The shooter who had the unfortunate experience with the "splitting" air cylinder is a close friend of mine. He is not a beginner with little knowledge of correctly charging air cylinders, but a veteran shooter who just fancied a lighter HW100.
I am sure we can all imagine what it must feel like to have that amount of pressure suddenly vent to atmosphere while holding it in your hand for a charge. In addition to an underpants change, he suffered numbing of his fingers and in my opinion was very lucky not to lose them. At least it split cleanly. I also hate to think of the outcome should the cylinder have turned into shrapnel rather than the clean split. I couldn't believe it when shown the offending cylinder.
Hopefully this item was a rogue. There again, it might not be.
Personally, this will mean, for me anyway, that I will be keeping with the original manufacturers specification for a guns air cylinder. Steel might be heavy, but I haven't heard of one suffering catastrophic damage like this one. I can remember talking to Shaun at I.S.P about the amount of pressure one of his titanium air cylinders was able to withstand, 400 bar plus on testing and still retaining integrity. Obviously then, a correctly manufactured titanium cylinder has the ability to take our normal 200 bar ish pressures without turning into a bomb.
I think that the problem has everything to do with the manufacturing process, obviously. I am not a structural engineer, but from this point I would be very careful about purchasing any none standard pressure vessel. This is unfortunate for those companies who do manufacture high quality and trustworthy cylinders, but, for me, I would never now take any risk.

Finally, this is a serious reminder to all of us who may have become blase about the continual use of highly pressurised air. We all know that our air filling and pressure vessels need to be treated with care and that the slow filling of cylinders is best practice.

Andy