Neck Sizing .357 magnum cases

Boo586 · November 6, 2001, 02:24 PM

Just got a good pair of calipers for my birthday, thanks to my father-in-law. I was just spending my lunch at home measuring some resized cases and some unresized fired cases. The resized cases measure 0.372 inches in diameter. Some .38 special cases measure 0.375 inches and some once fired .357 magnum brass measures 0.381. The chambers of my revolver measure about 0.382 inches to best of my ability. After I mesured these I chambered each one of the cases one at a time to see how the cases fit in the chambers. The resized case and the .38 special case moved around in the chamber a lot, while the once fired magnum brass fit snug but did not have to be forced into the chambers.

Using the unsized cases should keep my pressures lower and be easier on my gun with my hunting loads. I am also thinking that the snug fit of the cases in the chaber will help to align the bullet with the barrel and increase the gun's accuracy. For the few cases that have to be pushed into the chamber I am going to try and resize the cases by rolling the cases between two metal plates to remove any slight bulges that might be present. Then I am just going to neck size the cases where they hold the bullet and then crimp heavily.

Has anybody done this and is my thinking along the correct lines, or am I way off base?

Thanks for the Help!!

Boo586

Jeeper · November 6, 2001, 02:32 PM

I am not sure how much of a true "neck size" you can do with pistol dies. I have never tried it or thought to. Since the bottom of the brass is usuall the largest area your brass still might be a little to tight. I have never had any accuracy problems by full length sizing brass and having a loose cylinder. I have a 357 FA that I use for pistol silhouette at 200 yards and it has always performed well using full length sizing. You could always try it and see what happens. You could also try full lengh sizing and see how they compare accuracy wise. I personally hate havig to shove ammo into a revolver. I prefer an easy fit.

Ben Shepherd · November 6, 2001, 02:39 PM

check the thread on magnum primers. Read Steve Smiths comments.

Bogie · November 6, 2001, 06:48 PM

You'll see a bigger increase in accuracy if you get a good tight crimp... I wouldn't mess with "roll sizing" pistol ammo.

canuck2 · December 19, 2001, 06:31 PM

Hi, I don't have pistol experience but my feeling from working at HIGH pressures with 6PPC benchrest is that sized cases will give you lower pressure not higher, because the brass has some room to give, absorbing some energy while expanding. At least With 6PPC and I suspect in general this has more effect than that of a very small difference in cartridge volume which I suspect you are considering.
Regards, Ed

November 6, 2001, 02:24 PM	#1
Boo586 Member Join Date: May 15, 2001 Location: Indiana Posts: 85	Neck Sizing .357 magnum cases Just got a good pair of calipers for my birthday, thanks to my father-in-law. I was just spending my lunch at home measuring some resized cases and some unresized fired cases. The resized cases measure 0.372 inches in diameter. Some .38 special cases measure 0.375 inches and some once fired .357 magnum brass measures 0.381. The chambers of my revolver measure about 0.382 inches to best of my ability. After I mesured these I chambered each one of the cases one at a time to see how the cases fit in the chambers. The resized case and the .38 special case moved around in the chamber a lot, while the once fired magnum brass fit snug but did not have to be forced into the chambers. Using the unsized cases should keep my pressures lower and be easier on my gun with my hunting loads. I am also thinking that the snug fit of the cases in the chaber will help to align the bullet with the barrel and increase the gun's accuracy. For the few cases that have to be pushed into the chamber I am going to try and resize the cases by rolling the cases between two metal plates to remove any slight bulges that might be present. Then I am just going to neck size the cases where they hold the bullet and then crimp heavily. Has anybody done this and is my thinking along the correct lines, or am I way off base? Thanks for the Help!! Boo586

November 6, 2001, 02:39 PM	#3
Ben Shepherd Senior Member Join Date: August 11, 2001 Location: Utah Posts: 1,462	check the thread on magnum primers. Read Steve Smiths comments. __________________ From my cold dead hands......... NRA certified rifle, pistol and shotgun instructor. Hunter education instructor

November 6, 2001, 06:48 PM	#4
Bogie Senior Member Join Date: June 5, 2000 Location: Job hunting on the road... Posts: 3,827	You'll see a bigger increase in accuracy if you get a good tight crimp... I wouldn't mess with "roll sizing" pistol ammo. __________________ Job hunting, but helping a friend out at www.vikingmachineusa.com - and learning the finer aspects of becoming a precision machinist. And making the world's greatest bottle openers!

November 6, 2001, 02:32 PM	#2
Jeeper Senior Member Join Date: November 1, 2001 Location: Gilbert, AZ Posts: 776	I am not sure how much of a true "neck size" you can do with pistol dies. I have never tried it or thought to. Since the bottom of the brass is usuall the largest area your brass still might be a little to tight. I have never had any accuracy problems by full length sizing brass and having a loose cylinder. I have a 357 FA that I use for pistol silhouette at 200 yards and it has always performed well using full length sizing. You could always try it and see what happens. You could also try full lengh sizing and see how they compare accuracy wise. I personally hate havig to shove ammo into a revolver. I prefer an easy fit.

December 19, 2001, 06:31 PM	#5
canuck2 Junior Member Join Date: December 19, 2001 Posts: 9	Hi, I don't have pistol experience but my feeling from working at HIGH pressures with 6PPC benchrest is that sized cases will give you lower pressure not higher, because the brass has some room to give, absorbing some energy while expanding. At least With 6PPC and I suspect in general this has more effect than that of a very small difference in cartridge volume which I suspect you are considering. Regards, Ed