How Often Are Most Cases Used Before Trimming?

BntBrl · June 22, 2008, 05:16 PM

I have reloaded these casings 2 times after having fired them from factory weatherby ammo. I measured them and they are all at or about the trim to size. A couple of them are just a little underneath the trim to size. I measured them after they were fired in my rifle. I dont know if this is normal or not. I have used fairly light loads, at least in the middle of, from the reloading manual (Lyman). Perhaps this is why?

How many times is it common to not have to trim the length of casings? I was under the impression it was 1 or two firings, but this looks like the third firing.

I am shooting these out of a .300 Weatherby Vanguard.

dmickey · June 22, 2008, 05:30 PM

As long as the case length is under the maximum don't worry about it! Don't neglect measuring them each time you go to reload them however! It sounds like you are measuring the exact length each time. All you have to do is to set your dial caliper (or whatever you are using) to the maximum length and make sure that the cases fit through the measuring surfaces. I one time neglected measuring some .220 Swift cases and ended up having to toss them because of spilts caused by allowing them to grow too long!

Slamfire · June 22, 2008, 06:31 PM

Measure them after sizing. Sizing alters the length of the neck.

I trim after each firing with my rifle ammo. I found out that you have to check case length because cases grow with firings. My cases lengthen the most after the first firing.

A long case neck will creep up into the throat and pinch the bullet. This caused blown primers for me. Then I got the tools to trim cases and life has been good.

If however, after sizing they are under max length, the cases don't need trimming.

BntBrl · June 22, 2008, 07:37 PM

Ok. I didnt know if there was something else to it I was missing or something. I pulled out the trimmer to trim them and they didnt need it apparently. This will be the third time I fire them.

Thanks

rn22723 · June 26, 2008, 04:11 PM

The weatherby case design with the double radius shoulder probably helps decrease brass flow as apposed to some shell designes which sort of encourage brass flow from firing. Resizing of course does cause some lengthening of the cases, too. Makeing sure to lube inside the case neck and perhaps using a carbide expander ball would help with this.....another thought since using a bolt gun, is go to using a bushing die to resize the case neck, this would eliminate the use of the expander ball.....

ISC · June 26, 2008, 04:25 PM

The powder charge will affect creep as will whether you full length resize or just case neck resize. I've never loaded .300 weatherby, but I know those factors affect .308 and .223.

BntBrl · June 26, 2008, 08:15 PM

i am full sizing them right now. i have a neck resizer coming. i read that when using them for hunting its best to full resize them. i plan to use it for hunting. i shoot it a lot at the range on the bench. i started shooting more from standing position.

tuck2 · June 29, 2008, 01:55 AM

I neck size belted cases after the cases are first fireformed to the chamber. I then trim the cases to the size listed in a reloading manual. I try a case in the rifle chamber if the is no problem closeing the bolt I then reload the case. I reload the 7 MM Rem Mag, 308 Norma Mag, and 340 Weatherby Mag rounds. I trim the cases after reloading them about four times, but I check the length after each fireing to see if any of the cases are over the Max length.

BntBrl · June 29, 2008, 02:32 AM

Some of them this is the fourth reloading and still no need to trim them. Thats fine with me as long as they are within specs and safe.

I got my cartridge spacing gage in today and theres several of my brass that the belt doesnt want to go in the gage. It makes it easy to check them quickly but I guess the belt has expanded and the resizer doesnt fully compress the belt. I got my neck sizer in today also.

**44 AMP** · June 29, 2008, 10:09 PM

And the pressure of the loading makes a difference as well. There is no set number, just measure the case, and when it approaches max length, trim it.

Straight wall cases often grow very slowly, and sometimes not at all. Bottlenecked high intensity calibers tend to grow faster. Generally, cases grow the most (in length) on their first firing, and grow less length each firing after that.

The trim-to length is not a magic number, simply a convienient one for uniformity. Max case length is an important number, because when the brass gets too long, it cannot properly expand to release the the bullet, and pressure spikes up. This is not considered to be a good thing, so we avoid it by trimming our brass, when needed.

