Smith & Wesson Forum

Go Back   Smith & Wesson Forum > >

S&W-Smithing Maintenance, Repair, and Enhancement of Smith & Wesson and Other Firearms.


Reply
 
Thread Tools Display Modes
  #1  
Old 09-25-2021, 02:41 PM
glowe's Avatar
glowe glowe is offline
US Veteran

Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Nov 2009
Location: Michigan Western UP
Posts: 10,958
Likes: 1,917
Liked 9,940 Times in 4,128 Posts
Default Problems Replacing a 1930's K Frame Barrel

I am attempting to have a barrel changed on a 1930s K frame 38. My gunsmith is very capable and, so far, has removed the barrel from the frame and tried hand turning another 4th Change barrel into the frame. It went in 4 turns and I could not hand tighten it any further. He put the original barrel on the frame and could hand turn it 8 turns before it would no longer. Obviously, the old barrel was removed without issue using a wrench.

I started taking measurements to find that the old barrel thread OD measured .535” at the rear and .539” next to the barrel swell at the front of the threads. I then measured the replacement barrel and the thread OD measured .535” at the rear and .542” at the front. The only measurements I could take on the frame was the diameter of the “hole”, which would be inside peak to peak measurement. It came up at .510 at the rear (cylinder) and .520” at the front face of the frame.

Threads were cleaned before trying both barrels and done with light oil. The replacement barrel appears new and probably never installed on a gun, so my first question is if anyone knows how the factory fit barrels during manufacture? Standard threads appear to be .540” X 36tpi so if used would generate equal sized straight threads, but both barrels and the frame appear to have a taper? Which way is standard?

Most important is what suggestions do you all have in order to modify the new barrel to screw on without endangering the very thin bottom frame web? Any comments or suggestions are welcome. Any tips on how to fit up a new barrel to the frame would also be appreciated. It is understood that .540 taps and dies are not available today, so options seem limited.
__________________
Gary
SWCA 2515
Reply With Quote
The Following User Likes This Post:
  #2  
Old 09-25-2021, 05:06 PM
Protocall_Design Protocall_Design is offline
Vendor
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Jan 2010
Location: Kansas City area
Posts: 3,989
Likes: 22,055
Liked 7,193 Times in 2,545 Posts
Default

I have a .540 - 36 tap and die from Brownell's. That is still the standard K frame barrel thread size. If you run the tap thru the frame and the die on the barrel, they will fit together.

The sku# for the tap is #080-598-540WB

The sku# for the die is #080-598-541WB
__________________
Protocall Design
Reply With Quote
The Following 6 Users Like Post:
  #3  
Old 09-25-2021, 05:24 PM
2152hq 2152hq is offline
Member
Problems Replacing a 1930's K Frame Barrel  
Join Date: Sep 2005
Posts: 6,651
Likes: 1,045
Liked 6,324 Times in 2,547 Posts
Default

When they fit too tight upon assembly like that, I lap the threads in.
It doesn't take a lot of work and the process goes fairly quickly.

I've used the method on rifle bbl/action assembly threads as well as handguns.

Keep the frame and bbl wrapped in a protective covering to prevent the lapping compound grit from scratching the surfaces in the event that it gets on your fingers as you handle the parts.

Wash all the compound out of the threads when completed and before final assembly.

Use of the proper tap & die is much quicker and cleaner of course, but lapping the threads also works.
Reply With Quote
The Following 2 Users Like Post:
  #4  
Old 09-25-2021, 07:56 PM
glowe's Avatar
glowe glowe is offline
US Veteran

Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Nov 2009
Location: Michigan Western UP
Posts: 10,958
Likes: 1,917
Liked 9,940 Times in 4,128 Posts
Default

Quote:
Originally Posted by Protocall_Design View Post
I have a .540 - 36 tap and die from Brownell's.

The sku# for the tap is #080-598-540WB

The sku# for the die is #080-598-541WB
Thank you for those numbers. I had searched Brownells, but apparently could not come up with the right search terms to find the tap and die.

The old barrel measured under .540 and was tight. With an as new barrel that measures very close to .540", do you think that tapping the frame would all that is needed?
__________________
Gary
SWCA 2515
Reply With Quote
  #5  
Old 09-25-2021, 08:03 PM
glowe's Avatar
glowe glowe is offline
US Veteran

Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Nov 2009
Location: Michigan Western UP
Posts: 10,958
Likes: 1,917
Liked 9,940 Times in 4,128 Posts
Default

Quote:
Originally Posted by 2152hq View Post
When they fit too tight upon assembly like that, I lap the threads in.
It doesn't take a lot of work and the process goes fairly quickly . . .
Thank you for the advise. My gunsmith did mention this option and I will discuss further with him. I do think I might buy the tap, since the threads do not look perfect after the old barrel was taken out. Maybe lapping, if needed, will be easier with freshened threads in the frame.
__________________
Gary
SWCA 2515
Reply With Quote
The Following User Likes This Post:
  #6  
Old 09-26-2021, 12:16 AM
Llance's Avatar
Llance Llance is offline
US Veteran
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: May 2021
Location: Northwestern Illinois
Posts: 390
Likes: 354
Liked 596 Times in 252 Posts
Default

I would do a tap and die of both the barrel and the frame. That way there can be no question as to the proper fit. Or which item is not fit correctly.
Reply With Quote
The Following 3 Users Like Post:
  #7  
Old 09-26-2021, 01:31 AM
teletech teletech is offline
Member
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Feb 2014
Posts: 416
Likes: 43
Liked 416 Times in 185 Posts
Default

Quote:
Originally Posted by glowe View Post
Thank you for those numbers. I had searched Brownells, but apparently could not come up with the right search terms to find the tap and die.

