My! Three years! Where has time gone? Wifey accuses me of farting things off, but I really forgot this project until I was digging around for something else. So it's time to dive in & do the deal! No guts - no glory!!
First order of biz was take the gun apart so it would be lighter to work with. Also took the rib clear apart. I clamped the rib and not having a more scientific method, I lined up the rib perfectly straight ( and boy, howdy, that took a while!) and dipped a drill bit in paint to mark where I needed to drill.
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Net result looked like this. A real gunsmith would be banging his head on the wall about now. I took the rib off several times to be sure everything lined up square.
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Off-a to the garage after that. I did a light center punch to mark where the 1st drill bit would go. Compared the punch marks to the rib screw holes a BUNCH of times to make sure everything was square.
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There was quite an anxiety moment when I turned the drill press on, but again, no guts - no glory. Once you dive in, there's no going back. Since this is a cheep drill press & Lord knows how much run out is going on, I started with a 1/16 bit to make a place for the #31 bit to bite into with minimum chatter. Made a light cut & checked again and AGAIN making sure everything was lined up right. When that looked "eyeball right", I made a deeper 1/16 hole. With those in place, I chucked up the #31 bit (it's specific to the 6-48 tap) and there was minimum chatter opening up the screw holes.
Next order of biz was to tap the screw holes. I had a bottle of Tap-rite oil on hand & had ordered a tap guide to keep the tap perpendicular to the barrel while cutting threads.
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Actually cutting the threads was the easy part. The tap guide was worth the money! Cutting oil is also necessary - the tap cuts much easier.
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Then it was a matter of cleaning out the screw holes and actually mounting the sight on the barrel. Full disclosure here - one hole was about 2mm off & the screw wouldn't grab the threads. Well, 5 of 6 ain't bad for a bone head like me, and the rib is on rock solid. Lined up exactly right!
I'd rather be lucky than good!
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Time to test fire & sight it in? Not yet - I forgot a critical issue = I forgot to get a forcing cone cutter. You need a forcing cone, or you will be spitting lead shavings all over the place. I'll order one from Brownells & that's a simple operation - did it before on my old race gun.
Bottom line - truly anybody can do this... it's a matter of thinking out every step and thinking ahead. And being too cheep to send it off to a real gunsmith!
Always take your time - check and re-check every step. Once a drill bit hits metal, there's no going back.
Thus endeth sight rib installation 101!
SW