Overall Bullet Length 9mm

X

xman111

BANNED
Regular
BANNED
Rating - 100%
20   0   0
Location
British Columbia
Hey guys, new to reloading. Just trying to set up my LNL AP press and the bullet seating die and trying to figure out the overall length. Can i measure my final round to a factory round that i know works good in my gun? Does it matter if im using 124gr bullets, and measuring it to a factory round based on 115gr bullet? At what point is it insignificant, a couple thousands of an inch?

Just trying to get my head around it all.
 
just a few pointers:
- the 124gr bullets are usually longer than 115gr ones which means at the same COAL them 124s seat deeper in the case.
- use the COAL from the manual. Unless specified otherwise, the bullets in the manual are round nose.
- 9mm is a high pressure round and a couple of thousands deeper may generate excessive pressure.
- seat the bullets rather long than short as long as they fit in the magazine and chamber ok
- if your bullet is different from the one in the book but the same weight, make sure it seats equally deep (or less).
- read the manual twice before even starting
 
Don't go to the minimum OAL if you don't have to. What is your 115grn round OAL?

All you need to do to know if the round will chamber is take your barrel out and try it. It should drop in freely and should just fall out when you turn it over. Start off making some rounds with no primer or powder in between the max and min OAL for your bullet weight and go from there.
 
hey looking again at my cartridges, i have 124gr factory ammo. I just put one in the calipers and it measures 1.155", and it fires great in my gun. Would i be safe just making my rounds 1.155" as well?
 
xman111 said:
hey looking again at my cartridges, i have 124gr factory ammo. I just put one in the calipers and it measures 1.155", and it fires great in my gun. Would i be safe just making my rounds 1.155" as well?
Click to expand...

Not necessarily. It depends on the profile of the bullets you'll be loading, as this determines where the ogive contacts the lands, which in turn affects the seating depth.
What kind of 9mm do you have? Some have a shorter chamber than others.
 
Use the barrel of your pistol to gauge correct OAL. Make a dummy round and adjust the seating depth until it drops all the way into the chamber just as easily as a empty sized case. Save your dummy round to allow for quick setup of your seating die in case you ever use different bullet types.

Using a round of factory ammo would be a good starting point to set up your seating die, but you still have to make sure that your reloads will chamber freely at the OAL set by the factory round, as bullet shapes will vary.

This approach will save you a lot of hassle compared to chasing a number out of a manual.
 
Tjhaile's comments are how I'd do it. You can certainly start by measuring ammo that you already know worked for you but it's still a good idea with each new batch of bullets that are of a different shape from previous ones to do a single dummy round and chamber check it as he suggested.

I know that my Beretta isn't fussy at all within reason but my CZ's don't take kindly to COAL's that are too long. In the case of my CZ's depending on the bullet shape I need to go anywhere from 1.10 down to 1.07 or it jams up on the rifling lands.

And because this means there's less case volume I found that I had to load to slightly under the max powder spec as the reduction in case volume due to seating deeper produces a higher peak pressure. So I started on the low side and chrono'ed samples and worked up to my desired 130 power factor. This ensured that I didn't produce loads with a peak pressure that was too high. I found that differences of even .010 in seating depth produced changes of around 15 to 20 fps in the velocity for the same powder load.

This is why most reloading how-to's will suggest starting at lower powder measures and work up when dealing with a new powder and new bullet type. And why you want to keep good notes so you can go back and use previous recipes without the need to go through this testing each time if you don't need to.
 
You must log in or register to reply here.
Back
Top Bottom