The old barrel measured under .540 and was tight. With an as new barrel that measures very close to .540", do you think that tapping the frame would all that is needed?
Measuring the inner diameter of a tapped hole or outer diameter of a threaded shaft is almost completely meaningless from a machinist's point of view. You are most interested in the pitch diameter and secondarily the root diameter. An optical comparitor is a good choice, or you can use a specialty thread micrometer, but failing that you can use fine diameter pin gauges and a standard micrometer. If you don't have three small pin gauges the same diameter you can mostly get away with using a set of three drill bits of the same brand and lot. Actually, considering you want a wire that will touch in about the middle of the depth of the thread I suspect three ordinary sewing pins would work pretty well in this case. It will give you something for the sake of comparison at least that is far better than the major diameter.

All that said, assuming the frame wasn't damaged and the old barrel fit was good, If I were on a budget I'd just buy a die and run over the new barrel in the hopes that it will solve any problems since the frame did accommodate a barrel at least. If I weren't on a budget, then I'd buy both the tap and die and run them both. I'd much rather need a drop of locktite to keep them tight than to constrict the barrel and suffer poor accuracy as a result.

What is Pitch Diameter?
Reply With Quote
The Following 6 Users Like Post:
  #8  
Old 09-26-2021, 02:20 PM
glowe's Avatar
glowe glowe is offline
US Veteran

Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Nov 2009
Location: Michigan Western UP
Posts: 10,958
Likes: 1,917
Liked 9,940 Times in 4,128 Posts
Default

I just ordered the die as well. Already have a member who wants to buy the set from me when done if I do not want to hold on to them.

This approach takes all the variables out of other options, chase both frame and barrel to be safe and minimize the amount of stress placed on the lower frame where it is extremely thin. For those of you who have not seen a frame without the barrel attached, here it is. Scary thin.

Problems Replacing a 1930's K Frame Barrel-p1010001-jpg
Problems Replacing a 1930's K Frame Barrel-p1010002-jpg
Attached Images
File Type: jpg P1010001.jpg (70.7 KB, 210 views)
File Type: jpg P1010002.jpg (68.4 KB, 208 views)
__________________
Gary
SWCA 2515
Reply With Quote
The Following 4 Users Like Post:
  #9  
Old 09-26-2021, 08:19 PM
Kp321 Kp321 is offline
Member
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Aug 2018
Location: West Texas
Posts: 199
Likes: 45
Liked 117 Times in 79 Posts
Default

I am a big proponent of lapping threads is cases such as this. I would not use anything coarser than 2A grit on these fine threads.
Reply With Quote
The Following User Likes This Post:
  #10  
Old 10-03-2021, 10:54 AM
WR Moore WR Moore is offline
Member
 
Join Date: Oct 2006
Posts: 4,931
Likes: 528
Liked 3,295 Times in 1,688 Posts
Default

Post #7 mentions finding the pitch diameter. Decades ago I bought the proper wire gauges to do this for 36 tpi. The wires are 0.01605 in diameter (and it's a PITA to do). You aren't going to find drills that size. Plus, since the diameter of the barrel shank is an odd size, the only standard available is from measuring a barrel that properly fits a frame. When you do custom, you do trial fits on the frame when you get close to the measured diameter.

The tap & die are the way to go. A slight taper on the barrel shank isn't unusual for production barrels. I expect the shank/tenon was machined to size back then by using a shape tool that fed in at a right angle to the barrel blank. If the tool wasn't set up/ground exactly correct, there would be a slight taper. The parts inspectors had the tolerances to verify if it would be within specification.
Reply With Quote
  #11  
Old 10-03-2021, 11:07 AM
Jaco1234 Jaco1234 is offline
Member
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Apr 2019
Posts: 42
Likes: 8
Liked 30 Times in 17 Posts
Default

I would try lapping first.
Timesaver compound

Timesaver Lapping Compound Yellow Label and Green Label Compounds, non imbedding lapping compound, manufactured by Micro Surface - Newman Tools

I have not used this on a barrel, but have lapped many gears, bushings and pins with it.
Timesaver is fast and it is soft so over lapping is minimized.
Reply With Quote
  #12  
Old 10-03-2021, 05:05 PM
glowe's Avatar
glowe glowe is offline
US Veteran

Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Nov 2009
Location: Michigan Western UP
Posts: 10,958
Likes: 1,917
Liked 9,940 Times in 4,128 Posts
Default

Thanks all for your comments. I received the tap and die for K frame barrels post-1903 with the introduction of the Model 1902, 1st Change. The die was adjustable, so set it to cut the least as I could do. Could run it with my hand and a gripper pad. The tap is a straight die and fixed diameter at .540". Ran in smoothly and done in a couple minutes. I threaded the barrel on the frame and it was much better, but still did not turn in by hand, so set the die tighter and the second time was the charm.

