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+--- Thread: 6.5 grendel to 6mm arc (/showthread.php?tid=764)
6.5 grendel to 6mm arc - herman lesley - 09-18-2022
When necking down 6.5 Grendel to 6mm ARC, do you trim the case before necking down or after?
RE: 6.5 grendel to 6mm arc - Dino11 - 09-18-2022
If your die will size the case with the decaping pin removed and not crush the shoulder then size it before you trim. If you size it and the shoulder crushes then trim .020 from them and size, measure and trim to length.
Having done a bunch of Grendel brass to 6 ARC anneal the cases before you size them, it will go a lot smoother and you will get more consistent cases.
Don't just measure the OAL... Check the CBTO to make sure you are good to go before the final trim. Use a fired non sized case to get your correct shoulder bump. only bump the shoulder .002 to .003 from the fired case CBTO. Your brass will live a long life as long as you only use moderate loads. I have had cases that have been loaded 14 times before retiring them.
RE: 6.5 grendel to 6mm arc - CZ527 Guy - 09-18-2022
. Suppose this may depend on whose dies you are using. I have trimmed the majority of my reformed Grendel brass after necking down. Then I am using Whidden bushing die or the Mighty armory full length sizing die.
As I recall I had similar issues when sizing 17 fireball. in that case the brass had been annealed prior to forming. when I broke away from annealing B4 initial forming the crushed cases went away. I know this is contrary to Dinno suggestion above. Something to experiment with I suppose.
RE: 6.5 grendel to 6mm arc - Thelaststraw - 09-22-2022
I always trim after sizing since not all brass is the exact length factory....yes, even Lapua in my experience. I just recently did 200 Lapua cases from same lot and the difference taken off the min to max was surprisingly large. If I trimmed before sizing, my necks would be all different lengths after sizing.
RE: 6.5 grendel to 6mm arc - Dino11 - 09-23-2022
Some dies will not size the cases unless they are trimmed a little. You do not need to trim them to size before running them through the die, but take .015 to .020 off them then convert them then size to length. If you take off .020 before hand you should only need to remove an additional .010 to .015.
RE: 6.5 grendel to 6mm arc - GRH - 09-23-2022
Never had to trim first.
I bought some PPU in desperation that has not been used and it went fine as is. I have a batch of 100 Starline (dwindling) that I've been using all summer and they formed fine without trimming first also.
I now have a fresh batch of 200 Starline and the only thing I did different was to anneal them first, because for whatever reason the shoulders on my first batch got very hard, which I noticed during processing after the first firing.
IDK why, just happened.