I have a gun with front and mid-beads, but the hole for the brass mid-bead was drilled a tiny bit off center. I'm a Libra, and every time I look down the barrel it drives me crazy. I like a little mid-bead on all my O/U guns, as my MX8 is set up this way. I think I have come up with a solution to the problem, that I can do myself inexpensively.

I have ordered a new .125" bead with the correct threads. I intend to install it, and with my Magnavisor and needle files reshape the bead from .125" to the correct .063" diameter. But, I will do so while working mostly on one side, so that the finished bead is perfectly centered on the rib, even though the shank is threaded into the rib a tiny bit off-center.

When mounted and looking down-rib, it should look perfectly centered. That is the simplest and cheapest solution I can think of. Whatcha think?

SRH

Good luck and take your time
Mike

Sounds just like something I would do. Perhaps some tape over the rib for a bit of finish protection.

People who drill off center holes in ribs should get three days in the electric chair. It's inexcusable when this is all you need to center it perfectly.

https://www.brownells.com/gunsmith-tools....aspx?rrec=true

SRH

Most likely when your mid head hole was drilled they failed to mark the location with a punch. When they drilled the hole the bit drifted slightly to one side and caused to hole to be off center. I’ve seen a lot of sloppy work because people don’t hold work well, don’t do each step properly and just take too many shortcuts. Fixing screwup is a lot more difficult than doing it right the first time.

The way I have repaired this issue in the past is to mill a hole for a tight fitting bushing in the center of the rib. The bushing is threaded internally for the bead and then lock tight is used to keep the bushing in place. Yup, way more work than drilling it in the correct spot the first time.

If you have a tap for the threading, maybe you can screw it into a sacrificial holder and work it off the gun. Just make a little removable or not orientation mark that won't get ground off, and maybe save just a little fine tuning for on the gun. Relatively, that's a fair bit of reduction and you may want better access if you're trying to hold a bead shape by hand. Good luck with it.

You do need a bead. I had been shooting sporting clays without a bead, did not notice until someone pointed it out.

John

I have one with two mid-bead holes, quite close to each other. One filled with a bead and one with something else. I don't like either of them, and though of filling them with a tapered rod and seeing if an engraver could make them inserts match the matting.

Could have been, or they might have used a cheap drill bit that wandered before biting. Good, split point bits won't. I have found some split point bits that are absolutely amazing. I bought a set of fractional sizes for the farm shop, and am about to bite the bullet and buy an index of wire gauge sizes for the gun shop. They ain't cheap, but they are fine. Sold by Kimball Midwest, and coated with titanium nitride or something else gold, but let me tell you what sold me on them. The salesman stopped by my farm shop and asked if I had a 1/2" capacity drill motor. I said I had a big Dewalt T-handle job. He asked for it. He then clamped a 5/8" grade 8 capscrew, about 4" long, in my big vise horizontally. He put a 1/8" drill bit in the drill and said "Watch this". He started the split point bit into the round shank of the bolt with absolutely no wandering. Mind you, this was not a flat surface, this was a round bolt. He drilled through the bolt horizontally and when it came out the other side he stopped the drill and let it stay in the bolt, took his hands off it and let it hang, the tiny 1/8" bit supporting the big 1/2" drill, bending the bit in a curve, but without breaking it. He asked if I was impressed, to which I replied that I was. He said "Then watch this", and proceeded to run the drill and pull down on it causing the flutes to cut into the grade 8 bolt. He kept this up, with the bit in a curve from the pressure, until the flutes cut the bolt in half! The bit never broke, and I asked how much the index set was, and bought it. That was several years ago, and I've never broken one. Split point bits are something else, and these are some kinda tough.



You can, but I like mid beads for guns that I premount, and this is a subguage competition gun, though it gets used on doves as well. There was a thread that you could do a search for, on here, that showed the before and afters for just such a job. It was invisible after the work was done. Sadly, I don't have any guns worthy of such tedium.

SRH

I thought about that craig, but decided it would take too much figgering to get the bead to tighten up at the same orientation in the holder as in the rib. I'd rather take my time and carefully shape it in place. I have no doubt I can do it. I'm a screwball............I actually enjoy tedious filing and shaping.

SRH

I was thinking more along the lines of not worrying about the alignment. Maybe, stick it in the end of some rod stock or an old bolt. Then, quick rough grind it like a tapered pin vise were holding the bead. Could always make two careful marks at 180* to keep oriented with the direction of the rib if it'll help to visualize. I'm not arguing, you'll git 'er done and nicely, just thinking about clearing that rib out of the way for a little bit. I think you came up with a good, practical solution

I have a Thread Check'r that it will screw right into, but with a little blue painter's tape on the rib I don't think there will be much advantage. I really have a lot more confidence in the end result if I do the job "in place". The only way that shaping it somewhere else would work is to install it in the rib, make a mark as to orientation, then remove it and screw it into the "fixture" at the same orientation. Even then I am afraid I might miss it a bit. Doing it in place means I can look "downrib" as I work....................invaluable.

Thanks for the idea, craigd. That's what makes this forum such a great place.

SRH

This is a problem that is more common than a lot of people think due to people fitting beads themselves , I have solved this problem a number of times but it is a complete an utter pain to do. Because I feel that you will only get one chance to correct the situation it is down to hand tools to correctly re-position the hole, using a needle file then re-thread using the next tap size larger, then make a bespoke bead with the new thread.
Re-fitting of a bead this way makes it a cure for a mistake undetectable.

It's tough to reposition a hole and tap to the next larger size when the hole is already .118". That's suitable for 6-48, which is the biggest thread size I know of that is commonly available.............thus my idea. It's not a super expensive gun so I don't want to throw the bank at it. If it were I'd fill the hole and have it engraved to match the rib matting, then start over with a new hole.

Thanks for the input, damascus. I'm going to try my idea. If I'm not satisfied with the way it turns out I can always go another route. I like SKBs fix, and had considered that, but just don't want to sink too much dinero in this job.

Waiting for the beads to arrive...............SRH

Stan I know this information is rather to late but on second thinking my post I should have added a little more information. Other than guns my other love in life is making clocks and we clockmakers have solved the screw thread size problem a long time in the past. To this end we have screw plates that go up in very small increments unlike engineers taps and dies that increase in standard size and screw pitches.
In the photograph is a clockmakers screw plate with its set of taps, from memory that particular one ranges from .7mm to 2mm in 14 steps they look expensive but the one in the picture costs £13 and you can find them on e-bay. They are made from carbon steel not high speed steel so a limited usable life though over the years I have gathered a collection of these of sizes you would not thought possible, the thread is only standard to the taps that come with the plate in other words just a screw thread. The one thing that sets this system above every other method of generating a thread is that no matter the diameter of a thread needed this system will produce it for you. These plates are still found in instrument and clock workshops because they work to produce a thread and a matching threaded hole when all else fails.

Thank you, damascus, for that post and picture. There have been times when a set like that would have been very handy.

For an update on the project............. I took an entirely different route than what I had planned. Turns out that the hole in the rib for the mid-bead was smaller than the front, which was 6-48. The mid-bead hole was actually threaded, and was 5-44. It was not too far off center, so I enlarged the hole with a Dremel burr, on one side, so as to center the hole on the rib. Then I drilled and tapped it for 6-48, ordered a tiny mid-bead with those threads, and screwed it in. Perfectly centered now, and impossible to tell that it was ever buggered up.

Thanks to everyone for the ideas and suggestions.

Best to all, SRH

AWESOME