Whats the difference Flat base or not

JLK · May 22, 2008, 04:47 PM

I was looking at some winchester 9mm bullets to reload. 115 gr. fmj. some were listed as flat base and some were not. What is the difference and will one be more accurate than the other?

Grandpa Shooter · May 22, 2008, 07:39 PM

Flat base means there is no bevel on the edges of the base to ease in loading, but on a pistol caliber it shouldn't make any difference. You will be belling the case mouth anyway.

nitesite9 · May 25, 2008, 09:33 PM

Flat base bullets create a better (tighter) seal against the bore. Bevel based bullets are easier to use in progressive and commercial loaders because they enter the case mouth more reliably, but they don't obturate as well.

zeke · May 26, 2008, 07:01 AM

Winchester also makes a hollow (concave) base 115 grain 9mm bullet. It has a concave base with the jacket just sealed over the outer edge, leaving exposed lead in the concave portion. Last time i checked, it is the same bullet used in Winchester Q4172 factory rounds. Every 9mm owned is very accurate with the Q4172 rounds, and i suspect the concave soft lead base gets pushed out to better engrave the jacketing against the rifling. Am also guessing this feature was designed delibrately.

Bought a couple thosand of these concave base bullets when they were on sale awhile back, but ain't loaded any yet.

May 22, 2008, 04:47 PM	#1
JLK Senior Member Join Date: October 1, 2001 Posts: 135	Whats the difference Flat base or not I was looking at some winchester 9mm bullets to reload. 115 gr. fmj. some were listed as flat base and some were not. What is the difference and will one be more accurate than the other? __________________ Rsrc

May 22, 2008, 07:39 PM	#2
Grandpa Shooter Senior Member Join Date: November 13, 2007 Posts: 140	Flat base means there is no bevel on the edges of the base to ease in loading, but on a pistol caliber it shouldn't make any difference. You will be belling the case mouth anyway. __________________ Old enough to know better and way too old to care!

May 25, 2008, 09:33 PM	#3
nitesite9 Member Join Date: February 4, 2008 Location: Morgan County, Alabama Posts: 29	Flat base bullets create a better (tighter) seal against the bore. Bevel based bullets are easier to use in progressive and commercial loaders because they enter the case mouth more reliably, but they don't obturate as well. __________________ Deputy Sheriff 1983-1985 Regular Army 1985-1993 E-7 NRA Member

May 26, 2008, 07:01 AM	#4
zeke Senior Member Join Date: November 17, 1999 Location: NW Wi Posts: 1,671	Winchester also makes a hollow (concave) base 115 grain 9mm bullet. It has a concave base with the jacket just sealed over the outer edge, leaving exposed lead in the concave portion. Last time i checked, it is the same bullet used in Winchester Q4172 factory rounds. Every 9mm owned is very accurate with the Q4172 rounds, and i suspect the concave soft lead base gets pushed out to better engrave the jacketing against the rifling. Am also guessing this feature was designed delibrately. Bought a couple thosand of these concave base bullets when they were on sale awhile back, but ain't loaded any yet.