The 401 Mags contained a 200gr LRN bullet and 11.0grs of powder. Being that the ammo was made in Sweden, I wouldn't guess what the powder was.

oldman10mm, post or send me a good picture of the powder...I'll compare it to my files to see...

401 Mag powder on the left in SS tray, SR4756 on the right in plastic cap.
Larger 'kernel' than SR4756. The 11.0gr load I found in them corresponds exactly with my 10mm 'top end' loads of SR4756 with 155gr bullet.
Now their bullet is heavier at 200gr (weighed) so it should be a slower powder than SR4756.

Australian Powder AD70N comes to mind



I have some load data for this powder but not for the 401 Power Mag.  Data for the 41 Mag shows less powder than what you measured with 200 grain bullets.

Rcc brass in Texas will manufacture rimmed 10mm and rimmed 10mm mag. Found them while looking for 401 powermag brass.
Kinda pricey talked to Jeff the owner and he will do small batches of anything you want.

Looked at RCC Brass, interesting site. $3 - $5 (each) typical price for custom brass. The box of Herters 401 Mag ammo I picked up at the Akron show was $40 for the box of 50. He only wanted $40 as for as long as he has had it, he never had anybody ask for it. He was glad to get rid of it.

He uses a proprietary machining process rather than the typical draw process so they will supposedly hold up longer.
Like I said though they are pricey. He is also 90 day lead time.

Did my full write-up here

http://smith-wessonforum.com/s-w-revolvers-1980-present/647533-making-10mm-rimmed-brass-use-610-a.html#post141118897