Tuning Ideas to Repair Stripped Out Treads in Vintage Crosman 101 Appreciated

[c801tfd]

A couple of weekends ago I decided to work on a recently purchased Crosman 101 with Straight Logo dating to about 1925 – 1927 had bronze compression tube and rifled steel barrel. The seller informed me it did not pump up or hold air and was hard to cock. I was so excited to find one of these locally and was glad to pay just $100.00 after some negotiation based upon sellers verbal description of condition.

During the purchase, I noticed the cocking knob moved a lot, what he did not tell me was the trigger sear was neaarly the only thing holding the valve and cocking assembly in the breech block. I discovered this issue when I tried to cock it and upoin pulling back on the knob I had the valve, lock nut and cocking assempbly in my hand, from there I decided it was time to strip it down and figure out what was going on. 

I thought maybe just maybe it had been taken apart and not put back together. Sadly this is when I discovered the the treaded area in the breech block were what you can consider gone as there is nothing left to retrace, which puts this project in a bad place at the moment.

I have a few radical ideas on making the repair such as puting it back together in a similar fasion as how the old Rochesters were assemeble with the valve being assembly soldered to the compression tube. I know I can do this but any future repairs that may be needed become a real pain to do, or I can do a soldered valve approach knowing I would need to take the gun down from both sides if reapirs to seals are needed. However, before gettting radical I took the breech block and lock nut to a local gunsmith, he told me that he did not have the means to work on this and suggested using JB Weld since this was not a high torque area or function then tap/retrace the threads from the compression tube side of the action.

I am not sure about the JB Weld solution and before I get to radical or start looking for another straight logo gun I would really like to find out if others have had this problem and how the repair was made in those instances.

Here’s hoping someone out here has some tips or advise to help save a classic from being a visual example of what once was, if not I all I can say is it is my $100.00 lesson learned, or who knows maybe JB Weld or one of my radical solutions will be attempted and if it fails I may just have $100 worth of parts for the next one I find.

Regards

General Diagram of a 101 disregard years as basic components are the same as the older 101s, just newer ones have updated/improved parts: 

Problem area is as follows:

Breech block (101-48) the interior female treads on this part are stripped so body lock nut (101-15) will not hold exhaust body (121-5) in place and comes out when up cock the gun (hammer assembly) parts: Hammer sleeve (101-39, Hammer Spring (101-8) Hammer Spring Lock (101-5, scres onto stem of exhaust body 121-5) and Hammer Plug (121-15). Due to stripped out breech block threads all of this comes out when cocking.

 

[rangur1]

Just a guess , but what is possibility of rethreading the female threads? Using a tap and die ? then maybe the body lock nut can grip it with teflon or similar tape added to make up the difference created from re tapping it. Or even a slightly bigger locking nut? this is just a theoretical idea , 

 

[c801tfd]

rangur1, 



All ideas are welcome, I am playing with the idea of asking a machine shop if it could be done for a reasonable price to add slightly larger more common threads and making a new lock nut just because of the challenge to find a suitable repair. If it costs to much it may be more economical to find/purchase a donor breech block. 

Oh the fun of the vintage world

 

[GeneT]

Someone with a lathe is your best bet. If there's enough meat in the breech block you could have a custom insert made, but the cost would probably exceed your $100 investment. I'm typically skeptical of glue jobs, but it might be the most practical option if you want to keep your investment in the same ballpark.

GsG

 

[c801tfd]

GeneT, 

When working on old air rifles I really do try to stay within a monetary parameter. Usually I tell myself not to go over what the average price of working version is valued at, please keep in mind I do this not for resale purposes, what I own I keep, I just use value to determine what I will consider spending to bring a vintage rifle back to life for my own use. With that in mind if it cannot be done for a resonable price then glue/epoxy it shall be, after that the search for a better version will begin in time.

