LOOKING AT IT A 10MM ON A 7.62X39 OR A 6.5 GRENDAL WHEN YOU NECK IT UP IT GROWES A LITTLE LEAVE IT LONG FOR 10MM BY 40MM BUT i THINK I WOULD CALL IT 40X40 JUST FOR MEAN AND CRANKY.


WHAT DO YOU GUYS THINK?

I would call it the 4x.4 or 4x4 for short. 4cm X .4" cal lol mixing metric case length and imperial for caliber.
Anything being hit by a 4x4 would know it.
Reminds me of the 400 Surtr idea but that is .410" bullets

I have a cz 527 I think I might do a switch bbl in 6.5 grendal and 4x4

How about a 4x4, 35 Gremln, 30 majoor (308 grendel) and 6.5 on a switch barrel
That would be good even steps instead of a big jump.
I know where you can get some longer 7.62x39 cases to make your 10mm fill up that 2.25" magazine. Might need to call it the 4x44 or 40x45 though.

I figured to use grendal cases for all of them it will get a little longer when it is blown out . the steps up are great but I only really need some distance on deer and a good thump on pigs up close.

That is a lot of necking up. Let us know how that goes.
I think fireball 168 came accross some cylindrical brass.