300 Win Mag

idriller · February 21, 2016, 09:39 AM

I just started loading for my 300 Win Mag. I've got a few questions about the cases. I purchased a shoulder bump gauge and belted magnum case gauge from Whidden gun works. I bumped the shoulders back on my fire formed brass a few thousandths but was wondering about the belt. They range from -.002 to -004 but a few of them were around -005 to -007. Is this some thing to worry about. Im not loading for 1000yds or anything just wanting a better understanding in relation to accuracy. Thanks in advance.

Greg Mercurio · February 21, 2016, 09:48 AM

The belt is an irrelevant relic, but still works charms for marketing purposes. Headspace on the shoulder and forget about the belt.

F. Guffey · February 21, 2016, 10:48 AM

Quote:

Thanks in advance.

I am surprised a reloader hasn’t already recommended a L. Willis height gage/comparator. Normally that recommendation is followed up by purchasing a collate? die.

I have one belted magnum rifle that matches my dies; that is something a reloader can not comprehend, and Winchester, forget talking to Winchester about fixing the problem. I am of the opinion reloadrs are staffing the CS phones

In the big inning the belt was designed to accomplish the same task as the rim; it was designed to hold the case to the rear of the chamber. After the belt replaced the rim anything that happened in from of the belt was of little consequence. No one had to get use to the belt because nothing changed, the rim held the case to the rear of the chamber and anything that happened in front of the rim was of little consequence.

F. Guffey

USMC 77-81 · February 21, 2016, 12:11 PM

Just for your knowledge, I shoot with a guy who has a .300 WM on a Tikka T3, he regularly shoots 3 shot 1 hole groups at 100 yards, bangs the 600 yard gong and drops Elk yearly.

mikejonestkd · February 21, 2016, 12:33 PM

I reload for my brother's Remington 700 in 300 win mag.
using once fired brass we just barely touch the shoulder with the sizing die- essentially headspacing this rifle off the shoulder.
The belt has never been a factor to be considered for this rifle, your mileage might vary.

condor bravo · February 21, 2016, 12:38 PM

As Greg pointed out, try to adjust your die for headspacing on the shoulder to prevent excessive case stretching upon each firing.

idriller · February 21, 2016, 01:50 PM

I currently just bump the shoulder back just a few thousands. At the most maybe .003. I then check to make sure it will chamber in my rifle.

Clark · February 22, 2016, 01:12 AM

I shot a buck in October with a Mosin Nagant I converted to 300 Win Mag with a Krieger barrel I got for cheap when someone put the wrong threads on the muzzle. I got the stock off Ebay.

Anyway 125 gr Nosler Ballistic Tip, I moly coated the bullet, 66 gr IMR-4166, 3.34" OAL, ~ 3165 fps ~ 47kpsi.

I had it sighted in and shooting well out to 500 yards, but this shot was at a running buck at 250 yards.

February 21, 2016, 09:39 AM	#1
idriller Junior Member Join Date: December 8, 2014 Posts: 12	300 Win Mag I just started loading for my 300 Win Mag. I've got a few questions about the cases. I purchased a shoulder bump gauge and belted magnum case gauge from Whidden gun works. I bumped the shoulders back on my fire formed brass a few thousandths but was wondering about the belt. They range from -.002 to -004 but a few of them were around -005 to -007. Is this some thing to worry about. Im not loading for 1000yds or anything just wanting a better understanding in relation to accuracy. Thanks in advance.

February 21, 2016, 09:48 AM	#2
Greg Mercurio Senior Member Join Date: December 5, 2010 Posts: 151	The belt is an irrelevant relic, but still works charms for marketing purposes. Headspace on the shoulder and forget about the belt. __________________ Old guy and NRA Life Member

February 21, 2016, 12:33 PM	#5
mikejonestkd Senior Member Join Date: January 3, 2006 Location: Brockport, NY Posts: 3,716	I reload for my brother's Remington 700 in 300 win mag. using once fired brass we just barely touch the shoulder with the sizing die- essentially headspacing this rifle off the shoulder. The belt has never been a factor to be considered for this rifle, your mileage might vary. __________________ You are the bows from which your children as living arrows are sent forth.

February 21, 2016, 12:38 PM	#6
condor bravo Senior Member Join Date: August 23, 2014 Location: Nevada/Ariz/CA Posts: 1,753	As Greg pointed out, try to adjust your die for headspacing on the shoulder to prevent excessive case stretching upon each firing. __________________ Ouch, the dreaded "M-1 thumb", you just know it will happen eventually, so why not do it now and get it over with??

February 22, 2016, 01:12 AM	#8
Clark Senior Member Join Date: December 4, 1999 Location: WA, the ever blue state Posts: 4,678	I shot a buck in October with a Mosin Nagant I converted to 300 Win Mag with a Krieger barrel I got for cheap when someone put the wrong threads on the muzzle. I got the stock off Ebay. Anyway 125 gr Nosler Ballistic Tip, I moly coated the bullet, 66 gr IMR-4166, 3.34" OAL, ~ 3165 fps ~ 47kpsi. I had it sighted in and shooting well out to 500 yards, but this shot was at a running buck at 250 yards. __________________ The word 'forum" does not mean "not criticizing books." "Ad hominem fallacy" is not the same as point by point criticism of books. If you bought the book, and believe it all, it may FEEL like an ad hominem attack, but you might strive to accept other points of view may exist. Are we a nation of competing ideas, or a nation of forced conformity of thought?

February 21, 2016, 12:11 PM	#4
USMC 77-81 Senior Member Join Date: February 6, 2012 Location: Northern Idaho Posts: 254	Just for your knowledge, I shoot with a guy who has a .300 WM on a Tikka T3, he regularly shoots 3 shot 1 hole groups at 100 yards, bangs the 600 yard gong and drops Elk yearly.

February 21, 2016, 01:50 PM	#7
idriller Junior Member Join Date: December 8, 2014 Posts: 12	I currently just bump the shoulder back just a few thousands. At the most maybe .003. I then check to make sure it will chamber in my rifle.