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4/22/2019 5:32:20 PM
Posted: 4/22/2015 9:12:29 PM EDT
I'm reloading some Nambu 8mm necked cases using CH4D dies and 100gr FMJ bullets. I've belled the neck mouth enough to accept the bullet, but when I seat the bullet, it partially collapses the neck on one side to the point where the loaded cartridge won't fully chamber. What is the trick with reloading thin necked pistol cartridges like the Nambu 8mm and .30 Mauser?
Link Posted: 4/22/2015 9:26:45 PM EDT
Link Posted: 4/22/2015 9:29:33 PM EDT
Seat and crimp in separate operations.
Link Posted: 4/22/2015 9:30:26 PM EDT
That's exactly what my FMJ bullets look like. I've not had issues with any straight walled pistol ammo I've reloaded (like you've pictured), but these little necked Nambu 8mm cases are very thin and when I seat the bullet, it partially collapses the neck.
Link Posted: 4/22/2015 9:31:55 PM EDT
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Originally Posted By 243winxb:
Seat and crimp in separate operations.
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I'm not crimping (and this seating die doesn't appear to have a taper crimp feature.. I'll try raising the die body so that the case isn't fully seated in the die.
Link Posted: 4/22/2015 10:46:19 PM EDT
I have has to lube the inside of the case mouth on a few similar calibers before. It might be worth a shot of you apply a light crimp afterwards.

I have also found that the brand of brass makes a big difference, but you don't have many options in 8mm Nambu beyond forming from 6.8 SPC.
Link Posted: 4/22/2015 11:07:08 PM EDT
[Last Edit: 4/22/2015 11:18:01 PM EDT by cantgrowup]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Ridgeline:
I have has to lube the inside of the case mouth on a few similar calibers before. It might be worth a shot of you apply a light crimp afterwards.

I have also found that the brand of brass makes a big difference, but you don't have many options in 8mm Nambu beyond forming from 6.8 SPC.
View Quote


Yes... I am using Huntington's 8mm Nambu cases. I will try putting a little Imperial Wax on the inside of the necks before seating. I'll have to explore my options for crimping this particular cartridge. Like I mentioned... my CH4D seating die doesn't appear to have a crimp feature. I've just written CH4D to see if my dies have a roll crimp feature
Link Posted: 4/23/2015 11:13:45 AM EDT
Your die is adjusted too far down and is contacting the shell case before the seater plug seats the bullet to the correct depth. Raise your die a little and reset the seating depth.
Link Posted: 4/23/2015 12:39:34 PM EDT
Link Posted: 4/25/2015 11:07:15 AM EDT
On my little bottleneck cases (25-20 and 30Mauser), I use a Lyman M die to expand the necks for cast boolits, and seating is done before crimping. In this manner mangled brass is a thing of the past.
Link Posted: 4/25/2015 1:19:29 PM EDT
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Originally Posted By sfno72:
Your die is adjusted too far down and is contacting the shell case before the seater plug seats the bullet to the correct depth. Raise your die a little and reset the seating depth.
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This is my thought also.
Link Posted: 4/29/2015 10:28:07 AM EDT
Thanks guys... I raised the seating die a bit (and also confirmed with CH4D that this 8mm die does have a crimp feature). When I raised the seating die, the collapsed neck problems were eliminated.
Link Posted: 4/29/2015 2:00:41 PM EDT
Link Posted: 5/3/2015 12:05:24 PM EDT
What brass are you using? I am workng on a friends Nambu and am trying to source either loaded ammo or brass cases. In my Nambu thread in gd, a poster mentioned forming 357 sig brass.
Link Posted: 5/3/2015 2:51:52 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By sfno72:
Your die is adjusted too far down and is contacting the shell case before the seater plug seats the bullet to the correct depth. Raise your die a little and reset the seating depth.
View Quote


This was my first thoughts as well

Good luck you'll figure it out
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