Numrich Stud Thread Sizes??

[Rich B.]

I am replacing some worn parts on a 5-screw S&W M&P .38 Spl 5" bbl and noticed that all three frame studs are loose.

Numrich has threaded studs listed in their catalog/site, and they were cheap enough to add to an order. Now that I have them, I can't tell what the thread sizes are. Travers has the specialty taps I need...But what size???

Here's the Numrich studs -

358220A Trigger Stud (threaded)
358200A Hammer Stud (threaded)
358240A Cylinder Stop Stud (threaded)

Has anyone else tapped their M&P/K frame for the threaded studs??? I'm afraid my old eyes & cheap thread gauge can't tell...

Thank You!

 

[chief38]

If someone you know has a Starrett or Brown & Sharp Thread Gauge you could ask them for their help, or simply call Numrich and ask.

When taping small holes I like to use my Drill Press vise and Drill Press Chuck to assist in tapping perfectly straight (WITHOUT the motor being turned on of course). If the hole is threaded a little askew things might not fit correctly when you are done.

https://www.youtube.com/watch?v=KBrrVnYBPOQ

 

[Rich B.]

If someone you know has a Starrett or Brown & Sharp Thread Gauge...

*I* have a Starrett thread gauge...

The threads are too small and there are not enough of them to get an accurate comparison...46 or 48; 54 or 56...

I use my milling machine with a Jacobs chuck in the quill to tap holes...Works great!

 

[chief38]

Then I would try different sized nuts that you suspect the thread to be and see which one fits properly. If they are not available in the Hardware Store
and you don't have a good selection to try, PM me and I will see if I can help you out.

You did say you had "a CHEAP" thread gauge, that's why I reco'd. a Starrett or B&S.

 

[Rich B.]

You did say you had "a CHEAP" thread gauge, that's why I reco'd. a Starrett or B&S.

I suspect it is the 'entry level' or economy gauge...Only 16 leaves; 44tpi to 6tpi...I got it back in the late 60's when I worked in the aerospace industry; never saw any need for a more expansive one...Even now, these studs only have 1 1/2 to two threads per stud (the thickness of the S&W gripframe)...They're just too small to get any kind of accurate reading...I can only estimate the fractional size...

I can try screwing them into various firearms I have and see if any fit...

My question here was in the hope that someone had already tapped out their old frames for the Numrich studs...

If I get a positive confirmation of the stud thread sizes, I will post them...

 

[mayuhm]

I've kind of been waiting for someone to tell you to just tighten up the studs you have... I believe they are threaded in the frame and screw in righty tighty... I made my tool from a S&W sight adjusting tool just for the heck of it, back when they were a giveaway item. Drilled out the center of the tool and then filed away to make the "ears" to go in the notches of the stud. Same tool you will need to put in the new studs
It may be that your piece does not have the studs that screw in, but I kind of thought that they all did, at least the older ones. That was why I was waiting for a maybe more experienced response.

 

[Rich B.]

At least one [trigger] does not have threads. It comes right out.

I'm thinking of ordering a half dozen taps from Travers, using the old frame holes as the shaft size, and as close to what the thread might be as possible to eyeball...48, 56, whatever...And drill & tap a piece of scrap and try the new studs in the tapped holes...Then tap the frame...

I guess it was a long shot that anyone else had tried the Numrich threaded studs...

Ya wins some, ya loses some...

 

[vonn]

At least one [trigger] does not have threads. It comes right out.

I'm thinking of ordering a half dozen taps from Travers, using the old frame holes as the shaft size, and as close to what the thread might be as possible to eyeball...48, 56, whatever...And drill & tap a piece of scrap and try the new studs in the tapped holes...Then tap the frame...

I guess it was a long shot that anyone else had tried the Numrich threaded studs...

Ya wins some, ya loses some...

Please keep us posted on your results. I have a thread gauge I got from Brownell's they call it a " Screw chek'r might be worth a call they have helped me many times in the past.

 

[Rich B.]

Please keep us posted on your results. I have a thread gauge I got from Brownell's they call it a " Screw chek'r might be worth a call they have helped me many times in the past.

I have the Screw Chek'r earmarked for my next Brownell's order; Thank You!

None of my holes are tapped; the studs all have knurled flanges. Pic attached. None have the spanner holes in the flanges either.

I'm not all that annoyed at the loose studs; it's not a tack driver. It's just old & worn. I'm working at getting the cylinder timed with a new extractor & new hand. Haven't done any S&W/Colt revolver work since the 80's, and CRS is affecting me these days.

 

[mayuhm]

How did this all turn out?

 

[Rich B.]

How did this all turn out?

For me? Inconclusive.

Numrich never answered my email; posting in their Forum got no answers either. That particular handgun has been shelved for now; other projects being worked on that have simpler solutions.

Some days you eat the bear...Some days the bear eats you...