 

[rc4fun]

If there is enough thickness you can use a heli-coil. I have used them in plastic, steel and aluminum. They do work best on non-through holes. For through holes threaded inserts (such as rivet nuts) work but you need some clearance on the inner side.

A completely re-threaded hole the next size up may work too.

 

[biohazardman]

Yup next size up is a pretty standard thing to do. You can put the bigger screw needed in a drill chuck and spin it and hold a file to the head to make it the right size and shape.

 

[Thatdarncat]

Hi,

I have seen a lot of this kinda stuff as a tool and die maker over the years till my recent retirement. There are several ways to approach it. I would stay away from epoxies and JB weld.

Without seeing it, the best answer would probably be to put a solid threaded plug after enlarging the hole and retapping it to probably some fine thread into it and screwing a the plug into it and them drilling and tapping that threaded plug to the thread size you need...If that area can stand some heat around 1200F, you could silver solder a liner in the hole ( after enlarging it) and then tap the ID of the liner to the thread size you need. But unless you have a mill, or know someone who does it might cost a penny or two, a machine shop would probably knock it out in 45 mins or less but your 100 dollar air rilfe is now a 200-250 dollar air rifle.

Back in the 90's when I made rifle barrels I used the button method and the pull rod for the carbide button but the only way I could secure the pull rod without snapping it was by drilling and reaming the pullrod holder to the pullrod size and where upon I would intersect 1/3 the diameter of the pull rod at a right angle through the pullrod holder and insert a dowel pin. with no gaps or play. Button rifling always " chokes" the end of the barrel on exiting...lol I get tickled at what folks call a choked barrels, like its something special...it just a natural process of the button rifling method...sorry for going off on a tangent...but it does have an application possibly for you here. 

So, if you cant put any heat on it for a liner, you could still place a liner in it and intersect the outside edge of the liner at a right angle to install a small roll pin or better yet a solid dowel with enough length poking out to later work it down flush to where it wouldnt even leave a witness mark and still have the liner trapped firmly in place,

The quick and dirty method would be to drill and tap the hole another size where the root diameter of the threaded hole would be large enough so that the screw that gets drilled and tapped is of course smaller on its outside diameter than the before mentioned root diameter.

What you need is a friend who knows how to efficiently operate a milling machine who would do this as a favor for you, It sounds easy enough to fix but the rub is you need a milling machine and a lathe

There are other things like heli-coil, keen-serts but they probably would work in you application due to a funky thread size...by the way what is the thread size ( diameter and thread pitch) of that stripped hole? Can you get it off of the screw that went in there? There might be a remote possibility that a Keen-sert may have the size you need

 

[OTmachine]

In the past, I have made an oversized bolt on the lathe, with the same threads per inch. Gash the threaded section perpendicular to the threads in 3 places, equally spaced to make a tap. Since this is soft metal, this will work to clean up the threads oversized. I would leave enough of the oversized threaded bolt without gashes to cut off and fashion a new oversized body lock nut. I have done this successfully on a Challenger Arms Plainsman. I think the body lock nut is 3/4-24 on your 101. So, in this case I would make the tap and new nut about .790-24. This would remove a minimal amount of metal. HTH.

Keith

But, it depends on if you have enough room on the inside diameter to put an oversized tap in there.

If I get a chance I will measure it up and let you know.

 

[c801tfd]

Thatdarncat, 

Thank you for the ideas, I have time to work with so making a decision based upon best approach is developing with each comment. 

 

[c801tfd]

OTmachine, 

What you have described is a fix I have thought about a few times but had all but given up on as no one I showed the original lock nut threads to could identify the thread needed. As you indicated the diameter is 3/4 inch. Your confirmation of measurements would be very helpful and greatly appreciated as this is something I know I can do once I know correct measurements to look for.

 

[OTmachine]

And the fabricated bolt body above the tap end should be about the same size as the bore it is going into which would make it self aligning to guarantee that the threads go in straight. Is there any trace of the original threads left? This would help to reduce the O.D. of the fabricated tap. I am taking measurements off of a 1949 101 as of now. I have a Disk Applied 101 I can possibly check to confirm. Possibly tonight, as I have to work now.

