doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Bead front thread sizes?

Is there an online resource that shows/discusses thread sizes for bead front sights for shotguns? I need some quick schooling....

Not much help Mike, but both Hunter Arms and Philly made Fox guns used (unless ivory or Lyman was ordered) a taper press-fit brass bead, no threads.

English guns are usually a 6BA but occasionally 5BA and 7BA.

Even here in the UK BA taps and Dies are starting to go up in price because the metric system has now taken over in a big way suppliers claiming that the turnover BA has dropped considerably. Though it is ironic that BA stems from a metric platform, and I have also found some shotgun front sight threading to be British ME (model engineering) thread form. Though it will be a good chance that BA will be the correct threading but with Brit guns you can never be certain.

Basically I just need to know the next two smaller sized threads than the 8/40. I have a barrel with a custom rib; the rib maker told me he thought (this was made some time ago) it took an 8/40 threaded bead, but that is just too large a diameter to fit the threaded hole.

mike: here you go:
3-56 and 6-48. Both are probably more common than the 8-40, at least on the guns I have worked on. Gil

3-56 & 6-48 are a couple of sizes Brownell's at least used to sell bead sights in. They used to sell a kit, may still do, which contained three sizes of beads in both brass & aluminum in the 3-56 size & only the largest size in either brass or aluminum in the 6-48 size. The kit also included taps & installation & removal tools in the form of pin vices shaped to hold the bead. Other sizes may well be encountered but suggest you try a 6-48. Realize this is not a common hardware thread size but a special gun size, used for a lot of scope mounts.

Ithaca RayBar's are 6-48.
Some of the other beads that are mounted on a base of sorts use the large screw thread size.
That's actually quite a big hole for just a screw-in bead site itself but occasionally they are found..

Most common seems to be 3-56 for just a bead itself in my experience.

Various #4 and #5 machine screw thread sizes also show up depending on the maker.
I just put one on that was 5-48. Lucky I had the tap handy,,I don't think that's a standard size either.
I recall using 5-40 for shotgun beads in the past too but on what mfg shotgun I do not remember..
Remington & Stevens pre-WW2 pump guns are 3-56 IIRC.
Marlin pre & post war shotguns are also 3-56,,,
I know that combined w/the RayBar info is going to be a big help!

Those pin vises Brownells sold or still sells never worked well for me. Three different sizes, none of which ever held the bead well enough to take it out or re-install one.
Others seem to be able to make them work well. Must be me..

I just use a small drill chuck (a 1/4" cap from an old, dead Craftsman electric drill, the kind that didn't use a 'key' to tighten).
I polished the jaws smooth inside so they don't mar the bead. It's adj to any bead size and easy to use.

Many thanks, guys. It turned out to be a 6-48, or at least a 6-48 scope mount screw fits perfectly. So I'll get a 6-48 threaded sight from Brownella.