I have just started reloading with a new 550B and with both 9mm and 45 loads, I have a problem keeping the OAL variation small and consistent. When I run a single case through the machine, the OAL of the 9mm FMJ RN comes out to be 1.150 +/-0.003. When I have a case in each stage, the OAL will often be 1.175, with a lot of variability on the increase in length. If I run the longer cartridges through one at a time with no adjustments to the machine, they will almost always come out sized properly at 1.150 +/-0.003. The same variation in OAL variation happens with the 45ACP with cast SWC so it is not specific to the 9mm or 45ACP cartridge.
Is this variation in OAL an inherent feature of the 550B that when depriming and resizing the OAL operation becomes a bit longer because the machine is bending somehow resulting in inconsistent OAL? Or is this a setup issue or specific problem with my 550B, and if so, what should I look for in correcting the problem?