June 22, 2008, 05:16 PM	#1
BntBrl Member Join Date: June 8, 2008 Posts: 95	How Often Are Most Cases Used Before Trimming? I have reloaded these casings 2 times after having fired them from factory weatherby ammo. I measured them and they are all at or about the trim to size. A couple of them are just a little underneath the trim to size. I measured them after they were fired in my rifle. I dont know if this is normal or not. I have used fairly light loads, at least in the middle of, from the reloading manual (Lyman). Perhaps this is why? How many times is it common to not have to trim the length of casings? I was under the impression it was 1 or two firings, but this looks like the third firing. I am shooting these out of a .300 Weatherby Vanguard.

June 29, 2008, 10:09 PM	#10
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 30,480	Each caliber is different And the pressure of the loading makes a difference as well. There is no set number, just measure the case, and when it approaches max length, trim it. Straight wall cases often grow very slowly, and sometimes not at all. Bottlenecked high intensity calibers tend to grow faster. Generally, cases grow the most (in length) on their first firing, and grow less length each firing after that. The trim-to length is not a magic number, simply a convienient one for uniformity. Max case length is an important number, because when the brass gets too long, it cannot properly expand to release the the bullet, and pressure spikes up. This is not considered to be a good thing, so we avoid it by trimming our brass, when needed. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

June 22, 2008, 05:30 PM	#2
dmickey Senior Member Join Date: January 18, 2006 Posts: 124	As long as the case length is under the maximum don't worry about it! Don't neglect measuring them each time you go to reload them however! It sounds like you are measuring the exact length each time. All you have to do is to set your dial caliper (or whatever you are using) to the maximum length and make sure that the cases fit through the measuring surfaces. I one time neglected measuring some .220 Swift cases and ended up having to toss them because of spilts caused by allowing them to grow too long!

June 22, 2008, 06:31 PM	#3
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	Measure them after sizing. Sizing alters the length of the neck. I trim after each firing with my rifle ammo. I found out that you have to check case length because cases grow with firings. My cases lengthen the most after the first firing. A long case neck will creep up into the throat and pinch the bullet. This caused blown primers for me. Then I got the tools to trim cases and life has been good. If however, after sizing they are under max length, the cases don't need trimming.

June 22, 2008, 07:37 PM	#4
BntBrl Member Join Date: June 8, 2008 Posts: 95	Ok. I didnt know if there was something else to it I was missing or something. I pulled out the trimmer to trim them and they didnt need it apparently. This will be the third time I fire them. Thanks

June 26, 2008, 04:11 PM	#5
rn22723 Junior member Join Date: December 10, 2001 Location: Burbs of Minneapolis Posts: 676	The weatherby case design with the double radius shoulder probably helps decrease brass flow as apposed to some shell designes which sort of encourage brass flow from firing. Resizing of course does cause some lengthening of the cases, too. Makeing sure to lube inside the case neck and perhaps using a carbide expander ball would help with this.....another thought since using a bolt gun, is go to using a bushing die to resize the case neck, this would eliminate the use of the expander ball.....

June 26, 2008, 04:25 PM	#6
ISC Junior member Join Date: August 5, 2007 Location: Florida Posts: 1,982	The powder charge will affect creep as will whether you full length resize or just case neck resize. I've never loaded .300 weatherby, but I know those factors affect .308 and .223.

June 26, 2008, 08:15 PM	#7
BntBrl Member Join Date: June 8, 2008 Posts: 95	i am full sizing them right now. i have a neck resizer coming. i read that when using them for hunting its best to full resize them. i plan to use it for hunting. i shoot it a lot at the range on the bench. i started shooting more from standing position.

June 29, 2008, 01:55 AM	#8
tuck2 Senior Member Join Date: April 25, 2007 Posts: 208	I neck size belted cases after the cases are first fireformed to the chamber. I then trim the cases to the size listed in a reloading manual. I try a case in the rifle chamber if the is no problem closeing the bolt I then reload the case. I reload the 7 MM Rem Mag, 308 Norma Mag, and 340 Weatherby Mag rounds. I trim the cases after reloading them about four times, but I check the length after each fireing to see if any of the cases are over the Max length.

June 29, 2008, 02:32 AM	#9
BntBrl Member Join Date: June 8, 2008 Posts: 95	Some of them this is the fourth reloading and still no need to trim them. Thats fine with me as long as they are within specs and safe. I got my cartridge spacing gage in today and theres several of my brass that the belt doesnt want to go in the gage. It makes it easy to check them quickly but I guess the belt has expanded and the resizer doesnt fully compress the belt. I got my neck sizer in today also.