Converting original 1866 to center fire

[DJ]

I have an 1866 I would like to shoot and was wondering if anyone has converted an original to center fire.  Before I ruffle any feathers, let me say that I have acquired a spare original bolt with extractor and firing pin as well as spare firing pin extension ("piston"), so at most I am looking to modify spare parts rather than the originals that came in the gun.

What I'm interested in is the technique used for the conversion.  Unlike an 1973, which has a flat bolt face with a hole in it for the firing pin, the '66 bolt has a fairly large hole bored all the way through, and the firing pin extension also acts as a substantial part of the bolt face.  The two ideas that come to mind are to plug the face of the bolt and then run a firing pin through the plug or to shorten the firing pin extension and build a new center-fire pin similar to the existing rimfire pin.  The latter would have the benefit of reducing or eliminating modifications to my existing spare parts.  But I am concerned about headspace and primers maybe backing out if more than half the surface of the bolt face can move back several thousandths of an inch under recoil.  I've never heard of that being a problem in the original design, but I wonder if a separate primer would make it an issue.

The '73 is on the left in each of the first two photos (yes, it's an Uberti, but will suffice for my purposes) and the '66 is on the right.  The third photo shows the '66 bolt and the removed ignition assembly. (original post was modified to add photos and descriptions of photos).

If you have experience or insights regarding this conversion I would appreciate hearing back.

Thanks--

--DJ

[Tuolumne Lawman]

About 20 years ago, a CAS City member named Charley Gullet created a centerfire 1866.  It all started with a relic 1866 receiver and lifter I sent him, crusted in the rusty remains of the barrel and innards.  He submerged it in some kind of acid that attacked the rust, but left the bronze (gunmetal) receiver and lifter intact.  He used heavily modified 1873 parts, except the barrel, which was an original 1866 barrel.  He used 41 Magnum brass to fabricate the cases, and had a special heeled bullet mold made .442" for the bore.

I do not remember any more details, and Charley dropped out of CAS around 12-15 years ago.  It was a slick little weapon and a real show stopper.

Around the same time Charley did his, I knew another shooter that had an original 1866 Center Fire.  He used a different case for the round, something like a 41 Colt.

[Tuolumne Lawman]

I just had a flash.  Charley published one or two books on CAS, and I believe they had his contact info and real name in the covers.  I don't think I still have mine, but some long time member might have a copy and could check for you.  

Hey Coffinmaker, do you have a copy?  You were in the posse back then.

[Coal Creek Griff]

I did a little checking.  Charly is associated with Warfield Press in Prescott.  Their contact info is on their website,  in case it helps.

  http://www.warfieldpress.com/   

CC Griff

[Coffinmaker]

Hi Guys,

I remember Charley converting that rifle, and I know of his books.  Unfortunately, I don't have a copy.  I also don't remember exactly how he converted the '66.  Had I both an original 1866 and an original 1873 and a pile of spare parts and my machine tools back inna shop, it would be a fun project.  Twould require some modified cartridge cases as well.

What I wouldn't give for a few thousand new manufacture 44 Henry Flat cartridges.  Then I'd also need an original '66 and a pair of original 1872 Open Top pistols.  Take that all you "Period Correct" posers.  O Odin hear my want!!!!

[Mike]

I believe there was a 66 bolt that had rim and center fire pins, with out getting my book out to confirm this. will look tonight.

[DJ]

I decided I will play around with it for awhile and see what I come up with.  I'm planning to make new parts rather than alter the spare originals I have, because I don't think it will be that much more work and that way I can save the originals for a later project.

I started today by roughing out the firing pin extension/piston from a piece of 3/8" drill rod.  I left it long, because I still haven't decided how I will adapt it to centerfire. 

Does anyone know what the threads on an original piston measure?  I come up with .217 major diameter and 40 threads per inch, which seems pretty close to #5 NC.  CORRECTION:  close to #12, and an extra-fine thread, nonstandard thread, too.  Don't know how I got #5.  Anyway, not a size you see everyday, but sometimes Ebay seems to have everything.

