I’m looking for information on brass wall thickness on the following brass. 

30/30 
32 special 
25/35 

I’m forming some 219 zipper imp brass. I’m currently using 30/30 Winchester brass. But the wall thickness seems to be the problem due to the reloading book states I’m well bellow the recommended  neck diameter causing it to have lot of soot on the neck. I’m looking for some thicker wall brass to solve my problems and hopefully tighten the groups up. 

Thanks.

Yes, I'd use pin gauges inside the neck, and then a micrometer for outside. Then just take the difference and divide by half to get an accurate wall thickness.

How did you get the neck diameter below recommended? Is your die taking it down that much?

The wall thickness on my new unfired Hornady 25-35 brass is 0.010 and I hope that is helpful. I also checked more than just one case and it's all real consistent around the entire diameter. The neck diameter on my chambering reamer is also 2825 if that might also be of some help.

If you feel the sizing die is reforming the 219 neck down a bit to much and the bullets are a bit harder than normal to seat. You can also easily make a new button to up size the necks a bit. Threads on the button are typically 8-32. Use your existing button of which already allows for the spring back to guage how much larger in size you might want to go up if that approach might be able to work for you.

Thanks for the reply and thoughts and questions. 

Wildcatting certainly my favorite thing to do.

My neck with the bullet seated is .249” OD with a micrometer. 

PO Ackley book states .2535” neck for 219 Zipper improved. 

As far as my loads. Even hot and mild loads there still spot around the neck.   

I don’t have a tube mic. That’s why I asked if anyone knew the brass wall thickness that’s been down the same path before. 

I have dedicated forming dies for my cartridge. I don’t anneal them since I don’t have much to fire form. 

With all this that’s why I was suspecting my neck is little too small. 

GR Douglas chambered and barreled the rifle. I’m sure it can’t be a chamber problem although I never did a cast. I should pin gauge the neck in the chamber see what the ID is. I don’t have a set at the moment tho. 

Thanks! 

From 4d Reamers, their neck diameter is 0.250 for a Wasp.  0.250-0.224 for the bullets is 0.0260.  That divided by 2 is 0.0130.  The average thickness of most of the brass is somewhere around 0.010 which leaves 0.003 clearance.  That would seem ideal for most rifles unless you wanted a tight neck.  Not knowing what rifle you have and what loads you are shooting, my first thought is to change powders or up the charge to get a tad more pressure.  What does the fired brass measure over the neck?  It will spring back slightly from the chamber dimension and it would be interesting to see how it differs from the 0.250 that a 4d Reamer would give.  Tom

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I was asleep at the switch and was thinking you had a 219 Donaldson Wasp.  The reamer for a 219 Zipper and the Zipper Improved show 0.253.  I would guess that the original zipper had a loose chamber for use in the lever action rifles and the zipper improved needed to stay at the same diameter so as to not need to set the barrel back.  I had some 219 Zipper brass but gave it away to somebody here when I decommissioned my 219 Improved and made it into a 30/40 Krag.   Just for the giggles measure a fired brass and let us know what it is.  Tom