Getting a CZ barrel opened up to 9 mm

dtknowles

Any idea what it would cost to get a 7.62 CZ 52 barrel bored and rifled for 9 mm. I don't need them to do the chamber just get me some 9 mm rifling. This is not for 9 mm Para/Luger. I will chamber for 9 mm Mauser Export (9 x 25) not to be confused with 9 x 25 Dillon. Its is not really 9 mm Mause Escort but the 7.62 x 25 opened up to 9 mm but it amounts to something similar. The available 9 mm barrels seem to have gone away. I have one in 9 Para/Luger and one I chambered to 9 mm Largo but there is still length in the magazine for a longer case. I don't want to give up one of my two current 9 mm barrels for this but I can't find another 9 mm barrel and there are a lot of 7.62 barrels around.

Tim

v35

Contact Norm Johnson in N.D. @ 701-448-9188.
I want to lengthen one or more 9mm Tok barrels to 38Super/9x23.
Is there much of an issue with a few tenths of chrome plate?

dtknowles

I don't remember where I got these directions but they give you a clue on how you can modify the chamber for 9 x 23.

I did a modification like this using a friends lathe and stock reamers. It works fine with 9 mm Largo.

Tim

1) Put a 9x23mm reamer in a lathe tailstock chuck and the barrel in the lathe headstock chuck and remove material with Sulfered cutting oil until a case will chamber with the pistols assembled.

2) Or, put a 9x23mm reamer in a drill chuck, and hold the drill chuck in the right hand and the barrel in the left hand, and give a twist of the wrist until as 9x23mm case will chamber.

3) Or, use a 115 piece drill set, a drill chuck, and two hands.
http://www.widell.com/drillsiz.html
As you can see, V drill will make a .3770" hole and a W drill will make a .3860" hole. The correct choice for lengthening the chamber is 25/64ths =.3906". This make the chamber .0060" sloppy, but that is fine.
The throat should be .357"
As you can see the T drill makes a .358" hole. that is .001" oversize
23/64 drill will make a .3594" hole, that is .0027" oversize.
U drill will make a .3680" hole, that is .011" oversize.
I find that I like the U drill better for getting the cartridge to fall in the chamber, but drill holes made with a twist of the wrist may be a few thousands small.
I seat a .358" LSWC bullet out to 1.36" and cut the throat until the cartridge falls in.

If you want 1.36" loads with 158 gr .357" and .358" bullets, then the 9x23mm reamer from Brownells is not going to do it all.

dtknowles

quote:Originally posted by v35
Contact Norm Johnson in N.D. @ 701-448-9188.
I want to lengthen one or more 9mm Tok barrels to 38Super/9x23.
Is there much of an issue with a few tenths of chrome plate?



Where is the chrome you are talking about. In the chamber you will be cutting into it if you rechamber to 9 x 23.

The Moron

9x25 would be too big for the CZ barrel, the chamber would be dangerously thin near the front. Most sources I've heard recommend chambering to nothing longer that a 9x21 since the chamber/roller arrangement was designed for a bottleneck cartridge

v35

I've heard CZ52 barrels let go, splitting the slide with hot 7,62x25s.
The failure takes place at the roller locking grooves. Not having one of these, I dont know how far from the breech end they are. At best you'd be thinning wall thickness by .023 by going to 9x19.
The chrome plate is in chamber and bore and can't be more than a few tenths thick.

dtknowles

v35, can you provide documentation on the barrel failures? I would like to know more. I have seen discussions of CZ-52 blowups that happen that were traced to a particular type of surplus ammo. My understanding was the barrel let go in the roller cam slot not the roller cuts.

The Revenge, can you please also provide sources or data about CZ-52's rechambered to 9 mm. I would like all the info I can get.

Thanks

Tim