 

[mayuhm]

So,... I'm sitting here looking at your picture with my brain in problem solving mode, thinking if I had some measurements I could spin you up a staking tool, which would ultimately come down to my lack of "hardening" skills for the final touch in the making of the tool and it occurred to me that the tool is much like a hole cutting punch... not quite as sharp of course, but if using a cheap tool that dulls fast.... see where I'm going? I do not know the needed dimension of the "ring" used in staking... if it is a standard "hole" size. I don't know if that idea would be of any use.
If not, I will be happy to spin up a tool...maybe it would last a smack or three to get that stud staked back in tight. I would need the diameter and length of the stud and the diameter of the "ring"... the original staking mark around the stud hole.

 

[paulj84003]

If your old studs are in good shape. Push them in place with loctite 609
in the frame holes. Put the side plate in place till the loctite sets up. Obviously don't get loctite on the plate side of the pins. Paulj

 

[Rich B.]

I took a shot at staking the loose pin in place, using a 1/4" tap with a needle point...Just three dots, because I didn't want the displaced metal to push the pin out of alignment. Didn't work. I didn't want to hammer too hard.

The circle stake is interesting; I could make 'hole punch' circle staking punches out of SHCS's or Grade 8 bolts; drill the center, bevel the outside edge, harden in oil & temper...Then try it. I would need three different sizes, as there are three different sized studs.

I do not like LocTite; I had an experience once with the "non-hardening" thread LocTite that stripped the thread when I tried to remove the bolt. Since then, I only use contact cement to lock my threads.

Plan D would be to make new oversize studs and press them in with my arbor press. I would use SHCS's again or Grade 8 bolts but not bother hardening them. I think this is the best way to go about it, but my Chinese 3in1 mill/lathe/drill isn't too accurate at very small sizes...And to be honest, micro-machining isn't my best skill either...

But I think that is what I'll try, since there is no way to figure out the thread sizes on the Numrich threaded studs. I can get the taps from Travers; they have extra-fine/small sizes, but I don't want hundreds of dollars of taps that I'll only use once.

Thank you, gentlemen, for your help!

 

[Tired Gunsmith]

I no longer have any of my old shop tools,boocks etc. but would suggest that you investigate the thread sizes in BROWNELL"S ENCYCLOPEDIA.
I seem to remember they listed the thread sizes for the screws and studs used in all makes models of fireamrs at the time of publicaton.

 

[Rich B.]

I no longer have any of my old shop tools,boocks etc. but would suggest that you investigate the thread sizes in BROWNELL"S ENCYCLOPEDIA.
I seem to remember they listed the thread sizes for the screws and studs used in all makes models of fireamrs at the time of publicaton.

Interesting sounding book; I've never heard of it. But not much help, as the M&P didn't use screw-in studs. They were pressed in. Brownell's just sent me their latest catalog, I'll see what they offer.

Thanks for the name of the book!

mayuhm, if you'd like to take a crack at 'measuring' the threads, I'd be happy to send them to you. Shoot me an email if you'd like to look at them.

A real concern I have is that even if I get the size and correct tap, the hole may be worn to the point that the threads won't be deep enough to hold the stud.

New oversize studs pressed in is starting to be a very attractive alternative to me.

Edit: Here's a pic of the three Numrich studs.

 

[Rich B.]

I'm reading over the entire thread, I may try a combination of mayuhm & paulj84003's ideas...Remove existing studs; circle-punch them with 'hole punch' style punches, then press them in again...

 

[dangt]

Possibly I missed something somewhere in the above posts but..........
YOur picture of gun and one stud look like my circa 1950 22 Combat Masterpiece. The studs ( actually, I only dealt with one, the trigger stud on that gun ) were not threaded but pressed and possibly brazed in place. I replaced the trigger stud with a non-threaded one when I refinished the gun, silver soldering it into the frame. The stud was not loose in the frame, but worn so badly the trigger had LOTS of slop side-to-side. If I remember correctly, the new stud was not tight at all so relied on the silver soldering to secure it.

I have studs from Numrich and can give you some measurements:

hammer stud .188-36

cyl. stop and rebound stud .104- ? (finer than 44, coarser than 48, so I assume it's probably 46,
not included on my thread gauge.)

trigger stud .119-44

All these studs I have have rather crude looking threads , viewed with magnification. Tops of threads are very much flattened, not radiused. I'm sure that actual tap major diameter would have to be several thousands larger than these parts to accomodate the pronounced flat tops (crests) of the threads. I nhave no clue if these are aftermarket made or maybe war-time S&W NOS.

Dan

 

[Velodogs]

Try giving the folks at Tombstone Grips a call. They recently helped me with some grip studs for a browning 10/71

 

[dangt]

I later found the original trigger stud that I replaced on the 5 screw K-22. The portion of it that presses into the frame measures .125" . At least that one location does NOT have enough material (not any material) to tap to the size of the older style thread-in stud.

Dan