9mm coke bottle shape but case is undersized

[Charlotte the flyer]

My last (first and only so far) 9mm batch bulged out at the top of the case where the boolit seated into it. I thought that I'd need more crimp to get rid of it but I've just measured and I'm already under the SAMMI case diameter value of .380in. (.378 ish I think it was). Presumably this means that I need less crimp but won't that make the coke bottle effect worse, can anyone clarify?

I just followed the Lee instructions on how to setup the seater die not really understanding the implications of correct neck tension / diameter. The tester bullets dropped into the rifle nicely so I know that the brass was roughly the right diameter.

NB, when I fired them I could actually see the projectile go down range with 3.6gn of Titegroup (starting load in the Lee manual). I'm going to try a higher charge but I want to get this neck issue sorted and fully understood first.

I'm using a Lee 3 die set : resize, expand then seat/crimp in one.

[Sim G]

Far too much taper crimp going on. Wind everything back and start again.

I've always found starting loads to be pretty much hopeless. Start at the middle of that data. (3 minimum, 5 maximum, start at 4...)

[tackb]

my glock ammo used to look a little 'waisted' but always worked fine ?

could you pop a picture up to show us what you mean ?

[NoEntry]

When I used Lee sizing dies on my 9mm I got the same effect. I think the f/l sizer makes he cases a Little small.

I now use Lyman dies and don't have the same issue.

It didn't seem to cause any issues with accuracy though, they just looked a little strange.

Mike

[toffe wrapper]

The coke bottle shape is common on 9mm reloads.

Set you size and de priming die fully in so it touches the shell plate

Set the expander die so it just flares the case enough to allow the bullet to sit on case

Set the seating and crimp die to just remove the flare and seat bullet to required length.

Make a couple of drill rounds and test in the rifle. Allow the bolt to slam and fully close on the drill rounds a few times and check bullet is not coming out of case. increase crimp a little if it does. Also check the bullet is not touching the rifling, colour the tip with marker pen and check for marks. The shape of some of the 9mm bullets on the UK market means you may have to load them a little shorter than the books say. I have some plated 124 grain bullets that when loaded to book length touch the rifling. 9mm rounds should fall free from the chamber with no help.

I reload for my 9mm LRR and tested various crimps on drill rounds before adding primers and powder. Not enough and the bolt slamming forward can move the bullet out of the case like using kinetic hammer which will jam it in the rifling and cause over pressure. Pulling the bolt open ejected the case leaving a bullet in the chamber just catching the rifling.

TW

[Dark Skies]

Are crimps necessary? I don't use them on any of my military rifle rounds - nor on the pistol rounds fired through my under lever rifles.
I've never had an issue and it makes things less likely to go pear-shaped when pressing new rounds.

[toffe wrapper]

Yes crimp is necessary on my 9mm LRR the bolt slamming forward could case the bullet to move forward or even be pushed back into case.
This can then cause pressure issues.

TW

[Sim G]

nor on the pistol rounds fired through my under lever rifles.

Then you should do....

[phaedra1106]

As Sim G says, underlever rifle rounds should always be crimped and preferably flat pointed!.

[Daryll]

...nor on the pistol rounds fired through my under lever rifles..

To be honest, you've been lucky not to have had problems.....

A few years I go I went down to Phoenix with some ammo I'd hurredly made the night before. I didn't have any clean brass, so used some nickle cases I had sitting around.

I started shooting T&P1, then found I was having trouble loading the rounds, and on inspection the bullets had been pushed back into the cases so the cases weren't feeding into the chamber.

Of course the nickle cases are thinner than brass, so the crimp die wasn't crimping and the bullets were being pushed back into the cases by the spring pressure in the mag tube.

(When I got home I pulled all remaining bullets from that batch and binned every nickle case I had...)

Back to the OP...when i was loading 9mm for my Browning and Glock, I also had some funny shaped rounds, but they all went bang and went in the right direction...!!
One problem with reloading 9mm is that the case should be tapered... something tricky to do with carbide sizing dies. I was advised to go with non-carbide sizing dies to get the right shape, but the faff of cleaning, lubing, sizing, then cleaning again put me off.... I made do with coke bottle shaped rounds..

Daryll