Opinion on 9mm length issue

[Wanted]

I was running some 9mm 124gr FMJ from Precision Delta. I have the col set as 1.124. They are running 1.124 to 1.130. I have never had an issue like this and I don't trim pistol brass.

[CeeZer]

OAL/COL has nothing to do with trimming or not trimming brass in 9mm caliber. Trimming 9mm, .40s&w and .45acp brass is waste of time, it's not needed, not even recommended as it's unnecessary. Most brass with str8 wall need no trimming!!

Your sitting die has most to do with it as well as uniformity of bullets.

- If you seat bullets with flat seating stem that pushes at the nose of the bullet - you'll get most accurate and consistent OAL. Wadcutters or similarly designed bullets that have flap point will benefit from that stem.

- If you use seating die stem that seats bullets pushing on ogive - you'll get most consistent round chambering. OAL will vary slightly and velocity may not be as consistent as case volume below bullet will vary some thus causing variations in pressure from round to round.

In case you load on a progressive press, shellplate and variations in downward pressure at different stations will give inconsistencies with OAL regardless of seating stem in use due to flex in whole system.

Edited January 23, 2011 by CeeZer

[G-ManBart]

I was running some 9mm 124gr FMJ from Precision Delta. I have the col set as 1.124. They are running 1.124 to 1.130. I have never had an issue like this and I don't trim pistol brass.

Lots of threads on this...one where I linked many of them is here:

http://www.brianenos.com/forums/index.php?showtopic=121444&view=findpost&p=1372895

No two bullets are the same, and the press will seat them differently when all stations are full versus some empty.

[Wanted]

Looks fairly common. Thank you. Can you help with searches? Is there a trick to finding a specific issue? For instance on this one I'll put- Differences in col. I'll get a lot of threads on load data or something unrelated.

[rhyrlik]

So what is your question specifically?

[Wanted]

Would the difference in col caused by various case lengths, affect pressure and safety. I guess is what concerns me most.

[twodownzero]

Minor differences in length will have no significant difference on the performance of your ammunition.

[Wanted]

Thank you, everyone here is always helpful. I appreciate it.

[G-ManBart]

Looks fairly common. Thank you. Can you help with searches? Is there a trick to finding a specific issue? For instance on this one I'll put- Differences in col. I'll get a lot of threads on load data or something unrelated.

Yep...very common. A couple of thousandths either way won't cause any problems for what we do...for 1,000yd rifle ammo, maybe it's worth worrying about.

There are a couple of ways to search. I usually go to the section where I think I'll find the answer, then use the search box on the upper right. Keep in mind, on basic issues like OAL, sometimes they're in the beginners section rather than the specific reloading section. I'll normally start off with a term like "OAL" and see what happens. If that's too many, I'll add another term and make it something like "OAL variation"...just play around with a couple of combinations and see what comes up. Using just that idea you'll find 95%+ of what you're looking for. Sometimes you have to go into the advanced search, but not too often....you'll have to just try that a bit to see how it works. R,

[Wanted]

Thanks again.

[njl]

Would the difference in col caused by various case lengths, affect pressure and safety. I guess is what concerns me most.

The difference in COL isn't actually caused by case length variation. It wouldn't be unless you had some weird sort of press that seated relative to the case mouth.