Original Winchester 66 breech block

[Wombat3]

Hi All
My Question is can a original Winchester 73 breech block be machined to 66 specs?

[DJ]

No expert here, but I tried a repro '73 in an original '66 and it took a bunch of filing and fitting, but I don't think I put it in the mill. 

What are you contemplating?  Because the firing pin retention system is different, and you'll end up with a gap where the firing pin retractor goes.

--DJ

[Wombat3]

Yes I’m no expert either. I have a 66 that is missing some parts, and 66 parts here in Australia are rare as rocking horse pop.  I have contacted some USA reproduction parts people but there unwilling to ship to Australia.
I have a spare 73 breech block and was hoping I could get some one to machine it to fit.  I would also have to get a piston and striker made for it as well. I have a spare set of 73 toggle links not sure if they will work in the 66 . Any advice anyone can give I would be very grateful.

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[DJ]

I may be mistaken, but I think the repro 1866 and 1873 breechblocks may be the same or very close to one another--I don't think the modern factories followed the original '66 design that closely.  Regarding the block I toyed with, I  recall that the original '66 had some squared off corners where they were rounded off on the repro block.  I don't know if that would affect function or not. 

If you're making a shooter (rather than a non-gun), the retention of the firing pin/piston presents a complication.  The '73 relies on the back end of the extractor (held by a very small pin), the firing pin retractor (held by a medium sized pin), and the weight of the hammer (held by the force of the hammer spring) to keep the piston from coming out the back of the gun.  The '66 uses the screw-on firing pin (a two-pronged "crown" held by the threads), the rear of the extractor (held by a very small pin), and the weight of the hammer (held by the force of the hammer spring)  to keep the piston from coming out (into your face).  If you install a '73 bolt without figuring out how to make the firing pin retractor work in that gun, you lose the main structural pin holding the piston in the gun without gaining the additional strength of the screw-on firing pin.  Definitely a safety consideration you would want to explore carefully, because a piston embedded in one's cheek can ruin the looks of even the prettiest face.

There was a thread a few years ago on a centerfire conversion I did using the original bolt.  That might not help you much, but it does have photos of some of the components you might be missing and could give you some ideas.

https://www.cascity.com/forumhall/index.php?topic=60404.msg718894#msg718894

In sum, I think a '73 repro bolt could be made to fit, but if  you want to shoot it there are other design considerations besides getting it into the receiver and making it go back and forth with the lever.

Sorry I couldn't be more help, but perhaps others with more experience will chime in.

--DJ
(edited right away to correct two silly mistakes)

[Wombat3]

Thankyou DJ that is very good information . The Gun will definitely be a non shooter I would just like it as original as possible and be complete and able to work the action . Before  this thread I googled Winchester 66 breech block and then images and your photos of the Center fire conversion were there , there was no text just the photos.
The link will be very helpful. Thanks

[DJ]

I don't know about an original '73 block, but if all you're looking for is an approximation, you should be able to use an Uberti Henry block.  I bought one of those several years ago from S&S Firearms  and was able to fit it to my '66 with some judicious sanding and filing.  That block is pictured in the centerfire conversion thread.  Uberti used a '73 style extractor, so that would have to be ground down to allow the bolt to seat all the way forward.  Also, the main body was just a little oversized but not so large as to require mechanical cutting tools.  To approximate the '66 firing pin system you would need to drill out the solid bolt face and then countersink it from the front to take the round, female-threaded firing pin crown.  You'd have to make the firing pin crown either from scratch or out of a nut.  For your piston you'd need a correct diameter drill rod contoured to fit through the hole in the back of the receiver, reduced in diameter as necessary to fit inside the bolt, and male-threaded to accept the firing pin.  Don't forget you must remove the extractor and then cut a semicircular notch in the top of the piston that is sized so as to permit a little back-and-forth movement for the firing pin stroke.  For even more authenticity, cut a slot at 3:00 and 9:00 o'clock in the face of your bolt, and when you shape the firing pin crown out of a nut, make sure to leave two "ears" at 3:00 and 9:00 to match the slots in the bolt face.  You may also have to alter or replace the pins that connect the toggles to the block, but that is only a minor alteration--I believe that pin is larger than the original, so I made mine with thin ends to fit the toggles and larger center section to fit the breechblock. 

Of course this all assumes the design and dimensions of the Henry centerfire breechblock have not changed over the past 15 or 20 years since I bought mine.  I don't know off hand whether an original '73 breechblock is the same size, but if so the alterations would be about the same.

The machinist you're planning to use is a really good friend, right?  Otherwise, I do see '66 breechblocks on ebay or Gunbroker once in awhile for about $250 to $300, which might save some effort and might even be cheaper.

Good luck!

--DJ

[Wombat3]

Thankyou again DJ
I think your reply has covered everything I need. The friend I have in mind for the job  has the attention to detail and only perfection will do gene , he also has gun oil in his veins so I’m lucky in that regard. I may need to go to some gun shows here when the covid 19 thing passes  . I saw some 66 parts on USA eBay  I contacted the seller EBay  would not allow him sell outside USA . Rules must have changed I have got parts from him 5 years ago for a 73 and a 90. I will keep you posted on the project.
WOW  read through your thread on the Center fire conversion.

[Pettifogger]

Are you talking about a real WINCHESTER 66 or a Uberti knockoff?  The bolt on an original 66 is shorter than an original 73 by almost 1/4".  I.e., the difference in length between the .44 Henry Flat and the .44-40.  The bolt, the firing pin, the carrier, the lifter arm, and the toggles are all longer on a Winchester 73.

[Wombat3]

Yes a real 66.I have a lifter and cairrer arm and none of the rest you mentioned, are the diamentions similar other than length and the cut out for the 73 fireing pin retractor also the bolt face on the 73 bolt to the 66 bolt?