importance of case trimming

rbf420 · October 21, 2009, 08:51 AM

ive been reloading for a couple of months now, i have seen many accesories to trim cases and read very little about it. how important is it actually to trim cases? if im loading 30.06, .38spl, .357, and 9mm are there ones more important to trim than others? does it really effect bullets that much or is it more asthetics?

McClintock · October 21, 2009, 10:25 AM

I only ever trim rifle brass.

I don't think I've ever trimmed pistol brass, it never sticks around long enough.

I believe it's quite important to trim your rifle cases. Rifle brass tends to stretch after a couple of firings (depending on the brass, of course, some manufacturer's cases stretch more than others, I've found), and Really Bad Things can happen if you use brass that is too long. If you keep using the same brass without trimming it, eventually the brass could get so long that the neck of the brass will reach all the way forward until it can reach the beginning of the rifling. If it does this, it can "pinch" the bullet in the case and cause very high pressures and even case or primer failure.

It also helps in accuracy if all your cases are consistent, trimmed to the same length.

Hope that helps.

Cheers!
McClintock

crimsondave · October 21, 2009, 10:37 AM

I trim all my cases to the same legnth, even pistol. It makes a difference in accuracy on rifles, but honestly, you could probably skip it on loading pistol.

One issue I had with 45-70 worth mentioning was that I was buckelling cases that were slightly longer that I had forgotten to trim while crimping with the seater die.

Foxbat · October 21, 2009, 11:30 AM

Never trimmed a case in my life, not even rifle, and never had any issues in almost 30 years I have been reloading... who knows how many rounds I shot over those years, but these days I typically shoot 800 per week.

jal5 · October 21, 2009, 11:34 AM

I found that trimming 357 mag cases made a difference for me, at least in hunting rounds. Don't think I would bother with rounds made for target/plinking though in pistol calibers.

Farmland · October 21, 2009, 11:40 AM

I have never found a reason to trim pistol cases so I don't.

I do trim all of my 223 for my AR. The main reason is I absolutely get I better constant OAL for the loaded rounds.

I do trim for my hunting loads on the 30-06 and 25-06 and the result is that when I trim the same cases the groups are much tighter in addition the OAL is constant. I set my bullets high so the trimming helps to make sure the bullet is where I want it to be.

That is why I trim but the most important I feel are the 223's for the AR. This insures that each round will fit through the gun and cycle plus I feel because the OAL is constant the pressure of each round is pretty much constant. To me that is important.

SL1 · October 21, 2009, 12:21 PM

As McClintok wrote, bad things can happen if you let your cases get long enough that they get jammed into the CHAMBER THROAT (not rifling) and cannot release the bullet until pressue gets high. Bottleneck rifle catridges stretch more than other cartridge types, and also usually have higher pressures, too. So, they are the ones that are most likely to cause trouble, and that trouble can be dangerous to your gun, yourself and bystanders, too.

If you are relaoding and not CHECKING your bottleneck rifle cases to be sure they are not exceeding your rifles chamber length (to the point where your throat begins) then you are taking a chance. Many folks never actually measure their cahnbers and just make sure they don't exceed SAAMI max case lengths, and that is safe enough because all chambers will be longer than that.

plainsman456 · October 21, 2009, 02:59 PM

Never had to trim pistol but sure do rifle cases.Good Luck

Ivan · October 21, 2009, 03:14 PM

If you hate trimming cases, trim them once and use a RCBS X-die. It adjusts the length when it resizes the case which is the step that actually causes the case length to increase. I own a couple but have never used them, so all I am quoting here is the advertising.

- Ivan.

azredhawk44 · October 21, 2009, 03:21 PM

Quote:

If you hate trimming cases, trim them once and use a RCBS X-die. It adjusts the length when it resizes the case which is the step that actually causes the case length to increase. I own a couple but have never used them, so all I am quoting here is the advertising.

Using an X-die right now.

