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PostPosted: Thu Jan 03, 2019 8:53 pm 
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Does anyone know where I can find the chamber specs and the bore & groove dia. and rifling specs for the Baby Nambu? I couldn't find anything on the SAAMI site and Google search hasn't given me much either. I did find the cartridge specs in Barnes COTW (even though on pg. 326 it lists the bullet as .283" dia. and on pgs 369 & 546 it lists the dia. as .280").

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PostPosted: Thu Jan 03, 2019 9:14 pm 
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Теперь предлагаем бесплатную ежедневную маммографию!
Теперь предлагаем бесплатную ежедневную маммографию!
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This was all I found. You've actually got one???? SW

https://en.wikipedia.org/wiki/7%C3%9720mm_Nambu

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PostPosted: Thu Jan 03, 2019 11:00 pm 
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Master Sergeant
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I found other stuff on Google but not this page. This is still cartridge specs and not chamber specs. But different cartridge specs than from Barnes COTW :)!

No I don't have one (3 1/2" barrel makes it a prohib in Canada). I just wanted to compare specs for various "28-ish" handgun rounds, especially the bore and groove diameters vs the bullet diameters. The 'extra' Tokarev barrel (see my reply to your birthday greeting to me) I wanted to sleeve to take a .280 bullet and before going to all that trouble I wanted to figure reasonably good bore & groove & rifling numbers. So far I'm figuring .277 for the bore and .280 for the groove diameters for a lead .280 bullet but that is really just guesswork.

I'm looking at necking the Tokarev cartridge (or a .223 case) down from .308 to .280. This is still just for paper targets at 25 yds. Other than the barrel, using the Tokarev (or .223) case, I shouldn't need any other mods. Just shoot a couple of mags of 7.62x25, swap out the barrels and burn off a couple of mags of true 28 caliber. Just fun. No practical value at all.

NebrHogger wrote:
This was all I found. You've actually got one???? SW

https://en.wikipedia.org/wiki/7%C3%9720mm_Nambu

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PostPosted: Sun Jan 06, 2019 6:24 pm 
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I found a site that has a reamer for the Baby Nambu and they sent me an Excel spreadsheet with the drawing. (Not clear whether this is originally from some kind of "official" specs or drawn up from customer supplied cases.)

It is
Pacific Tool & Gauge

Phone:541-826-5808
Fax: 541-826-0773
675 Antelope Rd.
White City, OR 97503
http://pacifictoolandgauge.com/

They show .273 for the bore (at least I think that is what that is measuring) so maybe my guess of .277 may be too loose.

Anyway, comparing the shoulder and neck specs with the Barnes figures for the cartridge, and the rim, base, and body specs for the .223 and Tokarev chambers with the same for the cartridge specs I should be able to come to a reasonable clearance. Or, more simply, combine the base end of .223 and Tokarev chambers with the shoulder and neck specs for the .280 Nambu chamber to determine the reamer specs I'll need. :D Fun stuff! :D

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PostPosted: Thu Jan 10, 2019 9:22 pm 
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Sounds like a fun project

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