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COL variation on 9mm
- Thread Starter howardm4
- Start date
Member 34319
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I've found that the better the bullet, the less amount of COL variable.
FMJs being the most consistent bullets, but also the more expensive reload option.
Most cast and coated bullets get a final swage post coating (copper via electrolysis or polymer etc). That final swage to ensure proper bullet diameter usually leads to greater variables in bullet length, leading to COL differences.
COL sort of matters but as long as headspace is fine, IE the bullet isn't too far out to interact with the throat and interrupt headspace on the case, I don't see it as an issue.
FMJs being the most consistent bullets, but also the more expensive reload option.
Most cast and coated bullets get a final swage post coating (copper via electrolysis or polymer etc). That final swage to ensure proper bullet diameter usually leads to greater variables in bullet length, leading to COL differences.
COL sort of matters but as long as headspace is fine, IE the bullet isn't too far out to interact with the throat and interrupt headspace on the case, I don't see it as an issue.
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Purchase a case gauge, if you run your rounds and they slide in and out of the case gauge you will not encounter any issues. I have reloaded thousands of rounds on my 750. All range brass cleaned and resized before running through my 750. I check about one in every 20 just for my own peace of mind. The more you use your machine the better you will (feel) small issues. Great machine!!
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- Thread Starter
- #4
Yes, they all gauge well w/ no issues
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On my 550c I will run 1 bullet through all stages and ensure setup is correct. This is my starting point and I always make fine tune adjustments from here.
When you get cases hitting dies in all four or more stations you may find that your tool-head moves up & down slightly - mine does.
After die setup with a single round, I normally need to drop my seater plug .002/.003 knowing that the tool-head will move slightly when all stations are in use. After that single adjustment I'm usually within .003 on my OAL (round to round) for the rest of the session.
I would also prefer to be over the book OAL vs under.
When you get down to your last few rounds, continue to populate station 1 on your press with brass. This will help keep the last few rounds seating at the right depth.
When you get cases hitting dies in all four or more stations you may find that your tool-head moves up & down slightly - mine does.
After die setup with a single round, I normally need to drop my seater plug .002/.003 knowing that the tool-head will move slightly when all stations are in use. After that single adjustment I'm usually within .003 on my OAL (round to round) for the rest of the session.
I would also prefer to be over the book OAL vs under.
When you get down to your last few rounds, continue to populate station 1 on your press with brass. This will help keep the last few rounds seating at the right depth.
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Personally, .002 would be good with me. I understand 9mm can spike pressure faster than some other rounds but this seems to be within normal variation for me (I use a 750 and a Rock Chucker single stage).