It might work for bolt gunners, but when you have an automatic rifle like an M14 or AR, you still experience some case growth.

I'll admit I'm only a couple hundred rounds into my experience with the die and I'll happily be proven wrong if my experiences change, though. It could be the brass I'm using right now... when I start a new batch of brass I'll approach it with an open mind.

TRguy · October 21, 2009, 03:24 PM

I trim rifle cause I was taught too.....went without doing for a few shootings and groups widened.....trimmed the cases and my groups tightened back up

I dont know what happened in the upper left group, they were so far apart....yeah I know that was for last year....couldn't find more recent range photo

Pistol? Never trim it

McClintock · October 21, 2009, 03:56 PM

Oops.

As SL1 said, not the rifling but the chamber throat.

Thanks for correcting me.

Cheers!
McClintock

gearheadpyro · October 21, 2009, 06:17 PM

Always trim rifle rounds, every time fired. I started crimping the bullets lately and noticed this causes the cases to stretch a bit more than not crimping.

As for pistol, I never trim it. I use the Lee factory crimp die and it post sizes the brass back down to the correct size. Very handy die, I'll not load without mine.

joneb · October 22, 2009, 12:56 AM

I trim all my rifle brass.
I trim my revolver brass to insure a consistent roll crimp.
I rarely trim auto pistol brass.

Hook686 · October 22, 2009, 01:55 AM

I do not trim revolver magnum brass, as it spaces off the rim. I do check and trim, as needed, rimless brass. My only brass that has really fallen into that catagory has been .30 carbine.

October 21, 2009, 08:51 AM	#1
rbf420 Senior Member Join Date: August 1, 2009 Posts: 166	importance of case trimming ive been reloading for a couple of months now, i have seen many accesories to trim cases and read very little about it. how important is it actually to trim cases? if im loading 30.06, .38spl, .357, and 9mm are there ones more important to trim than others? does it really effect bullets that much or is it more asthetics?

October 21, 2009, 11:34 AM	#5
jal5 Senior Member Join Date: January 12, 2009 Location: NE Ohio Posts: 419	I found that trimming 357 mag cases made a difference for me, at least in hunting rounds. Don't think I would bother with rounds made for target/plinking though in pistol calibers. __________________ We live in the greatest country on Earth- always be thankful!

October 21, 2009, 03:24 PM	#11
TRguy Senior Member Join Date: July 15, 2008 Location: Concord, NC Posts: 682	I trim rifle cause I was taught too.....went without doing for a few shootings and groups widened.....trimmed the cases and my groups tightened back up I dont know what happened in the upper left group, they were so far apart....yeah I know that was for last year....couldn't find more recent range photo Pistol? Never trim it __________________ Two is One, One is None

October 21, 2009, 03:56 PM	#12
McClintock Senior Member Join Date: December 5, 2008 Location: The Bald Prairie of Southern Saskatchewan, Canada Posts: 305	Correction Oops. As SL1 said, not the rifling but the chamber throat. Thanks for correcting me. Cheers! McClintock

October 21, 2009, 06:17 PM	#13
gearheadpyro Senior Member Join Date: September 3, 2009 Location: Charleston, SC Posts: 169	Always trim rifle rounds, every time fired. I started crimping the bullets lately and noticed this causes the cases to stretch a bit more than not crimping. As for pistol, I never trim it. I use the Lee factory crimp die and it post sizes the brass back down to the correct size. Very handy die, I'll not load without mine. __________________ www.southernmarksman.com Owner of & Chief Instructor for The Southern Marksman, LLC NRA Life Member, NRA CRSO, Multi-Discipline NRA Certified Instructor

