Case trimming

[Peacemaker4]

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]

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.

 

[Durango Dave]

I don't measure all my rifle brass. I use my trimmer to "measure" the cartridges.
By that I mean I set the trimmer to the trim length (2.212 in this case)
Then I put each brass in the trimmer and trim to that.

 

[contender]

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]

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.

 

[Mobuck]

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]

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]

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.

 

[DBnoise]

What matters is keeping your chamber clean also. You have to do some analyzing. I try my very best to "move" my brass as little as possible. Meaure after fireing/lubed/before sizing, then after sizing and try to move my brass .002 in case length, shoulder case/neck junction and the neck just enough to give me .003 neck tension on the bullet. Adjusting my dies according or using a different die. Not all dies ate the same. Some of my hot loads will grow .003 inches. I trim normally. 010 below max for first load and trim when they get to .003 to .001 below max case length. If am doing accuracy shooting, they are all trimmed at the same length .005 below max case length. I do have a bore scope and check the gap at the end of the case mouth to throat. There are some variations my rifles where the chamber neck is cut a little longer than max case length but have not run across one shorter than the max case length. I also found it doesn't stretch much in firing but more in the sizing I process with total spray. That is why if I want to shoot to most the accurate capability I will neck size or use a roll pad to lube then size the case. In that process I wipe the inside of the neck also very lightly.
Your 303 depends on what you are shooting it for. I doubt it would be high volume. So just a spray, size it, trim it needed, clean em, load and shoot.

 

[Bigbore5]

I even trim my pistol brass