284 Colton Magnum

joenurse · December 15, 2009, 04:34 PM

I have just purchased a rifle in this old wildcat and am hoping that someone has some info about it. It is a 338 Win Mag necked to 7mm with the shoulder widened to increase case volume.

Any info on ballistics, reloading data, or the development of the cartridge will be appreciated

Thanks

GeauxTide · December 15, 2009, 08:26 PM

If it's a 2.5" Mag case, then I'd start with the 7mmRM data as it is pretty conservative. My first 7mm was a Weatherby, which is tapered very little in the body and has a longer neck. With 4831, I'd reach max about 4 grains after the 7mmRM with identical bullets, mainly because of the 3/4" freebore that was employed in the MarkV rifle. I've had sucess with 154-162gr bullets in the 7mmRM using IMR 7828. If you have a standard throat, I'd start with 63gr of IMR7828 under CCI250s with 154 Hornady's and see what you get. Hornady 7 says 65 is max.

December 15, 2009, 04:34 PM	#1
joenurse Junior Member Join Date: December 15, 2009 Posts: 1	284 Colton Magnum I have just purchased a rifle in this old wildcat and am hoping that someone has some info about it. It is a 338 Win Mag necked to 7mm with the shoulder widened to increase case volume. Any info on ballistics, reloading data, or the development of the cartridge will be appreciated Thanks

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December 15, 2009, 08:26 PM	#2
GeauxTide Senior Member Join Date: April 20, 2009 Location: Helena, AL Posts: 4,423	If it's a 2.5" Mag case, then I'd start with the 7mmRM data as it is pretty conservative. My first 7mm was a Weatherby, which is tapered very little in the body and has a longer neck. With 4831, I'd reach max about 4 grains after the 7mmRM with identical bullets, mainly because of the 3/4" freebore that was employed in the MarkV rifle. I've had sucess with 154-162gr bullets in the 7mmRM using IMR 7828. If you have a standard throat, I'd start with 63gr of IMR7828 under CCI250s with 154 Hornady's and see what you get. Hornady 7 says 65 is max.