Bore Diameter: Win 43. 32-20

The Jaeger · December 16, 2012, 08:08 PM

What is the bore diameter of a Winchester Model 43 32-20? Is it .308 or
.312?

FrankenMauser · December 16, 2012, 08:11 PM

It should be .312".

salvadore · December 16, 2012, 08:54 PM

It could be as large as .314, my modern Marlin 32/20 is .313 and it shoots .314s very well. I have a Colt OP 32/20 that needs .314 bullets. Very accurate.

rodfac · December 18, 2012, 10:05 AM

You can guess or take the factory spec's (0.312") or slug the bore. To slug the bore, I use a muzzle loading round ball of pure lead, roll it over a piece of counter top to make an oblong shape slightly bigger than the bore, then tap it down the barrel. I use CLP or any good gun oil in the bore to ease it's passage and a piece of dowel rod to do the work once the ball is started in the muzzle. Measure the slug as it emerges with a micrometer across the impressed lands and you're good to go.

For hand loading, any good .32 bullet works well; in my experience, Hornady's XTP's are good, as are the Sierra and Speer offerings. I'v'e worked with 85 to 100 gr jacketed bullet with my 1925 vintage Winchester M-92, and also through a S&W hand ejector 4th model of the same vintage. The Model 92 will stay in an inch and a half at 50 yds with a peep sight off a rest. The Smith will do the same at 25 yds.

2400, Unique, Blue Dot, and Winchester 231 do well with either cast or jacketed bullets. For cast, I size them .312" and have good luck with minimal leading with either gun (and that M-92 has less than a pristine bore).

That Winchester 43 has a good rep for accuracy...Ken Waters did a work up on a Savage 23C (very similar to the Winchester), in May of '89 that really peaked my interest, and that you might find useful...his work was published by Wolfe Publishing in Supplement #4 to Ken's "Pet Loads" book. He too sized his cast bullets to 0.312" and reported excellent accuracy with Remington, Hornady and Sierra jacketed bullets. Good luck with your project.

HTH's Rod

December 16, 2012, 08:08 PM	#1
The Jaeger Junior Member Join Date: February 22, 2009 Location: Southwestern PA Posts: 4	Bore Diameter: Win 43. 32-20 What is the bore diameter of a Winchester Model 43 32-20? Is it .308 or .312?

December 16, 2012, 08:11 PM	#2
FrankenMauser Senior Member Join Date: August 26, 2008 Location: 1B ID Posts: 5,415	It should be .312". __________________ "Such is the strange way that man works -- first he virtually destroys a species and then does everything in his power to restore it."

December 16, 2012, 08:54 PM	#3
salvadore Senior Member Join Date: January 1, 2007 Location: Idaho Posts: 1,374	It could be as large as .314, my modern Marlin 32/20 is .313 and it shoots .314s very well. I have a Colt OP 32/20 that needs .314 bullets. Very accurate.

December 18, 2012, 10:05 AM	#4
rodfac Senior Member Join Date: January 22, 2005 Location: Kentucky Posts: 1,240	You can guess or take the factory spec's (0.312") or slug the bore. To slug the bore, I use a muzzle loading round ball of pure lead, roll it over a piece of counter top to make an oblong shape slightly bigger than the bore, then tap it down the barrel. I use CLP or any good gun oil in the bore to ease it's passage and a piece of dowel rod to do the work once the ball is started in the muzzle. Measure the slug as it emerges with a micrometer across the impressed lands and you're good to go. For hand loading, any good .32 bullet works well; in my experience, Hornady's XTP's are good, as are the Sierra and Speer offerings. I'v'e worked with 85 to 100 gr jacketed bullet with my 1925 vintage Winchester M-92, and also through a S&W hand ejector 4th model of the same vintage. The Model 92 will stay in an inch and a half at 50 yds with a peep sight off a rest. The Smith will do the same at 25 yds. 2400, Unique, Blue Dot, and Winchester 231 do well with either cast or jacketed bullets. For cast, I size them .312" and have good luck with minimal leading with either gun (and that M-92 has less than a pristine bore). That Winchester 43 has a good rep for accuracy...Ken Waters did a work up on a Savage 23C (very similar to the Winchester), in May of '89 that really peaked my interest, and that you might find useful...his work was published by Wolfe Publishing in Supplement #4 to Ken's "Pet Loads" book. He too sized his cast bullets to 0.312" and reported excellent accuracy with Remington, Hornady and Sierra jacketed bullets. Good luck with your project. HTH's Rod __________________ Our Flag does not fly because the wind blows against it, It proudly waves because a soldier's dying breath blows upon it. USAF Forward Air Controller, 5th Spl Forces, An Loc, lll Corps, RVN, 69-70, Vietnam Vet '69-'73