7MM Super Mag

Have a question on the 7MM Super Mag .I have run into a E Arthur Brown single shot falling block pistol chambered in this .The question is the seller knows nothing about it and just wants to sell it(estate) ,no dies, no brass .I am guessing it is mid 80s vintage /also has a pachymar dominator for sale too 308win but no interest but figures to about the same era

So what case is it based off for the 7mm super mag ?

did more google and found it ,looks to be 357 max case or 5.6x50R and wow SHORT NECK form pics

I believe that is made from the 357 maximum case. I recall hearing it's basically a 7mm TCU but rimmed. Could be fun!

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I just recently purchased a TC Contender barrel (10”) myself in this chambering. Like you, I have uncovered very little info on this round. So I went ahead and ordered 7mm TCU does, and 200 .357 Max unfired cases.
I understand annealing is a must. As you state, it has a very short neck, so cast boolits may not work so well. Just a little more case capacity than the TCU, so I will start with that starting data. This will be my first wildcatting adventure.
Best wishes if you get it.

Contact EAB Co. directly. They can answer your questions. BTW the Pachmayr Dominator is a great quality " upper" for a 1911. A friend hunted exclusively with his in .308 for years using appropriate hand loads for squirrels to deer&hogs.

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if that is one of the pistols that was a falling block made earlier and called a BF at that time(think EAB bought the rights to make it later), they had a 7mm made from 357mag cases IIRC and it had only about a neck length of 1/8" or so. It shot well, but went down the road. Dies would be good as they probably near to impossible to find and if you do, quite $$$. You MIGHT be able to load it using cut down 7mm tcu dies and a 357mag size die for the body.
Otherwise, its a desk paperweight.

Years ago when Sillywett was more popular, one of my friends competed with a 7mmSM in a Contender. It is based on the .357 Max. and has a very short neck. He did well with it and didn't have too many issues forming and reloading cases. I used and still shoot a .270 Super Mag in a BF format and find it a great cartridge and fantastic pistol. It does very well with cast and has a slightly longer neck than the 7mm. EABCO used to have data for the cartridges and I use XMR 2015 exclusively in it with 150 gr. cast or condom boolits.

Attachment 257434

Ok I did end up with both the EA Brown and the dominator ,turns out the dominator has a lower frame (colt ).Will have to wait for the transfers and go pick them up .The price was the same weather I took the Brown with or with out the dominator ,So a friend wants the 308 so it is a win for both of us .As for the dies will cross that bridge when I get there or change out the barrel to something to something more common ..I really wanted it as it is a nice compact falling block

transfers complete and home now
So the brown would not stay open and kept popping shut .WHAT a hateful lil bugger to take apart for cleaning and that lil screw for the extractor with red locktite ,now chamber cast and cleaned up .
Was thinking of lengthen the neck to at least the diameter of the bullet and using 5.6x50 brass and it shouldn't affect the use of the short neck
Made up some test rounds on 357Max brass and fire formed them ,still not a fan of the neck.But still pondering before locating dies

here is a pic of the pair
Attachment 257946
Attachment 257947

Went with a plan B .Recut the neck to .250 and switched the brass to 5.6x50R to use the longer neck so basically a 7TCU rimmed now Attachment 258028

How did you lengthen the neck?
7mm TCU reamer?

used a 7mm necking reamer .315 ,made up a pilot bore to fit the chamber and bored a hole to fit the reamer shank to hold all true.Took about an hour and a half to make the pilot and set up and 3 minutes to cut it ...LOL

What's up with the .308 Dominator barrel? The muzzle end looks like its had a torch to it?

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LOL ,no flame just light and oil smudging .Does kind of look that way