I need some advice from the reloading experts. I have started reloading 357sig on a Dillon 550B and getting vaired COL of up to 11,000. I have set the COL to 1.140 and get vairiations of between 1.147 and 1.136 and cannot ID the problem. Could anyone tell me a possible cause for this??

Hey Squiz,

Are you SURE you're not "short stroking" the ram of your dillon? That can cause that. Also who's dies are you using and are you certain they are adjusted properly? Check the manufacturers instructions on how to adjust seating die and then check Dillon's instructions, sometimes they can vary a bit and you'll have to make an educated guess -- and are you seating bullet and crimping in the same station or do you use a separate crimp die? I'm not familiar with .357 Sig but load a ton of 45acp, 38spl, and 357 on my RL550B and haven't run into that.

You can also write Dillon tech support, they are VERY good about getting back to you within 24 hours with any issues and have been a big help to me.

Art

.005" to .010" is normal. Some use Uniquetek's toolhead clamps. General info > There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

quote:

Originally posted by 243winxb:
.005" to .010" is normal.

it may be normal, but its NOT acceptable .. .01k short is WHAT giant increase in pressure?

I don't know the 550B but own a XL650 and I believe this problem is common to both.

I'll second 243winxb and will add one grossly underrated possible cause : shellplate looseness allowing unwanted vertical sloppyness of dito. When tightening the shellplate, aim for smooth rotation but no more.

Shell Plate - Yes that can be a problem also if the flrs die is touching it. The 357 sig with RCBS dies is the same as a bottle neck rifle when sizing. Make sure each station of the shell plate is the same measurement. They should measure about .125" +.005" Measure Shell plate