What amazes me is that a near 100 year old gun can accept a random barrel without any further work required. First, the replacement barrel screwed in by hand smooth as glass until it was maybe 1/8 turn from top center. Wrenched it and it stopped exactly where is was supposed to. Measured the gap at .005" - perfect! The barrel aligned perfectly with the lug as well.

The replacement barrel already had a pin slot and I was not sure if it had been installed on a frame or not, but assumed that with the slot it must have been on another gun? I picked out a number drill bit smaller than the hole in the frame to check alignment and the bit dropped right through the hole - another perfect fit up. I am now of the opinion that the manufacture of barrels and frames were so precise that they milled the slot in the barrel prior to installation??
__________________
Gary
SWCA 2515
Reply With Quote
  #13  
Old 10-03-2021, 06:37 PM
Malamute Malamute is offline
Member
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: May 2004
Location: Northern Rockies
Posts: 101
Likes: 28
Liked 80 Times in 36 Posts
Default

Quote:
Originally Posted by glowe View Post
... I am now of the opinion that the manufacture of barrels and frames were so precise that they milled the slot in the barrel prior to installation??
I believe that is correct, all Ive seen were blued in the pin groove, and I believe Ive had some never used barrels and they were grooved already. I recall seeing pictures somewhere of many barrels on a rack ready to blue at the factory and they were already grooved.
Reply With Quote
The Following User Likes This Post:
  #14  
Old 10-03-2021, 08:49 PM
teletech teletech is offline
Member
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Feb 2014
Posts: 416
Likes: 43
Liked 416 Times in 185 Posts
Default

Quote:
Originally Posted by glowe View Post
I am now of the opinion that the manufacture of barrels and frames were so precise that they milled the slot in the barrel prior to installation??
They didn't have to be particularly precise in the pin slot, it needs to prevent rotation so the distance of the slot from the bore matters, but it could be almost any width and do it's job and they are cut a bit wide.
Usually you can rotate a barrel a degree or more without disturbing the pin, so it's not that precise there either.
I've actually seen a loose barrel where it could rotate several degrees until you hit the pin. It's a nice touch, but I can see why they discontinued the practice.
Reply With Quote
  #15  
Old 10-05-2021, 06:15 PM
WR Moore WR Moore is offline
Member
 
Join Date: Oct 2006
Posts: 4,931
Likes: 528
Liked 3,295 Times in 1,688 Posts
Default

Quote:
Originally Posted by glowe View Post
What amazes me is that a near 100 year old gun can accept a random barrel without any further work required. First, the replacement barrel screwed in by hand smooth as glass until it was maybe 1/8 turn from top center. Wrenched it and it stopped exactly where is was supposed to. Measured the gap at .005" - perfect! The barrel aligned perfectly with the lug as well.
Just saw this. You should have gone right out and bought a lottery ticket too!

Last edited by WR Moore; 10-05-2021 at 08:08 PM.
Reply With Quote
The Following User Likes This Post:
  #16  
Old 10-06-2021, 09:25 AM
fleabus101 fleabus101 is online now
SWCA Member
Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel Problems Replacing a 1930's K Frame Barrel  
Join Date: Dec 2018
Location: S W GA
Posts: 550
Likes: 1,997
Liked 1,078 Times in 290 Posts
Default

Im glad your barrel exchange worked out well
for you..It reminds me of the old adage..
The 6 P Principle...Proper Planning Prevents Piss
Poor Performance😁😁
It was drilled into folks by me and others at my
USMC work center building weapon stations(gun turrets) for our young Marines.
Always a joy when a plan comes together.
Best Randy..

Last edited by fleabus101; 10-06-2021 at 09:27 AM.
Reply With Quote
The Following User Likes This Post:
Reply

Thread Tools
Display Modes

Posting Rules
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
My 1930 to 1940 N-frame Wheel-of-S&W's 1blindref S&W Hand Ejectors: 1896 to 1961 21 03-17-2014 08:21 PM
Please close: WTB: 1930's - 40's 5 N frame holsters quinn WANTED to Buy 0 02-02-2014 12:13 AM
Replacing 686 Barrel Tripwire229 S&W-Smithing 10 07-29-2013 08:38 PM
L frame with barrel problems fulwood S&W Revolvers: 1980 to the Present 4 08-30-2012 07:20 PM
Replacing barrel on 686-3 where would you have it done? Revolver King S&W-Smithing 1 06-18-2009 06:48 PM

Powered by vBadvanced CMPS v3.2.3
smith-wessonforum.com tested by Norton Internet Security smith-wessonforum.com tested by McAfee Internet Security

All times are GMT -4. The time now is 03:15 AM.


Search Engine Optimisation provided by DragonByte SEO v2.0.42 (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Smith-WessonForum.com is not affiliated with Smith & Wesson Holding Corporation (NASDAQ Global Select: SWHC)