338 300 RUM forming question

abinok

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Nov 25, 2004
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I'm thinking about giving this wildcat thing a try for my next barrel. My current setup is a Savage 112 bvss in 300 WM. I'm running the 220 SMK at just over 2700, but its out if steam by 1200-1400 yds depending on temp. Living on a ranch here in OK, I've got 1800 and change to shoot across, and it seems a shame to not be ale to use it all. I know there are a few different kinds of 338/300 RUM wildcats floating around out there, so I was hoping for some advice. So here's what im thinking. Run a 338RUM Ackley reamer in deep to use the longer case (I know a few others are already doing this) but instead of using the 300 case, why not use the 375 RUM case. I was thinking that using this case instead, would leave enough of the 375 diameter neck unsized to act as a false shoulder to control headspace during fireforming… kind of like running a 30-06 case into a 280 rem die. All you would need as far as forming dies would be a 338 RUM fl sizing die. Would this work? The only wildcat/ caseforming ive done is the 06 to 280 and 7mm Rem mag to 30-338. Am I oversimplifying this process, or have I completely lost my mind? HELP!!
 
I believe the 338 RUM case is the only one that was designed shorter, so necking down the 375 should work just as you plan.

You also avoid creating a doughnut up in the newly formed necks, and also creating thin spots in the necks by using 375 RUM brass verses expanding the 300 RUM to make them work.... both pluses in my mind.
 
Thats what Iwas hoping... but with so many things, especially wildcats, theres nothing new under the sun. I had figured that if it was a good idea somebody would have already done it.... and if its a bad one somebody could set me straight.
Im just glad to hear I might be onto something /ubbthreads/images/graemlins/grin.gif
 
That'll work. My version is called the 338 Mystic. I use 300RUM brass simply because that is what I have on hand. I am throating my chamber (separate step) to handle the 300grMK seated way out. The necked down 375 case will save one extra step.

Look up 338 Tomahawk. Some good data on that too.

Jerry
 
Hey Jerry,
I was looking through my midway usa cataloge yesterday and notticed they had the throat cutting tools... but no 338. Any tips on where to find mine?
now I guess I gotta pick a name... maybe 338 clavicle cracker.... or 338 BB (bakers big)gun /ubbthreads/images/graemlins/grin.gif
 
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