7m/m Gradle Express Rimmed


#1


Some time back I acquired a Wilbur Hauck single shot rifle in what was marked simply 7/mm. It was obviously not a 7x57. After a chamber casting it revealed itself to be chambered for the Roy Gradle 7mm Express Rimmed. There is a rimless version and thankfully this is not it as I do not relish the idea of turning rims and turning in extractor grooves in the brass. A set of dies was obtained (believe it or not they were in inventory at Redding). The first fire-formed cases have been made. The case is pictured next to a 7mm WSM. This is a fire-formed only case. This rifle was built in 1961. The ‘Short Mag’ was around long before Winchester “invented” it. This is the third version of this case as I had encountered in researching loading data and history of Roy Gradle, the rimless version with a radiused shoulder that transitioned abruptly to the neck and this double radius ala Weatherby type neck. And true to form as a ‘wildcat’ the shoulder is .060"/1.52mm longer in this particular chamber than the others.
Case dimensions;
case length; 56.28mm
base to shoulder; 44mm
base to neck; 48mm
dia @ shoulder; 13.27mm
base dia; 13.86mm
neck dia; 7.92mm
Roy Gradle retired in 1965 and died in 1976 in Santa Barbara, CA. Gradle was a friend of both Roy Weatherby and Wilbur Hauck. Wilbur sold his single shot actions in the white to other gunsmiths. These were unnumbered as is this one. However, the barrel is marked Wilbur Hauck Arlington, VT. I suspect he sent the action to Roy for chambering and for some reason never numbered it. The limiting factor in equaling or exceeding the 7WSM or 7Rem Mag is the brass is not as heavy and pressures will be limited by that.
Thought the wildcat fans might like to see the current project.
David


.348 Winchester Wildcat?
#2

Thanks Steve, we’ll see the ballistical data


#3

The fire-form load produced a nominal 2640 fps. with a 140 gr bullet and a slow IMR powder. A certain amount of energy was used forming the case but producing enough pressure to fully form the case. This week I will place a strain gage on the chamber and start load testing with it hooked up to an RSI pressure trace system.
Quickload and Load from a Disk both show theoretical loads with 140 gr bullets maxing out at 3100-3200fps. Essentially it is what the current 7mm magnums are.