Thread: Do you always need to case trim?

I trim every firing. I neck turn my cases before the first firing and use Redding bushing dies to get consistent neck tension and low ES. If the cases are not all exactly the same neck length there will be variety between cases, so I trim to just over book max length. Yes, the difference from one case to another is tiny, but it's all about eliminating tiny differences and they all add up. My last load of .300 WM reloads had an ES of 4fps over 5 shots.

I also think it's important to use a good trimmer that supports the case well. I use an LE Wilson jobby.

I haven't yet trimmed.
I've Norma 223 cases that are on their 7th load and Lapua Palma 308 cases on their 6th load without trimming (or annealing).
223 cases have only been neck sized. 308 cases have been neck sized and full length sized.

I would trim all cases after first firing just enough to get them all the same length and possibly cull any very short cases.....eg FC brass.

Overall case length and how that relates to the chambers maximum length depends on the reamer used in that rifle and is nothing to do with headspace or jump to lands.

I personally would mark brass and size for each rifle as required.

If brass is to be used in two different rifles with the same load then basicly you are going to have to size and trim for the tightest chamber which WILL stretch your brass in the looser one and cause these cases to grow lengthwise and if the difference is more than a little case head separation is inevitable.

I use Sinclair chamber length gauges, have for over thirty years. They're inexpensive and give an accurate reading. You'll need calipers though.

https://www.youtube.com/watch?v=JKnXJxaAw2U

Originally Posted by 10-Ring

I use Sinclair chamber length gauges, have for over thirty years. They're inexpensive and give an accurate reading. You'll need calipers though.

https://www.youtube.com/watch?v=JKnXJxaAw2U

+1 Ditto, and the reamer drawings. Have 5 of them. Made the last one myself out of brass though rather than go to Sinclairs - I had nothing else I wanted off them at the time and the shipping would have been shit.