Coke-bottle shaped 9mm?

Jonesyatpl

Jonesyatpl

CGN frequent flyer
Rating - 100%
476   0   0
Location
Nanoose Bay, BC
Total newb question....

Setting up the dies, I seem to end up with a correct cartridge OAL, Taper crimp at the mouth is in spec. Case gauge gives it a thumbs up.

However, after all four stages are complete, My 9mm looks like (slight exaggeration) a coke bottle. Definitely no setback will occur, as it slims down about 7 thou after the bullet. cartridge base is still fine, every other measurement seems to check, just never seen it before. Noticeable by the naked eye.

I checked some US sites, they seem to have seen it as well, and dismiss it as no biggie. Any thoughts on whether this is an issue?

Dillon 550, carbide dies.
 
You are over resizing the case and reducing the case diameter smaller than a new case at minimum dimensions. Meaning you are pushing the case too far into the die, so adjust the die upward until it is not over resizing the case. You only need to reduce the case diameter .001 or .002 smaller than the expander diameter and not over work the brass.
 
the 9mm is a tapered round, but the Dillon die resizes it parallel. When you flare the case, seat and crimp a projectile, you will end up with a slight coke bottle shape. Has worked fine for me in 20k+ rounds reloaded on my Dillon XL650 with Dillon carbide dies. I recently switched to Lee factory crimp dies to reload for my S&W 929, and they do a proper taper resize and a taper crimp. You can see the difference in the reloaded rounds below. Dillon on the top, Lee on the bottom.

View attachment 49698
 
Thanks, Van Man!

The top one is exactly what I am consistently getting shape-wise. All the other forums (AR-15 dot com, etc) seem to have the same conclusion. Looks like a lee FC die will go on the list. But for now, it's nice to know I won't have to pull any bullets. First night on the press. Steep learning curve!

Jonesy
 
Glad to pass on something I've learned from these forums :). The resize is only a cosmetic difference. Two seasons of practices and IPSC qualifiers using the Dillon dies with no problems at all. I only switched one of my tool heads over to Lee FC dies because I wanted the stronger crimp for my S&W 929. I had heard that you need a good strong crimp to prevent the projectile backing out from the pounding the un-fired rounds get in the cylinder. The Lee FC dies are supposed to give a good strong crimp without undersizeing the projectile which is a bad thing.

Jonesyatpl said:
Thanks, Van Man!

The top one is exactly what I am consistently getting shape-wise. All the other forums (AR-15 dot com, etc) seem to have the same conclusion. Looks like a lee FC die will go on the list. But for now, it's nice to know I won't have to pull any bullets. First night on the press. Steep learning curve!

Jonesy
Click to expand...
 
I use an undersize Lee die with all my 9mm. Works great and gives me the same result but only with certain cases. WIN cases will give me a slight bulge. Otherwise, all the Federal brands (FC, Speer, CCI) will not but if I use my Hornady re-sizing die I will get set back. Seeing that bulge offers me a certain comfort knowing there is not going to be any set back.
 
Carbide dies typically have only a narrow ring insert to do the sizing. This is why tapered 9mm cases come out of the die with a parallel section at the mouth and a more sharply tapered base. Duplicating the shape of a factory 9mm case would require a much more expensive die without any functional advantage.
 
I have Lee, Hornady and RCBS 9mm carbide dies and the carbide ring in all three dies are tapered and almost as long as the 9mm case.
And as VanMan stated above you will have much better results with the Lee four die set which will eliminate the Coke bottle shape.

My 1973 RCBS .357 carbide die did the same thing and it had a narrower carbide band in the die. And you still should be able to reduce the Coke bottle effect by not sizing down the case as far.

"BUT" we live in a plus and minus manufacturing world and no two chambers and dies are the same. And a large diameter chamber forces you to size further down the case. But it seems the newer carbide dies are being made better with tapered carbide inserts.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom