Jack et al:
Just to clarify the matter of cartridge case heads and their proper nomenclature, let's go back to the beginning. (Just for the record, I didn't read all of the earlier posts, so someone may have covered this. *If so, I apologize.)
A true balloon head case, also known as a folded head, was made entirely of thin metal and most resembled the current rimfires. *Some had a primer pocket bumped in and some had internal primers and actually look like rimfires. *These were the type which gave so much extraction difficulty in the Trapdoor Springfields in their early years.
Solid head (early type)(aka semi-balloon head):
This is the type which is now usually referred to as "Balloon head", and sometimes, even now, as a "Semi-balloon head" but really isn't either. This is the type Keith referred to as a Semi-balloon head because he was old enough to be exposed to the real Balloon head. Keith lived at a time in his earlier life when any of the three types could be encountered. *This, as Jack said, has a base only as thick as the rim with a protruding primer pocket. *Some early examples of this type had the letters S H included in the headstamp to differentiate them from true (considered, and actually, inferior) Balloon head cases. *Most of these cases do date back to the 30's with some Dominion .450 and .455 being much later, since this case is so short it was the only way to get any capacity.
What we can probably refer to as a "True Solid Head", cases as we know them now.
Going back to the early type solid head. *There are several problems with them which should put them out of the running for loading:
1) As Jack said, the head is only as thick as the rim which places the area of stretch and ultimate failure outside of the chamber. *When modern solid head cases fail (head separation) it occurs inside the chamber and usually causes no mischeif, even in a high-intensity rifle cartridge since the failure occurs in a place whenr there is a portion of the body still on the head which acts as a gas check. *Just for the record, this "gas check" is properly known as an "obturator".
2) There is a sharp corner at the case body/rim junction which is a stress riser. *If you have an old loaded cartridge and want to know if it is an old or modern type solid head, chech at the front of the rim. *Modern cases have an undercut in front of the rim and the old style have a sharp corner. *This sharp corner is probably the real cause for this type of case not being made since that sharp inside corner is formed by a sharp and delicate portion of the forming dies which would have a relatively short life as a result.
3) Most old style solid head cases date to the time of Mercuric primers, even if the charge was smokeless. *Mercury, even in very small quantities, forms an amalgam with many metals causing them to lose their ductility and resulting in embrittlement. *This, and #2 combine to abrogate theproblems already caused by reason #1.
As a result of the listed reasons, the old style, now usually referred to as balloon head, have a very short life, frequently only 2-3 loadings. *The only possible reason to use such brass is with black powder since they have much greater capacity than modern cases. *Even with black their life is short and when they do fail (I had one lose a head in a .44-40 with 40 gr. FFFg, even with solid ear plugs the result was about the same as firing a gun in a small room without hearing protection! This was in a replica '73 Win. carbine, thank goodness for safety glasses.) the effect is less than interesting.
In short (Too late!
, don't use them for any reason, even brass which appears to be un-fired. *They do fail and it can be very serious. *Modern powders do not require nearly the capacity which most revolver/carbine class cartridges already have.[B]