08 September 2007, 10:51
IndlovuExperieces with Gun Blow-Ups and other catastrophic events
This phenomenon was first described in artillery; has been extensively researched by many, including PO Ackley; it is not just slow powder, but a low density of slow powder that causes "detonation". several theories have been advanced as to cause, including the ones mentioned above, but I doubt if any has been proven. But the phenomenon does occur.
quote:
Originally posted by Idaho Sharpshooter:
RGB,
interesting hypothesis. Back in 1978-79 a gentleman named Caldwell (you would have liked him RGB, he had both eight bore and four bore DR's both by H&H. He even let me shoot them in the Speer test lab in the basement. You haven't lived until you have accidentally "doubled" an eight bore, even with BP loads!!) tried to replicate the SEE phenomenon. Their only success was with about a 50% loading density of 4831 in a 25-06 with a heavy bullet. Their findings pointed at a low density charge that caused the primer flame to "...dance across the horizontal powder column, igniting ONLY the surface portion...causing a back lash-type of secondary ignition of the other half of the charge...the bullet had moved forward into the chamber leade area and stopped...then got hit with the SEE of the other half of the powder charge as it ignited". They suspected that the initial flame racing across the top of the powder column may have somehow "scorched" the outside of the sticks of 4831 and burned off some of the deterrent coating. That would change the burn rate considerably, and that would cause a tremendous pressure spike at the base of the bullet. Made sense to me.
Any here with a chemical background to add to this?
Rich
DRSS
08 September 2007, 20:14
RobgunbuilderThis gets more and more intersting. Of course, everyone is well aware of the .38 special blow-up theory in that when 2.8 grs of Bullesye lies loosely scattered in a .38 special shell that a SEE can occur by a surface ignition effect followed by a secondary ignition of the powder and blows up the gun. This apparantly occurs rarely but has been documented. I seem to remember an article in American rifleman on the topic a few years back.
In the .50BMG world, Skip Talbot used to strongly advise us never to load slow powders like VV 20N29 to load densities below 180 grs as a secondary "concussion" could occur. Apparantly this happened to him at some point.
The .50BMG primers are much stronger than std primers and the case has a larger hole to help avoid this problem. Lynnn MCMurdo has shortened the case and moved the shoulder back on his varient of the .50BMG to obtain 100% load densities. I still think this is a good idea.
When we were developing the .600OK we seriously
considered designing the case for the .50BMG primers. I have a few here that I made or altered for these primers just to be on the safe side. In the end, we found we didn't need them but I can assure you it worried me alot.-Rob