October 21, 2009, 10:25 AM	#2
McClintock Senior Member Join Date: December 5, 2008 Location: The Bald Prairie of Southern Saskatchewan, Canada Posts: 305	I only ever trim rifle brass. I don't think I've ever trimmed pistol brass, it never sticks around long enough. I believe it's quite important to trim your rifle cases. Rifle brass tends to stretch after a couple of firings (depending on the brass, of course, some manufacturer's cases stretch more than others, I've found), and Really Bad Things can happen if you use brass that is too long. If you keep using the same brass without trimming it, eventually the brass could get so long that the neck of the brass will reach all the way forward until it can reach the beginning of the rifling. If it does this, it can "pinch" the bullet in the case and cause very high pressures and even case or primer failure. It also helps in accuracy if all your cases are consistent, trimmed to the same length. Hope that helps. Cheers! McClintock

October 21, 2009, 10:37 AM	#3
crimsondave Senior Member Join Date: September 30, 2009 Location: North Augusta, SC Posts: 490	I trim all my cases to the same legnth, even pistol. It makes a difference in accuracy on rifles, but honestly, you could probably skip it on loading pistol. One issue I had with 45-70 worth mentioning was that I was buckelling cases that were slightly longer that I had forgotten to trim while crimping with the seater die.

October 21, 2009, 11:30 AM	#4
Foxbat Senior Member Join Date: January 13, 2008 Posts: 367	Never trimmed a case in my life, not even rifle, and never had any issues in almost 30 years I have been reloading... who knows how many rounds I shot over those years, but these days I typically shoot 800 per week.

October 21, 2009, 11:40 AM	#6
Farmland Senior Member Join Date: July 5, 2009 Posts: 869	I have never found a reason to trim pistol cases so I don't. I do trim all of my 223 for my AR. The main reason is I absolutely get I better constant OAL for the loaded rounds. I do trim for my hunting loads on the 30-06 and 25-06 and the result is that when I trim the same cases the groups are much tighter in addition the OAL is constant. I set my bullets high so the trimming helps to make sure the bullet is where I want it to be. That is why I trim but the most important I feel are the 223's for the AR. This insures that each round will fit through the gun and cycle plus I feel because the OAL is constant the pressure of each round is pretty much constant. To me that is important.

October 21, 2009, 12:21 PM	#7
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	As McClintok wrote, bad things can happen if you let your cases get long enough that they get jammed into the CHAMBER THROAT (not rifling) and cannot release the bullet until pressue gets high. Bottleneck rifle catridges stretch more than other cartridge types, and also usually have higher pressures, too. So, they are the ones that are most likely to cause trouble, and that trouble can be dangerous to your gun, yourself and bystanders, too. If you are relaoding and not CHECKING your bottleneck rifle cases to be sure they are not exceeding your rifles chamber length (to the point where your throat begins) then you are taking a chance. Many folks never actually measure their cahnbers and just make sure they don't exceed SAAMI max case lengths, and that is safe enough because all chambers will be longer than that.

October 21, 2009, 02:59 PM	#8
plainsman456 Senior Member Join Date: December 31, 2008 Posts: 260	Never had to trim pistol but sure do rifle cases.Good Luck

October 21, 2009, 03:14 PM	#9
Ivan Senior Member Join Date: October 14, 2009 Posts: 141	If you hate trimming cases, trim them once and use a RCBS X-die. It adjusts the length when it resizes the case which is the step that actually causes the case length to increase. I own a couple but have never used them, so all I am quoting here is the advertising. - Ivan.

October 22, 2009, 12:56 AM	#14
joneb Senior Member Join Date: December 10, 2005 Location: Central , OR Posts: 1,888	I trim all my rifle brass. I trim my revolver brass to insure a consistent roll crimp. I rarely trim auto pistol brass.

October 22, 2009, 01:55 AM	#15
Hook686 Senior Member Join Date: May 22, 2005 Location: USA The Great State of California Posts: 2,090	I do not trim revolver magnum brass, as it spaces off the rim. I do check and trim, as needed, rimless brass. My only brass that has really fallen into that catagory has been .30 carbine. __________________ Hook686 When the number of people in institutions reaches 51%, we change sides.