Case Trimming: How Often?

There are some great responses above, I will add there are some, my plinking ammo, calibers that I trim once and done. By the time they grow big enough to trim again they will be in the recycle bin.
Note - they are neither hunting or precision loads, they are go out and shoot steel and punch paper for fun or to train.

I load in groups of 20 cases at a time. For length, I run them thru my caliper quickly and cull out those that are over SAMMI regs. I try to keep them .005 inches below that measurement.

Find out your chamber length and then you can decide when to trim. Reamer prints are helpful if you had a gunsmith chamber the rifle. Agree with Mikecr measure the end of the chamber:

Every time for rifle cases. Henderson trimmer changed my life, I can do hundreds of cases an hour with a very high level of consistency.

As many others have said, I trim after every firing, if nothing else at least for consistency purposes.

I also trim on the Henderson trimmer each time. I'm not doing so much for the length but to give it the chamfer.

I trim when the length gets to max. In my case (no pun intended) a .308 and .015. I then trim back to .010. I am currently using a WIlson Trimmer, but prior to that, I used an RCBS and never had a problem with it. When the cutter started getting a little dull, but still doing the job, I contacted RCBS about buying a new one, and they replaced it at no charge. Contact them I am sure they can address any questions or concerns.

General RE LEE said:

I am getting into reloading and all my brass is once fired. I had a RCBS Manual case trimmer I bought from Midway and it was an absolute piece of garbage. Broke first time using it.

After how many rounds do you have to trim cases? Hopefully I can get a decent case trimmer by the time primers come available and I am abe to shoot.

Click to expand...

RCBS will make it good, but I also use the Little Crow, have one for each caliber, that way its a grab and trim, no changing for different calibers. A little pricey but well worth it.

I trim when the brass gets out of spec. Some cartridges or brass stretches fast, within 2-3 loadins. Others can go a bit more before needing trim. And some AI users say they never need to trim. So it will vary with the cartridge, quality or brass, quality of lube, and your technique in sizing. i will say the Lee Mandrel type expander cut down on brass stretch, but I rarely take the time to set up the extra step anymore.

I trim when needed ,but I measure after every firing , I also use the Forster Datum Dial kit. Been using the same Wilson case trimmer for over 50 years. I'm lucky Wilson's is located 15 Min. drive from my house.

I have a manual RCBS trimmer I've used for over 30yrs.the only thing I don't like is I can't seem to get consistent lengths! And now I can't find a collet to fit my latest loading adventure the 6mm ARC!

Sinclair Chamber Length Gauges are your friend. "book" numbers, don't mean anything, your actual chamber does!

I have a Lyman, Gracey and a new Frankford Arsenal "Platinum"
All work good.

I was lucky and was able to score 4 complete Forster case trimmers at a flea market. I keep all four set up to the max case length of my 4 favorite calibers, 30-06, .270win, .243win and .308. I follow the same steps on all my brass. I try to load all the same makers brass. When I can score a bunch where I know they are all from same or close mfr dates then I buy a thousand. Whether it is new, once fired, twice fired whatever. I clean all the cases in a vibratory cleaner, I full length size them all, I run every one through the case trimmer, if it needs it it will be trimmed, if not, no harm no foul. I chamfer inside and out of all case necks, I measure the case neck thickness of each case, trim thickness if it needs it, I prime, charge, seat bullets, then drop the finished round into a SAAMI block https://www.lymanproducts.com/ammo-checkers-multiple-blocks if it fits the block perfectly it goes into my "shootable" inventory, if not I pull the bullet immediately and put that case into a coffee can that I call "needs investigation". I also check concentricity runout on 1 out of every 10 rounds. Only ever found 1 round fail that check. Yes this chews up extra time, but perfection is why I reload in the first place. I figure I'm not doing myself any favors by taking a short-cut. Do you have to be this anal about it, of course not. I am really happy with my shot to shot performance.