400 Cor- Bon reloading

[Don45]

I have been reloading for the 400 Cor-Bon cartridge for a while now using just lead bullets, I had tried to load some copper plated bullets but the dummy rounds I made were getting pushed back into the cartridge no matter how heavy of a crimp I put on them.

I realized that I needed to put a cannelure on these bullets for the cartridge to bite into and until just recently I didn’t have one. Now that I do have a cannelure tool I was able to do a few bullets to try.

So I made some dummy rounds using some converted 45 ACP brass and tried cycling them through the gun to see if there would be any setback of the bullet, on the five that I made I had 2 that didn’t move and 3 that did 2 of them moved 0.004.5” and 1 that moved 0.005.5”. This isn’t very much movement of the bullet so I am guessing that there should not be much change in the pressure. If anyone knows otherwise please let me know. The brass used varied in length so I am putting the movement of the 3 bullets to the different cartridge length.

I am thinking that if I make sure that all brass is trimmed to the same length and that the cannelure is placed so that the cartridge mouth is crimped into it so that it is up against the top edge of the cannelure I should hopefully stop any setback of the bullet and avoid any pressure changes round to round.

If any of you more experienced reloaders/handloaders see anything wrong with my thoughts or have any helpful suggestions I would appreciate them.

 

[colinjw]

I used to have a 400 CorBon and reloaded for it.
I used Starline 400 CorBon brass & also converted some 45ACP's for low velocity rounds.
I did not have a problem with the bullets getting pushed back into the case with
either lead or jacketed heads.I also did not need a canellure or a heavy crimp.
i would suggest that you might be opening the case neck a little bit too much
and therefore not having enough friction to hold the head firmly in place after you seat it.

 

[Don45]

I will double check the opening of the case mouth but I doubt that it is the problem as I usually set the case flair to open up the case mouth just enough to allow a bullet to enter the case mouth without shaving off any lead when using lead bullets.
I also have some Starline brass but was using the converted 45 ACP brass for the dummy rounds.
Thanks for the suggestions.

 

[Beater]

I shoot 400 aswell, and have never had those problems. it makes me wonder if you are having troubles with the feedramp and or maybe catching the mag lip or something weird like that

 

[ted_dent]

I will double check the opening of the case mouth but I doubt that it is the problem as I usually set the case flair to open up the case mouth just enough to allow a bullet to enter the case mouth without shaving off any lead when using lead bullets.
I also have some Starline brass but was using the converted 45 ACP brass for the dummy rounds.
Thanks for the suggestions.

Remember that plated/jacket bullets will probably be .001" smaller in diameter than the equivalent lead bullet so will need less case mouth flare (yes, that's the proper term) than lead. Like the .357 Sig the 400 Cor-Bon has a very short neck so getting sufficient tension on the bullet is not easy so one thou can make a difference. I haven't reloaded 400 Cor-Bon for a while but seem to recall in my initial reading that light bullets should be used (165 gr. and under). While I'm not a physicist that makes some sense regarding bullet setback as I would expect heavy bullets to have more inertia on recoil than light bullets (just as heavier bullets are easier to pull with an inertia bullet puller than light ones). While a cannelure is desirable I haven't found it necessary. Mind you my loads were fairly mild (7.5 gr. of Unique over a roll crimped 155 gr. HBFP Berry's bullet) but I experienced no setback and excellent accuracy out of my Glock 21.

 

[Don45]

Thanks for the tips guys, I was trying to use some 180 gr. bullets I have for my 40 S&W so that is likely most or at least part of my problem. Now to find some that are 165 gr. or under.

 

[Garand]

I'm using .45 Super cases sized down to .400 CorBon at the moment. I've got 500 virgin .400 CorBon cases that I haven't tried yet and I'm using 165 grain CMJ bullets. My problem is that my .400 Cor Bon barrel needs throating and polishing.