223 neck tension and Mr. Bullet Feeder...

[78Staff]

Setting up an MBF 233 conversion kit - have been using it with pistol with great success, but am a bit confused on the best way to set neck tension on 223.  I size/trim with an RT-1500, which tightens up the neck a bit, so use a Lyman M-die to open it back up.  I though I had read either on the MBF site or possibly on the web to use the M die to set neck tension/size to 224 - but then I was told 224 was much to large and would not keep the bullet secure in an autoloader.  However if I don't open the neck up with the expander, the bullets topple as soon as the shellplate advances (Hornady 55gr bullets, sight boattail base)

 

So what's everybody doing for neck sizing 223 when using a Mr. Bullet Feeder?

 

 

[DWFAN]

You just want the neck large enough to hold the bullet until it can be seated. So .224 at the very top will probably be fine, just dont make the full neck .224 or you wont have any neck tension. .222 or .223 would be good to try, especially for boat tail bullets.

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[78Staff]

I notice the Swage hold back rod also opens up the neck a bit as well, and with a smooth stroke the bullet seem to say in place.  Putting on hold for now though as I have a auto drive coming so will pick up again after I get it up and running.