Balloon Head Cases

[125JHP]

Recently while processing some R-P 45 AutoRim I noticed some of the cases have a distinct raised 'bump' in the center of the case around the flash hole. This bump looks to be almost 1/16" or so. Under the microscope, one can also detect a faint line around the case wall where the brass appears to have a seam or fold. Although on the outside they look identical to the solid head brass I have, I believe these are much older balloon head cases. They don't look quite as pronounced as other caliber balloon heads I have, but the general internal configuration looks very similar. Or could these be some other manufacturing style?

Can someone more familiar with balloon heads confirm my assumption? If they are old balloon heads, then (assuming the brass in good shape and not over-hardened), when loading these...

1. With regards to handling pressures, how do they compare with modern solid head cases? My thoughts are that they should be fine for normal 45 loads (and they will be marked for such use).

2. If they happen to get mixed in when developing a load (say for example, a heavy 260gr mammoth killer or even a 230gr JHP +P rabid mouse stopper) are there known limits compared to solid head or acp brass to keep in mind? My thoughts are that they are probably not as strong as modern brass therefore should not be used for anything above normal 45 pressures.

...or am I wrong and they will handle just about anything reasonable I can stuff in there?

[Bruce51]

This might be helpful. Some good info on AR cases from an old thread.

Bruce


Balloon head case data and stupidity

[125JHP]

Thanks for that link, interesting reading.
I looked in my Speer #6 and found some comparative data that suggests the balloon cases will either hold a 3 gr higher charge or deliver lower velocity with the same charge as solid heads, so there is a significant difference to take into consideration. However it also seems to suggest that the folded cases will handle the pressure put to them with the usual caveats about cartridge working pressure and other advisable signs etc. I think I will make a point of keeping them separated.

Collector, the top pic is a solid head and the bottom one is the one I question... its hard to tell at my magnification but it does look a lot like the one on the left shown in the referenced thread pic. Mine are R-P.

Are you saying your balloon heads don't look like that ? hmmm what are they then - some intermediate design ?

[125JHP]

OK I think I answered my own question, looking on page 430 of Speer #11 they have a comparison photo and the ones I have look like the one on the right - described as the new solid head case. So there was a transitional type as it is domed in the center where my newer cases are flat across the entire case web.

[Jellybean]

From your picture, it looks like a "semi-balloon" headed case.

[elfego baca]

I have used 45 Colt 'ballon' headed cases for maximum charged black powder loads for cowboy shoots without any problems.

[alwslate]

I have some Rem .45 AR cases of all three types and the cases in
question are not balloon head cases. I assumed the difference in
appearance was just due to them being made on different machinery
as they are not any older than the others and I don't seperate them.

[125JHP]

Thanks alwslate