Herter Powermag conversion


February 22, 2004, 01:59 PM

I have a 1960's vintage Herter's Powermag revolver in .401 Magnum that I would like to convert to .41 Magnum. Does anyone know if such a change is feasibile? If so, any ideas on how much a gunsmith might charge?

Thanks for any help.

If you enjoyed reading about "Herter Powermag conversion" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
February 22, 2004, 04:19 PM
The existing cylinder can be rechambered easily enough, though the cost is another factor.

Your barrel would need to be replaced. It is too close to .41 to rebore. Cutting a new barrel from a blank would entail a fair amount of work. It woyld have to be turned to the correct diameter, threaded, the throat would have to be cut, a front sight mounted, the stud (or hole) for the ejector rod housing screw would need to be located and machined, the muzzle crowned, the barrel fitted. Can you see where all this is headed?

Caliber changes on Colt or Ruger single actions are not as expensive, as there are existing barrels and/or cylinders to be had, but even then it isn't cheap.

Brass is available, as are loaded cartridges. I have heard that you can buy (or perhaps modify) dies to swage .41 Magnum brass down to .401 Powermag. It is actually a pretty cool cartridge in its own right.

February 22, 2004, 07:00 PM
Can you see where all this is headed?

Yes indeedy! Mucho dinero.

Thanks for the reality check, Otony. Really I don't have anything against the .401, other than the fact that newly manufactured ammo is pretty pricey. I also got "sticker shock" when I saw prices for case forming dies, so reloading is not an option for me.

I am really fond of the old Herters revolver and think it would be all the deer-hunting handgun I'd ever need.

February 22, 2004, 08:01 PM
I have heard of a few fellows grinding off the bottom of a .401 sizing die (so as to get to the very bottom of the brass), and squeezing/swaging .41 magnum brass.

This wouldn't be too bad to try, if only .401 dies were a bit more common, eh?

I almost had a .401 built up on a Ruger Blackhawk once upon a time. It was a limited edition, that had 10mm and .38-40 cylinders. Figured a .401 would just finish the set!

February 23, 2004, 11:50 AM
Why not just rechamber it to 10mm?

February 23, 2004, 12:07 PM
The .401, even though it takes a 10mm BULLET, has a case larger in diameter than the 10mm auto. The .401 case is also longer, by .30". No way to rechamber, there is too much steel missing already.

Jim March
February 23, 2004, 01:13 PM
Then the solution here is to get a 357 or smaller cylinder and have that fitted and bored up to your choice of 40S&W, 10mm, 10mmMagnum or 38-40.

If you have access to a gunsmith's "box of old cylinders", you can test-fit the smaller-caliber cylinder by putting it in and doing the "timing with a flashlight" check - make sure each cylinder bore lines up with the barrel. You'll need to shine light in down the muzzle end and peer over it but it should be doable. That plus checking endshake and making sure rotational play is OK will get you a cylinder that just needs reaming out to the bigger caliber. This won't screw up your Powermag cylinder at all.

February 23, 2004, 01:31 PM
I am sorry if I was unclear. I meant rechamber a new cylinder. Keep the original so the gun still has it's somewhat limited collectors value.

I believe they were made by Hawes and I think Numrich has cylinders available. The Hawes guns were made under several names.

February 23, 2004, 02:25 PM

I'd also like the 10mm conversion if only it didn't sound so expensive.

While we're discussing possible conversions of the .401 Powermag that are also less costly, how about a conversion to .38-40? I realize this old cartridge is pretty much underpowered, but it's very shootable. (At least from what little experience I've had with it. ) If you had cylinders for both the .401 and the .38-40, it seems you could have the best of both worlds. (Maybe?)


February 23, 2004, 02:44 PM
Ah, now we are on to something. BluesBear, Jim M., you have a very good idea. Yes, there are cylinders available from Numrich/Gun Parts, a friend found his 9mm cylinder from them.

A 9mm (or .357) cylinder could be easily rechambered to 10mm, or .38-40 for that matter. The original .401 could go to .38-40 as well. Those cylinders are not too terribly expensive, and with some shopping around, well, it might get done under $200 all up.

