Hi

I am in the midst of reloading some .357 Magnum for the first time in at least 10 years. (Though I've been reloading for 25 years or so.) Not going so well.

I do not usually trim pistol cases but maybe I should have in this situation. Using the RCBS directions for roll crimp very carefully I have set the die for proper coal and then a reasonable crimp on the first case. But then the degree of crimp varies from barely discernable to overdone or even a crushed case on succeding cartridges. Some cases are not obviously crushed but are distorted just enough that they will still not chamber smoothly in my Mod 66. My guess is that this is because the cases are not all the same length to begin with and this makes the crimp different on each one. No big loss this time even if I toss the whole batch because there are only about 20 cases in the batch. And they are of mixed manufacture.

Looking for second opinions and advice please.

Of course, before I do any more, I will readjust the sizing die from scratch just in case part of the problem is there.

Thanks in advance.

Steve - (snowbound in NW Missouri)

Are you seating and crimping at the same time? If so that may be your problem. Seat the bullets in one operation and crimp with a second operation. Also you may expereince differences in crimp depth depending on the brand of case and OAL.
Personally I never trim straight walled pistol cases. The mouths start to fray after multiple reloads and I toss them into the scrap heap.

Been there, done that! You have figured out the problem already, in that there is quite a degree of difference in case lengths, especially if your brass comes from different brands. Here are your options:

1.Trim all your cases to the same length. Straight-wall revolver brass doesn't usually "grow" much, unlike bottleneck rifle brass, unless you load to really high pressures, and even then, you won't need to re-trim often.

2. Sort your brass into lengths, keeping everything in a batch within +/- .001", to minimize crimping disparity. Obviously, you'll have to readjust your crimp die for each batch.

3. Try a Lee Factory Crimp die or a conventional taper crimp die, either of which is much less influenced by differences in case length than is a roll crimp.

Being the lazy sort, I chose Option #3, and the Factory Crimp Die has worked well for me.

I have been reloading 38's and 357 for years. I never sort by brands for plinking loads. Trim all your cases to spec. length and load them. For serious hunting loads I may sort a few cases for condition. If your using a 3 die set adjust seating and crimping on a dummy load . Set the overall length first, back of the seater and set desired crimp. Then screw seater down to contac bullet. This should give you a good cartridge. You then may have to make a minor adjustment now and then.
I have never had to trim straight wall cases the second time. I'm not at my reloading bench and are typing this my memory as best as I can.
Trial and error and practice. Nickel cases can be a different story. Cracks
will appear more often ,you wont get the life of brass cases. good luck
and always check powder level before seating bullets.

case length must be the same when seating and crimping are done with one stroke of the press. i never use mixed brass and rarely have a problem. i measure every fourth or fifth case after several loads at magnum velocity looking for stretched cases. when they become more frequent i toss the entire batch out.