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Old 08-09-2006, 04:03   #284
English
Senior Member
 
Join Date: Dec 2005
Location: London
Posts: 5,843
Quote:
Originally posted by mobocracy
Please do detail your experience with revolver KBs not directly attributable to overcharges. I've seen KB'd revolvers, but they were always associated with double charges of fast powders.
I am not denying the existence of many KBs due to overcharging and many due to the less obvious problem of sub minimal loads flashing over. These are all well know and well understood. Equally, a slightly too large bullet with a normal charge will cause a KB - this does in fact obstruct the bore, just as I am suggesting for other cases, for long enough for the pressure from a normal charge to build high enough to burst the barrel.

When we take away the obvious cases of why KBs happen we are left with a mystery. There seem to be many cases where none of the obvious reasons apply. I am doing no more than try to address those cases.

To answer the question directly: no I have no personal experiences with revolver KBs. Neither do I know of anyone who has such experiences in any number which would provide significant evidence.

I know of one case in which a friend changed his mild revolver loads to a different but seemingly identical lead bullet from a very respected maker and changed propellant at the same time to a charge that should have had the same power. (There were complicated reasons for why he made two changes at the same time.) They were rather inaccurate but the first that he knew of a real problem came on only the second cylinder when the cases would not extract. He found massive leading and was obviously close to a KB. He is meticulous about cleaning and so he was sure that there was no leading before he started the session and I am sure he was right, but after a hard time getting the leading out he fired another six to see if it was a freak occurence. The result was more heavy leading and he stopped the experiment before the cases seized in the chambers. He scrapped all his ammo from that batch but opened and measured the charges and they were as they should have been.

This is not conclusive evidence of anything other than that we are playing a game with rare random dangers.

The position that many of us fall into is to assume that we understand these dangers and that they can't happen to us because we know better. I believe that the "knowledge" that loose Glock chambers cause KBs is one such example. No one has come up with any sensible mechanism by which a loose chamber can cause a KB. Before someone tells us again that Glock chamber walls are thinner than X chamber walls, can I repeat that they still do not burst with normal pressures and that an exceptional event is required to seize a case into a chamber or burst a barrel. Both of these categories expand the bore size before in one case it bursts and in the other it springs back to size. Other makes might offer a little more margin but the phenomenon still exists.

English
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