[dusty texian]

Hello DJ, If you look at page # 29 in Arthur Pirkle s book ( Winchester Lever Action Repeating Firearms ) Volume 1 you will see figure 1-38 the striker for rim fire and the striker for center fire .A short description says that the Winchester factory made the change from rim to center fire by replacing the striker only, with a center fire projection , some had both rim fire and center fire projections . A very simple conversion.  If I could I would post a pic. of the drawing  but am not able to post pics at this time  PS . an old friend of mine that lived out his life near the Rio Grande and Old Mexico , both sides, had a center fire Model 66 Winchester that came up from Old Mexico . He shot it at times was a cool old carbine , had a rifle style butt . He has recently passed and left me his old 1876 Heavy Barrel rifle . Not sure who got the 66  . ,,,DT

[DJ]

Hey DT--

Thanks for the suggestion--I don't know how I missed looking at Pirkle's book.  As you can kind of see from his diagram (which becomes immediately apparent when you open one up), the 1866 does not really have a bolt face the way 1873s and most other firearms do--with the 1866 the edge of the bolt acts as part of the bolt face, the circular striker/firing pin acts as an "inner circle" of the bolt face, and the firing pin extension/piston acts as the center of the bolt face.  In an original, the striker and the extension/piston are free to move back and forth a few thousandths, and I am curious if that will allow centerfire primers to back out (and what effect that might have, if any).  

Helpfully, Pirkle explains that the centerfire modification involved replacing or modifying the rimfire striker/firing pin and then adding a central firing pin to the firing pin extension/piston.  What is not obvious from his description is that the firing pin extension/piston forms part of the support for the case head when fired and there consequently is no room to simply add a centerfire striker without either making it part of the piston or shortening the piston.  I decided to hold off on modifying the original spare parts I acquired at least until I work out the best solution, and am working on a reproduction piston/striker to fit the original bolt.  Of course everything is stalled for now, because I didn't have a tap and die set of the right size, although they are now supposedly en route.

Again, thanks for the pointer to Pirkle's book as I had completely missed it, and it at least validates some of my process.

Best--
--DJ

[dusty texian]

DJ , I did read in Pirkles book that frontier gunsmith conversions  were done by adding the center fire pin to the striker  ( Note the firing pin looks to be very wide at its base ) for helping keep the primer in place upon firing ? . I did not see where he mentioned the shortening of the piston , but can see where that may be necessary . I think if I were doing a conversion on an original as you are doing , I would make a new piston and striker  doing so would eliminate the need to use the exact thread as the original. A very interesting project . Will be on standby waiting to see your progress. Good Luck ,,,DT

[DJ]

Hey DT--

Thanks for your interest and good words.

I'm waiting on the tap and die, because I needed a size smaller than 1/4-28 and I was afraid that the next step down in my toolbox (#10-32) would be too small and easily bent or broken.  #12-40 is pretty much obsolete, but it falls about in the middle between the other two and is very close to the original in size.  Major diameter of 1/4 is .250, #10 is .190, and #12 is .216.  I suspect there is a metric size that might have worked, but call it superstition or whatever you like, I just couldn't bring myself to put metric threads in an original 1866 Winchester.

As far as shortening the piston, Pirkle does not mention it, but the way the end of the piston fits flush with the seat for the cartridge (or the three-piece bolt face, if you prefer), there really isn't room to thread a centerfire striker in there.  It works with the original rimfire striker, because the "pins" that hit the cartridge are to the sides, and the center is open for the piston to thread into.

Once I'm back  up and running I will try to post photos of what did and didn't work.

--DJ

(modfied 12/12/17 to correct silly typo)

[nativeshootist]

I was thinking about if anyone did this recently, seems like a cool project, I had the same idea except vice versa and make a rimfire bolt for a uberti and go from there. Can't wait to see the final product.


here's a link to a mold for .44 henry flat https://oldwestbulletmoulds.com/products/44-henry-flat-200gr-heel-double-cavity-mould
and a link to a video on making .44 S&W american but its basically the same as .44 henry center fire

[dusty texian]

Hey DJ , if you look at ( The Winchester Book ) by George Madis    Page 100 has a very good picture of the breech bolt faces of Rimfire and Centerfire botl faces . The standard rimfire striker ,,, the modified centerfire  striker and the factory centerfire striker . I cant post pics now . If you need , I can E-mail you a picture . Let me know ,,,,DT

