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Thread: 8mm Nambu - the cheap way!

  1. #1
    Boolit Mold
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    8mm Nambu - the cheap way!

    Recently finding myself in need of some 8mm Nambu ammo and everything I've read thus far pretty much says "Hang on THIS ain't gonna be cheap!" And searching for molds --- $200 and up, searching for dies $200 and up...well that just doesn't work for me.

    So what's a cheap bastage do? Well, here's what I did:

    First I needed a mold. I took a 30-115 (30 carbine I think) mold and opened it up to make .323" 100 gr. bullets. I did a separate post on that.

    Next I read a bunch about using 30-30 dies to swage a 40 s&w case, made sense, but the info was somewhat conflicting. In the end I went with a 32 Spl die and swaged/reformed the entire case shoulder and all. In retrospect I think I may modify this die just slightly to get the extra base diameter...maybe not I guess we'll see how they shoot with the smaller base Dia.

    Then I took a 38spl expander die and modified it to IIRC .318" At that size I machined pretty much completely thru the case hardened exterior but it will suffice for several hundred rounds until I have to worry about it. This is a learning exercise so for now that was acceptable to me.

    Next I took a 9mm seater die and tried just readjusting the seater not realizing I left a mark near the base of the case. I think I can readjust this die to prevent any case marks on my next attempts. If not I will consider modifying the die (I will search out an extra first).

    The only thing left is to figure out how I want to crimp these. The method I used was rather unconventional and I'd really like to not have to do that.

    So total cost this far? I spent 35 bucks on the bullet mold and another 10 to ship. I had the other dies laying around except I'd like to buy another 9mm seater - so I'll be on the hunt for one I can modify. I also bought a Nambu shell holder for another 12 bucks. $57 bucks so far. Leaves me quite a bit to come up with a crimp solution.

    I did have to open up the primer pockets as the swaging did affect them and I also narrowed up the rim to the original nambu rim thickness. After swaging I did ream the necks using a .312" reamer.

    Will these work? Well so far all I can tell you is that they do chamber. The rest?

    To Be Continued

    I hope this helps a fellow cheap bastage save a buck or two. If not well I hope it was entertaining just the same.

    Jacin
    Last edited by RacinJacin; 04-02-2024 at 11:35 PM.

  2. #2
    Boolit Grand Master WILCO's Avatar
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    "Everyone has a plan, until they get punched in the face!" - Mike Tyson

    "Don't let my fears become yours." - Me, talking to my children

    That look on your face, when you shift into 6th gear, but it's not there.

  3. #3
    Boolit Mold
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    Thanks for the links. I previously almost bought some brass but apparently I'm just not desperate enough to pull that trigger yet. Besides what else am I supposed to do with all this 40s&w brass I have? I don't have a 40 and i just can't bring myself to toss good brass (grin).
    I never knew the Midway story that was a most interesting read.Thanks again.


    Jacin

  4. #4
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    Wilco: That link to Firearms World looks fishy. They have "everything" in stock - (even stuff that's sold out at every place else), and at crazy low prices that are too good to believe. But, nowhere on their website do they tell you where they are located (no physical address or phone number). The third red flag is that they only accept payments in Zelle, PayPal, etc., with no options for using a credit card. The site just screams of scammer!

  5. #5
    Boolit Grand Master WILCO's Avatar
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    Quote Originally Posted by 405grain View Post
    Wilco: That link to Firearms World looks fishy. They have "everything" in stock - (even stuff that's sold out at every place else), and at crazy low prices that are too good to believe. But, nowhere on their website do they tell you where they are located (no physical address or phone number). The third red flag is that they only accept payments in Zelle, PayPal, etc., with no options for using a credit card. The site just screams of scammer!
    Thanks for the report!
    Came across it briefly and shared.
    Never dug deeper into it.
    "Everyone has a plan, until they get punched in the face!" - Mike Tyson

    "Don't let my fears become yours." - Me, talking to my children

    That look on your face, when you shift into 6th gear, but it's not there.