 

[c801tfd]

Sadly, the threads are what one would call worn smooth, you can only see lines of what used to be, no ridge/grooves at all left in the breech block but the nut is good..

 

[Ripper]

Being in machining and tool and die I have to agree with some of the other guys that Tapping it to the next size and making a plug that will screw in there with a threaded internal thread of the size you need would be the best way to go. Or you could just bore it out like one guy said and press it in there also.It would actually be stronger than original using better material.No it wouldn’t be cheap. I used to do things like that for people for free. I’m retired and don’t have access to Machinery Anymore.

 

[OTmachine]

Looks like you have plenty of room to tap a new thread size. The bore diameter before the stripped out threads on my 1949 is about .820 inch inside diameter. M20 x 1.0 tap would work good, (20mm = .7875 inch). 1.0 mm thread pitch is about 25 threads per inch, so it would be comparable to the original 24 tpi. It would be best to make an .815” diameter guide bushing for the shank of the tap to keep it straight. You would also need to get an M20 x 1.0 bolt to make the new nut out of. My .02

 

[c801tfd]

OTmachine,

Thank you for taking the time to provide me with information to make proper repair, one day I hope to return the favor. It may take me a month or two to get this one up and running but now I can knowing the fix will last for a long run.



Ripper,

Thank you for the affirmation of repair concept, AGN community is great when it comes to helping find solutions.

 

[OTmachine]

C801tfd, Glad that you are getting it sorted out and that the forum could help.

Regards,

Keith

 

[c801tfd]

Proud to say no JB Weld or other epoxy solution used to make needed repair and my vintage Straight Logo Crosman 101 will return to shooting condition soon.

Thanks to OTmachime (Keith) and Ripper and others I was able to pull off a satisfactory permanent repair that will keep this rifle shooting for another 100 years once I get the seal kit with conical seal and new compression chamber with seal groove cut into it. I will buy the parts to upgrade the pump seal from the old leather setup it currently has.

Here are some pictures of the repaired threads for the lock nut. Since I have no machinery the lock nut with updated treads was hand fabricated and using a 20M brass bushing and press fitting and soldering the original lock nut inside of the bushing after filing it to fit the ID of the brass bushing. 

 

[OTmachine]

Congratulations! Looks like you got it. Good work!

 

[Wadcutter]

c801tfd,

Am I wrong in thinking you cut threads at the rear of the receiver? Why...? The factory threaded area is at the front of the receiver and extends just past the transfer port. It's only about 1 1/4" in length and does not get into the trigger slot. If you're plan is to run that enlarged nut all the way up to seat the valve guide, it's not going to work. As I mentioned on the other forum, the pellet logo models, like in example photos below, had a steel threaded insert cast into the receiver. Straight Logo 101's lack the insert, but the threaded area is the same on both, 3/4-27.

The attached photos show that the threaded sleeve is smaller diameter than the rear of the receiver where the valve parts are inserted. Notice the edge in bottom photo where the factory threads start. Your modified nut is too large and will hit that ledge and prevent any further tightening. You also can not make the factory threaded area larger because of the valve guide diameter and also the pump tube size.

Are you sure the factory threads are stripped? Maybe a previous owner just stuffed the parts in there to keep them together without screwing the valve nut down, and the threads are actually still good. Try running a factory unmolested valve nut down the threads from the rear without any components installed. If it doesn't easily start, don't force it, just come in from the front side where the pump tube screws in. The threaded portion is only about 1 1/4" long, so run the nut all the way through till it falls out the back. That steel nut will help clean and reform the zinc alloy threads if they are buggered. If the factory threads are truly stripped, then you will have to slightly bore the front end out and machine a threaded insert for it. Once again, the threads are 3/4-27.