Trimming tips?

Ucsdryder

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Jan 23, 2016
Messages
324
How often do you trim?

Do you trim to saami minimum?

How much do you let brass grow before trimming again?

What is your acceptable level of length variation when trimming?

Any other tips or tricks?
 

sedancowboy

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Nov 28, 2014
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Wilsall, MT
I trim new brass to square it up which often means it is a little short of Minimum.
I then check it every time I reload it and only trim if it needs to be trimmed.
Trimming after each firing has not proven to me to have any benefit to accuracy. I have a Sinclair chamber length gauge and measure each rifle and that is what I use for Max length.
Modern design cartridge cases with 30-40 degree shoulders do not grow as fast as old style 20 degree cases.
One trick is to chamfer the inside of the case and only knock the burr off the outside. Do not put a heavy chamfer on the outside of your case neck. That and don't trim any more than necessary and you will have less problems with a carbon ring.
 

Ucsdryder

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Jan 23, 2016
Messages
324
I trim new brass to square it up which often means it is a little short of Minimum.
I then check it every time I reload it and only trim if it needs to be trimmed.
Trimming after each firing has not proven to me to have any benefit to accuracy. I have a Sinclair chamber length gauge and measure each rifle and that is what I use for Max length.
Modern design cartridge cases with 30-40 degree shoulders do not grow as fast as old style 20 degree cases.
One trick is to chamfer the inside of the case and only knock the burr off the outside. Do not put a heavy chamfer on the outside of your case neck. That and don't trim any more than necessary and you will have less problems with a carbon ring.
So what does that mean, anymore than necessary. Are you trimming when you start having accuracy issues? When you have loading issues? Or when it grows .00X”?
 

Eric H

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Aug 15, 2017
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I trim .01 below saami and measure always after cleaning and sizing. I will allow it to grow .003 before another trim and if you use Wilson trimmer you shouldn't have any variation when trimming. Remember to be consistant in cleaning, sizing, trimming, loading and shooting. Also remember to wipe down your brass after sizing to remove the lube used to size.
 

sedancowboy

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Nov 28, 2014
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No No if you wait until you have issues you have waited too long. As Eric said above trim .010 below max case length when you trim. Measure after each reloading cycle. It helps if you reload all cases in a batch of brass and keep the same number of firings on the cases as you go. That way they aren't all over the place length wise.
 

Pdyson

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Nov 25, 2013
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227
Location
Brownwood Texas
I trim to the trim-to-length shown in my reloading manual and I trim every time. It my brass prep ritual. I usually use my FA deprime tool to deprime brass while my barrel cools between strings and I dump it in one of those giant cheese ball jars when I get home. On brass day I first anneal all the brass. Then a quick 10-15 min clean in the wet tumble or ultra sonic. Then I resize, mandrel expand, trim, chamfer, debur. Then a quick 2nd wash to remove the die wax and graphite dry neck lube. 20 mins in the jerky dehydrator. Prime and neck brush. Ready to load. I try to be consistent and eliminate variations that could affect group size. So I do the exact same process every time…regardless of the rifle cartridges. My pistol ammo isn’t treated so well mainly because I can’t shoot it accurately enough to see a difference.
 

QuietTexan

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Nov 16, 2020
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712
Location
Texas
How often do you trim?
When the case is about to the end of the chamber. Or if they're really, really off when new.

Do you trim to saami minimum?
Nope, just back a little bit.

How much do you let brass grow before trimming again?
Until it gets to the end again. Some cases never need it again before something else goes (primer pocket).

What is your acceptable level of length variation when trimming?
0.001" or better. Any decent system including automated/powered drive models can hit that spec.

Any other tips or tricks?
Buy a bore scope and look at the actual length of a fired case in your chamber instead of trimming to an arbitrary spec.

It really seems like the length and chamfer/deburr doesn't vary much if you minimally size cases and have a matched set to start with. I use a VLD chamfer tool in an LE Wilson trimmer and unless I abuse the brass by dropping it on concrete it comes out of the gun remarkably similar to how it goes it.
 

QuietTexan

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Nov 16, 2020
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Texas
Since I got my Teslong borescope I take a piece of sized brass and chamber it. Then I insert the scope and see how much gap between the end of the chamber and end of the brass. I found out I have been trimming when I didn't need to. You can also get a chamber length gauge.
100% agree.

Trimming is something like Item #47 on the list of things to worry about in my book. IMO cleaning method and lube makes a bigger difference than trim length.
 

misterc01

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Feb 15, 2019
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680
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Florida Panhandle
I start new brass at SAAMI min. From there, I do not trim until it reaches MFR trim length, then I trim back to half way between the two. Example: .308 Max is 2.015. Min is 2.005. So: new to 2.005, then at 2.015 I trim back to 2.010. and so on. So, far works for me.
 

Jeffrey Van Zandt

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Feb 26, 2013
Messages
524
Location
tok
How often do you trim?

Do you trim to saami minimum?

How much do you let brass grow before trimming again?

What is your acceptable level of length variation when trimming?

Any other tips or tricks?
I match prep all my long range brass and trim every shot anneal also every shot for time to I use a sinclair gauge to get the OAL of neck then set my trimmer back two tho from that point pic or case insert gauge from sinclair
 

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Mike Matteson

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Jun 26, 2017
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I use a Henderson Precision Tri Trim Gen 3 Case Trimmer. I set up for each different caliber I shoot or sons rifles. I change out cutter heads and rod as needed to caliber, and chamber I load for. So I chuck up each case after each firing to cut to length. I also anneal each time now. [email protected] It just one more step in reloading.
 

lyle2231

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Jan 26, 2014
Messages
219
Location
Hollywood
How often do you trim?

Do you trim to saami minimum?

How much do you let brass grow before trimming again?

What is your acceptable level of length variation when trimming?

Any other tips or tricks?
I use a Giraud trimmer at every reload
I shoot .223 mostly. AR15.
 
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