  6. #6
    Boolit Mold
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    In reviewing the many obstacles here there are several options for addressing rim thickness.

    1. Widen the groove
    2. Face the end of the case (not sure if the remaining case will be long enough, but this does two things, first it removes the now incorrect 40s&w headstamp - a good thing perhaps? It also necessitates addressing the primer pocket depth - I had to open up those anyways so maybe neither good nor bad.
    3. Ignore it and address it with an aftermarket extractor which you may want anyways. Not sure I like non standard parts.


    So the question is WHICH do you prefer and why?


    My first test rounds I opted for option 1. I may try option 2. just to see how it works out.

    Thoughts?


    Jacin
    Last edited by RacinJacin; 04-04-2024 at 04:00 PM.

  7. #7
    Boolit Mold
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    UPDATE: I was able to test fire a handful of rounds before it started to snow and cut my session short.

    Since I was shooting PC lead I was loading pretty light. One stove pipe and a couple trigger reset issues. Every round went into battery just fine so overall I am quite happy. Inspection of the spent cases showed nothing out of the ordinary. Still some experimenting to do, but to have successfully resized 40s&w with a 32 Win Spl die has proven interesting to say the least. The only notable observation was that the shoulder did increase a bit, but I seem to recall this happening to others even with the "right" dies. I guess I'll do a little more research there but I'm calling this a homerun so far. 200 dollar nambu dies? Keep 'em. 200 dollar bullet mold ? Keep that too. I'm gonna save that cash for more things that go BANG!

    Regards, Jacin

  8. #8
    Boolit Master


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    Hmmmmmm! Wonder what happened to the short run of Federal 8mm Nambu brass about 15 years ago and why did they stop making it. Had three range pickups at one time but have been hoodooed out of them over the years by various collector friends./beagle
    diplomacy is being able to say, "nice doggie" until you find a big rock.....

  9. #9
    Boolit Mold
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    Icing on top….well I just couldn’t leave well enough alone. Hammering the brass case from the die is ok as an experiment but kind of a drag for straight reloading. Embracing the cheap bastage deep within I still can’t pony up big bucks so….clearly we need a case ejector for the 32 win spl die. The key is gonna be simple yet easy to use. Some initial tests indicated that a simple pivot would work but the pivot is gonna need to be super close to the axis. So far it works well, time will determine if it will be durable enough. I do have concerns over the small size of thread mating my piece to the factory die. We’ll see.Click image for larger version. 

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    Last edited by RacinJacin; 04-08-2024 at 11:44 PM.

  10. #10
    Boolit Mold
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    Quote Originally Posted by beagle View Post
    Hmmmmmm! Wonder what happened to the short run of Federal 8mm Nambu brass about 15 years ago and why did they stop making it. Had three range pickups at one time but have been hoodooed out of them over the years by various collector friends./beagle
    My guess is hoarding. I guess I can't blame them when you look at prices.

  11. #11
    Boolit Mold
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    Well earlier I hinted about modifying a die to crimp with. So what I ended up with was a .41mag die that I machined a sleeve for. I put a 5/16-18 thread in the far side of the insert so that if needed it could be easily removed. Also by going 5/16 you can still use the threaded stem for seating bullets. Click image for larger version. 

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  12. #12
    Boolit Mold
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    Just in case anyone is wondering how the 32Spl die works out here's my numbers:
    .........................Book Ref.......32Spl die.........Fired case
    Neck Dia..............(.343").........(.344").......... .(.345")
    Shoulder Dia.........(.394").........(.399")...........(.40 3")
    Base Dia...............(.403")..........(.405")........ ...(.406")
    Rim Dia................(.413")..........(.408")....... ....(.408")
    Case Length..........(.844")..........(.840").......... .(.834")^
    Shoulder Length....(.604")...........(.598")..........(.650 ")^^

    ^deceptive due to shoulder change
    ^^this seems excessive but I don't believe this has anything to do with the 32 die as my number matched the book ref. pretty well. I've seen others make this observation as well. I wonder if its more the chamber/case design. I will look into this further.

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BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
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