Author Topic: 7.9x33 question  (Read 5882 times)

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Rolling Stone

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7.9x33 question
« on: January 31, 2013, 06:24:03 pm »
Have any of you ever tried to reload 7.92x33 (8mm Kurz)? The parent case for this is 30-06 and the case is shortened to 1.300. This looks like it would be a natural, using a .45ACP shell plate. Finding or re-making a sizing die and bullet seating die look like would be the hardest part. FC60 (Dave) have you ever done anything like this. I have Hornady dies already but the size of the ID and OD may be to close for a rework to 11/16". I'm not interested in original factory appearance. I just want them to work.  To start with I will be using Hornady 125gr jacketed HP bullets. Maybe someone has a 7/8" tapped Universal head they would sell fat a bargain, if the die will clear the casting. Even if only the sizer was 7/8". Anyone have any ideas on this? Will a 5/8 powder slide drop 22-23 gains of IMR 4198? Inquiring minds want to know.
Thanks all
Rolling Stone

fc60

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Re: 7.9x33 question
« Reply #1 on: February 01, 2013, 11:49:20 am »
Greetings,

The bottle-neck case is not suited for sizing on the Star, in my opinion. One could size the brass on a single stage press, then run it through the Star for priming, powder dispensing, seating, and crimping.

I do not see SAAMI drawings for the 7.9x33 cartridge.

Modifying existing dies or machining new ones from scratch would take some thought.

Cheers,

Dave

Rolling Stone

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Re: 7.9x33 question
« Reply #2 on: February 01, 2013, 05:53:22 pm »
Here is the best picture/drawing I could find.

rbwillnj

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Re: 7.9x33 question
« Reply #3 on: February 04, 2013, 10:33:56 am »
Rolling Stone

Just looking at the drawing, it looks like you might have to open up a 45 ACP shell plate a bit.   The case opening on 45 ACP shell plates I have measured run .400" to .405"

A 5/8" powder slide with a .476" hole will drop a 23 grain charge of IMR 4198.  Actually getting that powder into the case might be a different issue.  I'm not familiar with the flow characteristics of IMR 4198.  With a powder like H335 and the appropriate powder spout it wouldn't be a problem.

Based on your drawing, the length of the loaded round is less than a .223 round, and the measurement to the top of the shoulder is shorter than a 30 carbine case, so you should be able to cycle it through a Star.   A number of us load .223 on a Star.  With pickup brass, I always size it in a single station press first.  You don't have as much leverage with a Star as you do with a typical single station press.   If you don't have to do a lot of sizing, you might be able to do it in the Star, but you would need to lube the cases.

I do have some Star, and some Phelps tool heads drilled and tapped for 7/8-14 dies.

Bruce
« Last Edit: February 04, 2013, 03:02:37 pm by rbwillnj »
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Rolling Stone

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Re: 7.9x33 question
« Reply #4 on: February 05, 2013, 09:10:51 pm »
Thanks Bruce,
I've got several things on my plate right now. I haven't tried this with a .45 plate yet. I just hate to tear down a very slick machine to change it over. Do you know if the big dies will clear the casting or does it have to be butchered? The brass I have to do right now is all new and running it through a single stage won't be a problem. The powder nozzle for a .38 should be perfect as the neck is close to a .38. .354-357 OD. I haven't measured the spout yet either. I'm still in a planning mode. Look for me a bit of a dog (head) that will work on a Univ. machine. cheaper is better right now. email ujhale at gmail dot com

rbwillnj

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Re: 7.9x33 question
« Reply #5 on: February 05, 2013, 11:57:16 pm »
I'm not sure what you mean by clear the casting?   As I recall, when you use 7/8" dies, in some cases you might need to slightly modify the powder slide housing for clearance.  It's been a while since I did anything with 7/8" dies.

If you are using a Star shell plate, you will need to turn down the end of the sizing die so it can enter the recess in the shell plate.   If you use a Phelps shell plate, you "might" not have to turn down the sizing die.   

Your case will go up into the tool head when the tool head is all the way down.   You will need a custom powder spout.  Likewise you will need a custom expander.

It's not a trivial exercise...............but not impossible.............but probably not particularly cheap either.
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Kenneth L. Walters

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Re: 7.9x33 question
« Reply #6 on: February 06, 2013, 12:19:27 pm »
Have any of you ever tried to reload 7.92x33 (8mm Kurz)? The parent case for this is 30-06.

I thought that the parent case was the 8mm Mauser?
former progressive press collector

Steve Doering

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Re: 7.9x33 question
« Reply #7 on: February 06, 2013, 04:32:09 pm »
And I thought that the case head dimensions for the .30-06 and the 8mm Mauser were the same.  All I am not sure of is the diameter across the extractor groove.
S B Doering