Bullet Sizing

StainlessButcher · December 19, 2009, 12:31 AM

Is bullet sizing standard procedure for every cast bullet, or are my suspicions correct that it's more of a fine tuning thing than a necessity thing?

Butch.

USMC Vet · December 19, 2009, 03:16 PM

Cast bullets need to be sized for the optimum diameter of firearm's bore.
Normally, this would be at exact bore dia. or .001 larger than bore dia. Also, during the sizing process, the sizer would be applying bullet lube into the lube groove(s), unless you use a tumble lube process. No, sizing is not a hit or miss operation, but a necessary part of reloading cast bullets.
Hope this helps.
USMC Vet

Nate1778 · December 19, 2009, 03:29 PM

To an extent, sizing is done so the bullet chambers. I can cast for my GP100 without sizing no problems. I think it throws at .360. My 9mm has to be sized to .356 to chamber fully. .357 and it will not. The rule I understand it as is if it chambers, shoot it. If it don't size it. As Mr. Lee put it in his book, there is no better sizer than the barrel of the gun.

snuffy · December 19, 2009, 03:49 PM

Quote:

Is bullet sizing standard procedure for every cast bullet,

No to that question. The exception concerns lee tumble lubed bullets, they're made to more closely fit most bores with thin driving bands that adapt easily to smaller bores. The lube grooves are very shallow so they hold the lee liquid alox better.

Quote:

or are my suspicions correct that it's more of a fine tuning thing than a necessity thing?

Yes, no, maybe to that general question. Or it depends. Cast bullets need to fit the bore of a firearm, most do best when sized 1 to 2 thousandths over bore diameter. You determine bore diameter by "slugging" the bore, forcing a soft lead slug that's over bore diameter through your barrel. In a revolver, you also have to know the cylinder throat diameter. Cast bullets cannot be undersized, they will lead like crazy and possibly strip when trying to be grabbed by the rifling.

wncchester · December 19, 2009, 05:58 PM

IF you can chamber a cartridge normally with your unsized bullet in place, it's safe. The bullet will be perfectly sized by the time it moves it's own length into the bore.

I believe the bullet lube is the single greatest factor in good shooting cast bullets. It makes up somewhat for bad sizing or a bad alloy or excessive speeds. I doubt any lube is better than the NRA formula of Allox:Beeswax, and few are as good.

Rangefinder · December 20, 2009, 04:45 AM

Sizing is all of the above, and on occasion not necessary at all. I cast for my .32 win Special loading what I drop straight out of the mold (lubed, but not sized). My mold drops clean, well-rounded, and correct to my bore. If it ain't broke, don't fix it. Now, with my .357, the mold is over by about a thousandth to what will load smooth. I run it through the sizer, and it lubes, trues up the roundness, and everything runs smoothly. Without the sizer on that one, I stretch the neck of the case too much or end up shaving lead and gunking up my dies.

StainlessButcher · December 21, 2009, 12:10 AM

I think I'm eventually going to invest in some casting equipment, but I'll "slug" my barrel and see what I get once I get some bullets here. Do you measure the throat area of a revolver on top of the rifling or between them? I would assume between, but you know what they say about assumptions....makes an a** out of you and umption.

Butch.

twice barrel · December 21, 2009, 11:26 AM

Drive a bullet thru the bore or pour a lap and push it thru. You measure the tightest part of the bore.

TB

Jim Watson · December 21, 2009, 11:42 AM

The English language has gone to hell on the internet.
There is no connection between bullet diameter and BORE diameter*.
Bullets should fill the GROOVE diameter; a thousandth or two larger for cast bullets.
Revolver bullets should fill or closely approach cylinder throat diameter. Ideally the cylinder throat(s) should be at or very slightly over groove diameter. If the throat is larger than groove diameter it is best to fit the cylinder and let the bullet be squeezed down in the barrel. If the throat is smaller than groove diameter, you need a gunsmith.

*Unless you are shooting paper patched bullets over black powder.

December 19, 2009, 12:31 AM	#1
StainlessButcher Member Join Date: December 15, 2009 Posts: 52	Bullet Sizing Is bullet sizing standard procedure for every cast bullet, or are my suspicions correct that it's more of a fine tuning thing than a necessity thing? Butch.

December 19, 2009, 03:16 PM	#2
USMC Vet Member Join Date: April 20, 2009 Location: S.E. New Hampshire Posts: 30	Bullet sizing Cast bullets need to be sized for the optimum diameter of firearm's bore. Normally, this would be at exact bore dia. or .001 larger than bore dia. Also, during the sizing process, the sizer would be applying bullet lube into the lube groove(s), unless you use a tumble lube process. No, sizing is not a hit or miss operation, but a necessary part of reloading cast bullets. Hope this helps. USMC Vet

December 19, 2009, 03:29 PM	#3
Nate1778 Senior Member Join Date: January 21, 2009 Location: Louisville Ky Posts: 312	To an extent, sizing is done so the bullet chambers. I can cast for my GP100 without sizing no problems. I think it throws at .360. My 9mm has to be sized to .356 to chamber fully. .357 and it will not. The rule I understand it as is if it chambers, shoot it. If it don't size it. As Mr. Lee put it in his book, there is no better sizer than the barrel of the gun. __________________ "And finally, the Baby Bear looked and he said, "Somebody's sleeping in my bed, and the bastard's still there!" But Goldylocks had a Remington semi-automatic, with a scope and a hair-trigger!"

December 19, 2009, 05:58 PM	#5
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	IF you can chamber a cartridge normally with your unsized bullet in place, it's safe. The bullet will be perfectly sized by the time it moves it's own length into the bore. I believe the bullet lube is the single greatest factor in good shooting cast bullets. It makes up somewhat for bad sizing or a bad alloy or excessive speeds. I doubt any lube is better than the NRA formula of Allox:Beeswax, and few are as good.

December 20, 2009, 04:45 AM	#6
Rangefinder Senior Member Join Date: August 4, 2005 Posts: 2,017	Sizing is all of the above, and on occasion not necessary at all. I cast for my .32 win Special loading what I drop straight out of the mold (lubed, but not sized). My mold drops clean, well-rounded, and correct to my bore. If it ain't broke, don't fix it. Now, with my .357, the mold is over by about a thousandth to what will load smooth. I run it through the sizer, and it lubes, trues up the roundness, and everything runs smoothly. Without the sizer on that one, I stretch the neck of the case too much or end up shaving lead and gunking up my dies.

December 21, 2009, 12:10 AM	#7
StainlessButcher Member Join Date: December 15, 2009 Posts: 52	I think I'm eventually going to invest in some casting equipment, but I'll "slug" my barrel and see what I get once I get some bullets here. Do you measure the throat area of a revolver on top of the rifling or between them? I would assume between, but you know what they say about assumptions....makes an a** out of you and umption. Butch.

December 21, 2009, 11:26 AM	#8
twice barrel Member Join Date: November 11, 2009 Posts: 98	Drive a bullet thru the bore or pour a lap and push it thru. You measure the tightest part of the bore. TB

December 21, 2009, 11:42 AM	#9
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 19,187	The English language has gone to hell on the internet. There is no connection between bullet diameter and BORE diameter. Bullets should fill the GROOVE diameter; a thousandth or two larger for cast bullets. Revolver bullets should fill or closely approach cylinder throat diameter. Ideally the cylinder throat(s) should be at or very slightly over groove diameter. If the throat is larger than groove diameter it is best to fit the cylinder and let the bullet be squeezed down in the barrel. If the throat is smaller than groove diameter, you need a gunsmith. Unless you are shooting paper patched bullets over black powder.