nice pointy tip.)
Anyway, bottom tap freshly made, threads repaired, and I figure that 2 hours of work, extra vocabulary word practice, and one scratch on the Puma (I'll tell my grandkids that it was from a bear claw), and it saved me about $200 over what I'd have had to pay for a new Guide Gun.
Besides, I'll bet the ramp was that way from the factory, and the first guy who owned the gun probably shot it and it fell off, so he quickly glued it on and sold the gun.
So, in a way, it worked out that I broke the tap on the Puma!
Although I've never taken up engraving I have found that some so-called errors are blessings in disguise. 
