Case trimming

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Peacemaker4

Bearcat
Joined
May 4, 2017
Messages
8
What are your thoughts on trimming rifle cases. Do you always trim? What specs? For example, 303 British, the book says case trim length 2.212; max case length 2.222; max col 3.075. What are you happy trimming the case to? If you trim too much, say 2.209, do you discard the case? How important is this? Thanks in advance.
 

GasGuzzler

Hunter
Joined
Oct 22, 2012
Messages
2,979
Location
Cooke County, Texas
I do when I have a big bunch to process. I might go through and measure them all to get an idea of what my minimum is. Then I trim them all the same and perform all the other prep processes. Then I'm done. I don't check that batch again.

In your case, see how many are within the 2.212-2.222" range. If most are, I'd trim to 2.220" and discard anything shorter than 2.212". I'd keep all the ones 2.12-2.219 as is and trim those 2.220" and longer.
 

contender

Ruger Guru
Joined
Sep 18, 2002
Messages
26,102
Location
Lake Lure NC USA
Bottleneck brass seems to stretch easier & quicker than any other. As such,, for smooth chambering,, trimming is a necessary evil for good handloads.
I study the minimums & maximums for brass. Normally there's about a .010 tolerance between the two. I usually pick the half way point of the .010 as my trim length.
Any brass that is shorter than that,, I load & shoot as my practice ammo. At most,, I may chamfer the inside of the neck to allow easier bullet seating.
Excessively short brass I scrap out. A .003 too short (using your example,) isn't what I'd consider excessive. I'd load it & shoot it.
And I keep brass in groups to avoid the need to trim after every firing.
 

rugerjunkie

Buckeye
Joined
Mar 15, 2005
Messages
1,977
Location
Kansas
Most say to trim to that -.010 from max. I usually go -.005 since I don't see much case growth with what I shoot and am also not one who thinks trimming is that big of a deal. I have several case prep machines that make it a quick task. If you are short by a couple or few thousandths I wouldn't sweat it and use that case. If they are way too short , no need to scrap them. Use them for test loads.
 
Joined
Dec 25, 2007
Messages
10,454
Location
missouri
I think you'll find that factory cases are notoriously uneven. For most needs, cases under max length are fine--it's the grossly overlength ones that cause problems like jamming into the leade and not releasing the bullet as expected.
For those cartridges that require crimping, trimming becomes a bigger issue as case length affects the finished roll crimp. For cases that headspace on the case mouth, length is even more important. That said, I load a lot of 9mm and have never trimmed a 9mm case.YMMV
 

Rich/KY

Bearcat
Joined
Dec 1, 2023
Messages
21
Location
Corbin, KY
Usually trim to the listed trim to length but don't worry if it comes up a little shorter as I don't crimp either cast or jacketed rifle bullets. All my rifles are either single shot or bolt actions, if I had a lever action with a tube magazine that required crimping it would be a different situation.
 

s4s4u

Hunter
Joined
Dec 16, 2006
Messages
2,155
Location
MN, USA
What are your thoughts on trimming rifle cases. Do you always trim? What specs? For example, 303 British, the book says case trim length 2.212; max case length 2.222; max col 3.075. What are you happy trimming the case to? If you trim too much, say 2.209, do you discard the case? How important is this? Thanks in advance.

No, the case will grow back. I trim most of my rifle rounds 5 to 10 thou's shorter than the book trim-to length so I don't have to trim it again next time. This is primarily for ammo I shoot a lot of. It is more important that you size the case properly at the shoulder area, a few thou's short at the mouth is nothing.

I will make a go/no-go "gauge" that is the actual trim-to length and as long as a case passes through it gets loaded.
 

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