[robocop10mm]

Roll crimps, especially heavy roll crimps are length sensitive. The odd long case will buckle when the die is set for a shorter case. If I need to apply a heavy roll crimp, I try to do one at a time so I can "feel" the case in the die.

When they buckle, they will end up shorter. You can fix the buckled rounds by running the loaded round into a sizing die w/the de-cap stem removed.

[spittinfire]

Would you be nervous to shoot a round that is .015" shorter then what the load data calls for? It's a starting load but still, thats a lot of lost space.
I did notice that at the called for OAL, the top of the case was not into the cannalure at all.
I'm going to try a few other cases and see what happens. They may end up going into 38 loads but really wanted to play with a light 357 bullet.

[DMC]

"I was flaring the mouth slightly more then I do normally "

Maybe try less flair. Could be catching? Or pot a light taper crimp, then the roll crimp. Not that that's necessarily the way to do it, but it would eliminate the excessive flair before the final crimp.

DC

[robocop10mm]

The degree of flare will vary with case length. The occasional long case will give you extra trouble. It will overly flare and will overly crimp. This can lead to very bad results.

[spittinfire]

I was always told straight wall cases won't stretch and these all measured the same.

[Shade]

Originally Posted by spittinfire

I was always told straight wall cases won't stretch.

BZZZZZZZZZZZZ goes the BS meter....

Straight walls grow but not as fast or as much as bottle necked cases.

I do not have time to discuss the details right now, will later.

But you solution is the Lee Factory crimp die. I will explain later also.

The short answers is slight variation if case length, unless you trimmed
them all they will vary by a few thou. Taper crimps are very sensitive to
case length. The Lee Factory crimp die is not.

[spittinfire]

Originally Posted by Shade

BZZZZZZZZZZZZ goes the BS meter....

Straight walls grow but not as fast or as much as bottle necked cases.

I do not have time to discuss the details right now, will later.

But you solution is the Lee Factory crimp die. I will explain later also.

The short answers is slight variation if case length, unless you trimmed
them all they will vary by a few thou. Taper crimps are very sensitive to
case length. The Lee Factory crimp die is not.

I was using a Lee crimp die.

[Shade]

Originally Posted by spittinfire

I was using a Lee crimp die.

Hmmmmf, gonna have to think on this one some more...

I am on the road this week so lotsa dead time in hotels.

[Kestral]

Just started on a mixed bag of 38 s/w reloads,the cases are Norma.Kynock, Dominion & Gevolet. They all reloaded very well except for the Gevolet,they all had very pronounced bulges about a third of the way down,using exactly the same bullets and powder,and also sized to the exact same dimensions.Your original problem with your bulged cases,could have been caused by a batch of thinner walled cases, which I am blaming for my results.

[Innovative]

The Lee Factory crimp die is the best crimping die available for SOME "thin necked" rifle cases that require a crimp (not many). The 30-30 is a good example.

However, I prefer to use an ordinary roll crimp die on the .357 Mag. Just be sure to not over-do the crimp. I suspect that's your problem, and it's a common handloading problem with .38 Spec. or .357 Mag. loads.