Too bad the .401 died, I really like the cartridge.......

Jim March
February 23, 2004, 02:59 PM
Wait...I've been assuming this gun is a wildcat based on a Ruger Blackhawk or a Colt (or clone?). In all of these cases, smaller cylinders are floating around. In the Ruger, you could even start with 30Carbine although those are probably far less common than 357 and 9mm cylinders...

February 23, 2004, 03:05 PM
If you have a loading press, 41mag shell plate, Dillion 10mm sizing die & case trimming tool you can make .401 PowerMag rounds from .41 Rem Mag brass. This works quite well.

1. Trim brass to .401 PM length (measure factory case.)
2. Warm brass (I put it in an oven @ 170 for 10 minutes.)
3. Bottom sizing die in press with the ram raised with no shell plate
mounted. Remove center stem from die.
4. Squirt 10mm sizing die w/ Hornady's One Shot.
5. Size brass all the way into the die, lower ram, use large (as large as will
fit into the sizing die) brass rod and hammer to punch out brass.
6. Check primer pocket and flash hole for deformation (I've never had any.)
7. Load ammo w/ .41 Rem mag shellplate, 10mm sizing die, bell die and
seating die
8. 10mm bullets & call Accurate Arms for .401 PowerMag loads.
9. Champhor (sp?) cylinder charge holes SLIGHTLY w/ a dremmel.


February 23, 2004, 10:22 PM
The Herter's .401 Powermag was a single action revolver sold exclusively by Herter's in the mid to late 1960's.

My brother bought a new one around 1967. Ahhh the good old days of mail order.

It was a pretty good cartridge and the Hawes built Herters revolvers were sturdy. They had a slightly larger grip somewhat akin to a Super Blackhawk. It was accurate and powerful. Too bad it didn't catch on. I attribute that gun for starting my interest in .41 magnum.

After the GCA of 68 made getting ammo difficult my brother traded his back to Herter's for one just like it in 44 Magnum. It was a nice gun but it just wasn't as much fun to shoot as that .401.

Jim March
February 24, 2004, 01:45 AM
Ah. So it's NOT a conversion.


Wonder if the cylinder is SAA-sized or not? If available in 44Mag, prolly not.

Well dang. I'm outta answers then.

Lloyd Smale
February 24, 2004, 05:45 AM
If you want my opinion leave it alone! the 401 is a good round. save some money and stock up on brass. That gun will do nothing but go up in value. There already getting hard to find. If you really would rather have a .41 im sure you could find someone with a .41 that would trade you even up.

February 24, 2004, 08:45 AM
To be perfectly honest, converting my Herters revolver is something that will probably never get past the idea stage, but it's been fun and informative to talk about anyway. I agree that the Powermag has some potential for collectability and shouldn't be tampered with, but it would be a plus to have spare cylinders in calibers that are more shootable, such as the 10mm/.40 S&W or the traditional .38-40.
Thanks to each of you for sharing your knowledge, advice and opinions.

January 18, 2011, 01:39 PM
... I figured I'd post this link (http://gadcustomcartridges.com/) to a supplier of .401 ammo.

January 18, 2011, 06:45 PM
Thanks for that, but I sold the Herter's to a relative a few years ago. He's as happy with it as a pig in sunshine! :D
I will let him know in case he's interested. He was really happy with the two original factory boxes of mostly unfired ammo I gave him. Hated to let it go, but I needed the money!

January 18, 2011, 06:46 PM
According to John Taffin's writings, all you need to do is run .41Mag cases through a carbide 10mm sizer die and voila.

January 19, 2011, 05:55 AM
According to John Taffin's writings, all you need to do is run .41Mag cases through a carbide 10mm sizer die and voila.

Yes, a .401 Herter shooter/reloader told me that he did that very thing regularly whenever he wanted to do some cheap shooting. I guess that's why my nephew was also tickled over the once-fired .41 Mag brass I gave him.

Gee, I hope he remembers my generosity one of these days!
Like today? :D

If you enjoyed reading about "Herter Powermag conversion" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!