[nativeshootist]

Here's a video of a center fire conversion on a Henry, its a very small snippet so might not be helpful https://youtu.be/ofGnRSE7lpI?t=13m59s

[DJ]

Thanks DT and Nativeshooter for pointers to the photos and video.  They should be helpful as I progress.  I will probably start with the version that uses the rimfire striker with the pins ground down and will make a new piston that is center drilled for a central firing pin.  The alternative, where a bolt face is threaded into the original bolt is interesting, although I will probably hold off on cutting my (spare) original bolt until I see if the first effort works.  I also wonder what was used to keep the piston from exiting through the back of the bolt in the event of a ruptured primer--in the original, there is the threaded striker that stops against a shoulder in the bolt, plus the piston is notched in the top and the back of the extractor keeps it from going back too far.  With the screwed-in bolt face, only the back end of the extractor holds the piston in the bolt.  

As a backup plan I have been working on an 1866 Uberti bolt to see if I can make that work--lots of fitting so far.  Interestingly, the Uberti 1866 bolt seems to be about the same as their 1873 bolt.

I have been tracking the tap and die I have been waiting on--they processed through Nanking on December 5th and through Los Angeles on December 15--maybe here by Christmas??  C'mon Santa, you can do this.

--DJ
(mod 12/18 to fix typo)

[nativeshootist]

Hey DJ, you get your tap and dies yet?

[DJ]

In a word, "yes."  Not sure when they arrived, but they were somehow intercepted and became a gift-wrapped item under the tree that I didn't open until yesterday.  With the family together I didn't have much alone time in the shop, but yesterday I did sneak out briefly and thread the end of the firing pin piston.  The die cut really well and leaves some pretty sharp V threads.  I'm anxious to see how they fit with threads cut by the tap.

I still have some "best design" issues I'm working on--may end up with an "original" and two "improved" designs to try out.  The construction of the 1866 bolt is odd--I had no idea what it was like until I tore apart an original to discover there is no bolt face.

Anyway, I won't have much time on it this week, but next weekend should find me at work on it.

--DJ

[modified to add photos]

[nativeshootist]

Seeing that you have a lathe, couldn't you use a big piece of drill rod and make a hand fitted part to replace the snapper? then you could make it into a workable bolt face.

[DJ]

If you don't want to alter the original bolt, it's a little more complicated than just making a new striker.  The bolt face of the 1866 is made up of three parts--the edge of the bolt, the threaded (internal threads) ring that carries the double rimfire strikers, and the threaded (external threads) striker that screws into the ring. Because of a "shelf" in the front end of the bolt, and the way the bolt fits into the receiver, the piston has to enter through the rear of the bolt, but the bolt face has to enter from the front.  When the hammer hits the back of the piston, it drives the piston and the attached collar with the rimfire pins (which are shaped like little wedges) forward.

I've attached a photo of the three components--you can see the little "shelf" inside the front end of the bolt.  The other two photos show the rimifire firing pins in the extended and retracted positions.  There is very little movement--around 0.030 inches.  Note also how the center of the bolt face moves forward when the firing pins move forward so the bolt face is then flat, although the only thing holding the center part forward is the hammer plus a little bit of inertia and friction. 

Also of interest--when the chamber is loaded the firing pins are resting against the case, and there is no spring force or safety device to prevent the piston from moving forward.  I have not heard of accidental firings, or slam-fires with 1866 Winchesters, but I would think it would be a fairly common event the way it's designed.

[DJ]

I had a little time in the shop this weekend and played with a couple possible methods for a conversion.  The first is similar to what it looks like contemporary gunsmiths might have tried--add a firing pin to the end of the piston and grind off the rimfire strikers from the collar, except I made a new piston and collar.  I still need to add some kind of "ears" to the collar to go in the slots at the head of the bolt--they are necessary to keep the collar from turning while screwing and unscrewing the piston.  Eventually I need to figure out the correct shape and length of the central firing pin, bearing in mind that it will be resting against the primer whenever there is a round in the chamber, so don't want it too long and pointed.  I think it's still a little too long, and I left it thick and rounded thus far.