6"/47 shell

I found this shell at a Scrap yard im completely unfamiliar with it. any info would be helpful, and if there is anyone that would like to add it to their collection feel free to contact me


New users can only post one picso herer is the entire thing. the crimping seems intentional, but the 4 evenly spaced holes seems like something added ???


Welcome to the Forum.

Below is some basic information on the 6 inch Mk 4 case-



it’s hard to tell from the Picture, but the 4 in Mark 4 is X ed over with a stamp and a 6 added ,

Yes, you correct.

It appears you have what started out as a Mk 4 case that was modified in some manor to a Mk 6 case. Unfortunately I cannot find the specifications for the Mk 6 case.
Also note that the case you have is shorter than the Mk 4 case and I am not sure what the purpose is for the corrugated case mouth. So the mystery continues for the moment.


The manufacturer is Norris Stamping and Mfg. Co., Los Angeles, California.

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Robert Hawkinson’s exceptionally useful Big Bore Ammunition book lists both the 6"/47 Mark 4 and Mark 6 as 152 x 972mm dimensions. However, he notes that the Mark uses a 27mm primer and the Mark 6 uses a 30mm primer. It would have been easy to modify the Mark 4 cases for the larger primer which was apparently done in this case.
He also lists 6"/47 cases 517, 636 and 700 mm long, but not designated as Mark 4.

well it is 636 and has the 4 Xed out and a 6 added So I’m guessing it is an odd ball M 6

anyone interested in adding it to their collection???