A Friend’s Gun Exploded Today w/ RST Shell

[Craig Budgeon]

If the left most axial shaft located in the receiver is .125" dia. then the exploded cross section would appear to be between .040-.050". If that shaft is smaller the cross section would be closer to .040". Either way that's very thin that close to the breech, much to thin for my eyes!

[TxHuntermn]

Originally Posted by Craig Budgeon

If the left most axial shaft located in the receiver is .125" dia. then the exploded cross section would appear to be between .040-.050". If that shaft is smaller the cross section would be closer to .040". Either way that's very thin that close to the breech, much to thin for my eyes!

How do,we know,those dimensions??.

[Drew Hause]

I don't understand Craig.
The OPs burst is at about 9" and .040" is generally recognized as adequate wall thickness for fluid steel at that point.
The Smith Ideal chamber burst occurred where MWT at the end of the 12g chamber is usually at least .110". I did not however have the opportunity to measure that specific gun.

Another overpressure chamber blow out courtesy of David Trevallion



Likely 20g in front of 12g blow out



As said, bursts can occur with much less than total bore obstruction. A study by the Royal Military College of Science, sponsored by the Birmingham Proof House and the British Association for Shooting and Conservation, showed that an obstruction by 2 fibre wads (total weight of 4 grams) was sufficient to bulge or burst a 12 gauge barrel shooting a 28 gram (slightly less than 1 ounce) load. Peak pressure occurred 22mm (.866”) past the leading edge of the obstruction.