357 Mega

D-Ric902 · February 25, 2012, 04:23 PM

I was thinking today when reloading some 40 S&W
If a 357 sig is a necked down 40, why not neck down a 10mm?
major league velocity, easily 357 mag rifle performance with a bonded bullet

Anybody tried this?

vladan · February 25, 2012, 05:35 PM

9x25 Dillon

**Unclenick** · February 25, 2012, 06:04 PM

Yes, that's right. It's the 9×25 Dillon. It was developed in the late '80's and used by Rob Leatham for a time, among others.

AFAIK, the 9×25 Dillon has no advantage over the .357 SIG. This is because it is loaded to lower pressure (36,000 psi vs. 44,000 psi). I don't know if that was done because of the pistols they could chamber for it at the time, or if it was because the 10mm Auto case head wouldn't handle as much pressure. Perhaps it's just that the 10 mm case uses a large pistol primer rather than the .40's small pistol primer and the latter is a little more resistant to piercing and gas leakage. You'll notice that cases for the .454 Casull and other high pressure magnum pistol cartridges often are made with deeper primer pockets to use thicker cupped large rifle primers rather than large pistol primers.

markr · February 26, 2012, 01:16 PM

It's small rifle primers in .454 Casull, not large rifle.

Goldy · February 26, 2012, 03:08 PM

9X25 Dillon didn't need to be a high pressure round. It only had to push a 125 grain bullet to 1410fps to make major.

It didn't last because of magazine capacity was less than 38 Super.

Toxdoc · February 26, 2012, 05:25 PM

Quote:

If a 357 sig is a necked down 40, why not neck down a 10mm?
major league velocity, easily 357 mag rifle performance with a bonded bullet

I'm getting about 1650 fps with a 115 grain bullet with 9x25 Dillon of of a 6 inch barrel. I think I can push that up to around 1750-1800 fps. Hodgon's data suggests that out of a rifle you can get well over 2000 fps with a 125gr 357 magnum. While the 9x25 can be a barn burner out of a handgun, the rifles still win. I have toyed with what it might take build an AR in 9x25 Dillon and I'm not sure I'm ready to take that step.

D-Ric902 · February 26, 2012, 07:31 PM

Double Tap says they are getting 1700 with a 124 grn jhp.
Sounds like an awesome round if accurate.

Toxdoc · February 26, 2012, 08:07 PM

It is easy to get into:

Glock 20
Lone Wolf Conversion barrel
(not a bad idea to put in a stiffer recoil spring)

I think double tap is the only commercial loader for the round. Dillon sells dies and they aren't cheap. Finding 10mm brass is the toughest part.

**Unclenick** · February 28, 2012, 05:06 PM

Quote:

Originally Posted by markr

It's small rifle primers in .454 Casull, not large rifle.

Yep. I was thinking of the .475 Linebaugh and typed .454 Casull. Thanks for the catch.

February 25, 2012, 04:23 PM	#1
D-Ric902 Senior Member Join Date: May 29, 2004 Location: Northeastern Indiana Posts: 402	357 Mega I was thinking today when reloading some 40 S&W If a 357 sig is a necked down 40, why not neck down a 10mm? major league velocity, easily 357 mag rifle performance with a bonded bullet Anybody tried this? __________________ mercysdad.com Last edited by D-Ric902; February 25, 2012 at 04:31 PM.

February 25, 2012, 06:04 PM	#3
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,093	Yes, that's right. It's the 9×25 Dillon. It was developed in the late '80's and used by Rob Leatham for a time, among others. AFAIK, the 9×25 Dillon has no advantage over the .357 SIG. This is because it is loaded to lower pressure (36,000 psi vs. 44,000 psi). I don't know if that was done because of the pistols they could chamber for it at the time, or if it was because the 10mm Auto case head wouldn't handle as much pressure. Perhaps it's just that the 10 mm case uses a large pistol primer rather than the .40's small pistol primer and the latter is a little more resistant to piercing and gas leakage. You'll notice that cases for the .454 Casull and other high pressure magnum pistol cartridges often are made with deeper primer pockets to use thicker cupped large rifle primers rather than large pistol primers. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

February 26, 2012, 01:16 PM	#4
markr Senior Member Join Date: January 23, 2008 Location: Arsenal of Democracy Posts: 405	It's small rifle primers in .454 Casull, not large rifle. __________________ I like to make beer, bullets, and jerky.....but not at the same time. Washed up 11B1P

February 26, 2012, 07:31 PM	#7
D-Ric902 Senior Member Join Date: May 29, 2004 Location: Northeastern Indiana Posts: 402	Double Tap says they are getting 1700 with a 124 grn jhp. Sounds like an awesome round if accurate. __________________ mercysdad.com

February 25, 2012, 05:35 PM	#2
vladan Senior Member Join Date: March 14, 2010 Location: Central Florida Posts: 813	9x25 Dillon

February 26, 2012, 03:08 PM	#5
Goldy Senior Member Join Date: May 23, 2004 Posts: 163	9X25 Dillon didn't need to be a high pressure round. It only had to push a 125 grain bullet to 1410fps to make major. It didn't last because of magazine capacity was less than 38 Super.

February 26, 2012, 08:07 PM	#8
Toxdoc Senior Member Join Date: June 5, 2008 Posts: 106	It is easy to get into: Glock 20 Lone Wolf Conversion barrel (not a bad idea to put in a stiffer recoil spring) I think double tap is the only commercial loader for the round. Dillon sells dies and they aren't cheap. Finding 10mm brass is the toughest part.