Gun screws...the bane of me!!

F

fingers284

CGN Ultra frequent flyer
Rating - 100%
4   0   0
Location
Alberta Cowboy Ranges
Mostly "old gun" screws to be exact but with the odd modern manufactured gun included. Currently I am trying to find out the bolt size & thread pitch for a tang bolt on a Miroku manuf. 1886. I need to make two of them, one original length and one a bit longer to facilitate a tang sight installation. The original needs to be built because after removing it to start the sight fitting process it was "misplaced" so I don't have a "pattern' bolt to go by, only the threaded hole in the tang and not a chance will I have the eyesight good enough nor anything small enough to do an internal measurement.

I believe it is 6mm x either .05 or .75. I thing any Miroku (92's, 94's 73's maybe even the Browning 85 clones)will have the same bolt so if someone on here has a Miroku & a thread gage set I would be very thankful.


Some years ago I had a contact # for a Steve Holbourn in Ontario that had a Hardinge Lathe that he built non-common thread pitch gun screws on but that # no longer works, does anybody Know Steve or if he is still in business? His screws were expensive as I expect anything built one-by-one would be but the workmanship, accuracy of threads & length requested was prenominal ...and if it's the only game in town it's worth every penny.

Thanks to anybody that can help!!!
 
Dogfish858 said:
Grease the hole, thread in a chopstick or lead wire and measure off that.
Click to expand...

I thought of that with the lead wire, I thought I would manufacture a slightly undersized o d lead wire a bit longer than the bottom tang thickness and then gently give it a touch with the hyd press to fill the threads...but was sort of a last resort because it would require a total take-down of the gun.

Never thought of the chopstick thing tho and will give it a try, so thank you.
 
fingers284 said:
I thought of that with the lead wire, I thought I would manufacture a slightly undersized o d lead wire a bit longer than the bottom tang thickness and then gently give it a touch with the hyd press to fill the threads...but was sort of a last resort because it would require a total take-down of the gun.

Never thought of the chopstick thing tho and will give it a try, so thank you.
Click to expand...

Bad idea, and a recipe for spending time digging a lead rivet out of the hole.

Seriously, just spin a stick of wood in the threads. Chopstick, piece of firewood, stick off the tree out on the front lawn, whatever. Use the imprint to figure your pitch. Either make a threaded test piece to work out your diameter, or have the tang in hand to test as you come down to near depth on the screw as you make it.

The minor diameter of the hole can be measured directly. A tiny bit of trig, and you can come up with a pretty solid estimate of the major diameter. Then you know where to start testing the fit.

One thing I will mention. If Miroku copied the originals rather than re-engineering the fasteners to metric specs, there is a real possibility of some bastard threads in there. Winchester liked using an extra half thread in the pitch in some of their stuff, so it is worth keeping that in mind. This per some factory drawings published from IIRC, the Cody Collection.
 
fingers284 said:
that # only brings up the short front screw, not the long back one I need. they also list a bunch of long tang bolts for different guns but no "jap-chesters" that I can see...Thanks tho.
Click to expand...

It's for a set of both screws.
There is also a link there for an application chart. You could also phone them. If you click on the chart it shows that part # for Japanese 1886. 5th up from the bottom.
 
trevj said:
Bad idea, and a recipe for spending time digging a lead rivet out of the hole.

Seriously, just spin a stick of wood in the threads. Chopstick, piece of firewood, stick off the tree out on the front lawn, whatever. Use the imprint to figure your pitch. Either make a threaded test piece to work out your diameter, or have the tang in hand to test as you come down to near depth on the screw as you make it.

The minor diameter of the hole can be measured directly. A tiny bit of trig, and you can come up with a pretty solid estimate of the major diameter. Then you know where to start testing the fit.

One thing I will mention. If Miroku copied the originals rather than re-engineering the fasteners to metric specs, there is a real possibility of some bastard threads in there. Winchester liked using an extra half thread in the pitch in some of their stuff, so it is worth keeping that in mind. This per some factory drawings published from IIRC, the Cody Collection.
Click to expand...

Well, the chop stick thing was a total failure, this is a very fine thread that the wood wont "imprint even close" to a useable pattern.

The screw hole in the top tang is .240 (6.11 mm)so cant be 1/4" and minor hole dia.. in the threaded tang is .230 so very little thread engagement fro .230 to a max of .240. I do have a 1/4-28 die that I will try on a piece of 1/4 stock and file the thread tops down 10 thou. The original turn of the century Win. lever guns used a bolt .187 in dia. with a 28 thread pitch

Looky, my first call was to Western, even got the "helpful old guy" on the line but no joy.


Of course the "best bet " would be a call to Brownells...but what would be the fun in simplifying something that can be made much more difficult LOL.
 
I have had best luck by carving the end to a taper and twisting it in until it pretty much will not compress any more. Then twist it out and compare the spacing with the thread gage.

I have found that magnification helps a lot, when comparing. My brain may refuse to age, but my eyes... LOL!
 
I have read the tang sight screws on the Turnbull 1886, which is apparently built on a Miroku receiver, are a metric 5.5 x 0.5. That would be a metric fine thread. Five point five MM is 0.2165".
This reference chart might help.
h(spacer added)ttps://www.newmantools.com/tech/threadmf.htm
 
fingers284 said:
Looky, my first call was to Western, even got the "helpful old guy" on the line but no joy.
Click to expand...

Hahahah oh man...thanks for my daily laugh. Probably the negative universe polar opposite of customer service at that place. You got to find the humour in the SNL skit characters in our gun market in this country.

Numrich is my go to. Very helpful staff, extremely knowledgeable and a joy to speak with and deal with. They might have the info you seek.
 
pjs said:
M6-.5x1.859" long according to the Marbles website.
Click to expand...

Thank you for that, it is what I suspected it to be and a die cutter is available from KBC...or I could just order one from Marbles long enough to accommodate a tang sight LOL.

B_noser thanks for that info but .216 will slide right into the threaded hole, threaded hole is .230 thread crown to crown.
 
You must log in or register to reply here.
Back
Top Bottom