chipmaker wrote on Nov 3^rd, 2021 at 1:04pm:

It might help if you looked for "J. Bunch", since that's what's stamped on the barrel.

Try to get copies of Michael Petrov's two volume study of 20th century custom gun makers.  They're rather expensive to buy, but a shooting friend might have them or perhaps you can obtain them through inter-library loan.

Bill Lawrence

Lot of “J Bunch” hits on Ancestry.com.  Figuring out which one is connected to your gun would take a lot of work & luck. Could focus on likely birth date,  someone who would build a rifle like yours. Probably 1900 or later & before 1950

Another separation could be place Mr Bunch lived. Look for Varmint Rifle use locations. Luck would be finding a Bunch with a trade that is linked to gunsmiths in obituary’s 

Boats

Having worked on CPA's with through bolts the mortice has gone all the way to the face of the action. When putting a white piece of paper under the action in this area I have been able to clearly see light on both sides of the action. From the back of the tang all the way back to the actions frame. The only contact points left are two very small cheeks on each that are just barely contacting the frame. The issues that I have worked on personally is this created and issue with the triggers actually working or not. If the through bolt is to tight they tend not work and if backed off until they do now work the contact points at the back of the action are no longer tight enough. And that now becomes a swivel point and accuracy is now non obtainable. But there is a real fine line when everything will actually work, no more swivel point and double sets will now work. What I believe is actually taking place is the bottom tang is being flexed just enough for the entire trigger group to no longer work as was originally designed. I might also add that I have personally worked on more than one having this same issue. And all though there are four screws, two on each side attaching the bottom tang to the frame it can still flex enough for the triggers to no longer work. These were also just after CPA offered a through bolt option and I don't know if they have since changed that original design. 

In cleaning up the action, I discovered that the serial number was stamped on the extractor. There was also the initials TR engraved/stamped on the other side.
Does anyone know who TR was?
Otto 

Ss
Thanks for your input. I was unaware that the serial numbers and caliber were stamped on Steven's extractors.
I'll check the other parts for serial numbers as I clean them. Do you know of any additional action parts that might have a serial number?
Yes. The breech block does look as if it was converted from rim fire to center fire. The firing pin was also reduced to .062".
The main issue now is removal of the barrel, which is super tight and might have some epoxy or Loctite in the threads.
Otto

Unfortunately I don't have any pictures to share on hand. On one of the rifles the contact points / stock to action on side was not touching the back of action. The mortice cut from back of action to back of tang. Left very little as  contact / bearing points. And to the point of allowing the wood to per-say warped and no longer being straight with the tangs. I don't recall the rear contact of the back of the tangs to the stock. It is typically an area of having no direct contact to minimize possible wood splitting. My own CPA uses the tang screws and both tangs and the contact points at the face of the back of the action have been fully epoxy bedded. This has also improved accuracy and the screws also put forward pressure towards the action when tightened. I also replaced the tapered tang screws that had a tendency to back out with straight shanked screws with very course threads and that has eliminated that issue.  The end result is there is now no flex between stock and action or a means for possible movement. 
I hope that helps to answer your questions and the original barrel a 32-40 has 140'000+ bullets down the bore. And there has been damage caused to the stock by having the back of the tangs being in hard and direct contact with the stock.

Chipmaker, the extractors are not always stamped with a serial number or caliber, but often are. As far as serial numbers being stamped on other parts, I have only seen the buttplate stamped, and sometimes you can see the serial number written in pencil on the butt end of the stock, and the barrel channel of the forearm.
Sometimes 44 1/2 rimfire breech blocks are stamped with the caliber, usually just a 22,25, or 32. 

As you can see only one of the loose extractors I had laying around had been stamped with the serial number, but all were stamped with the caliber.