Decided to give my new redding body only sizing die a try to reload some 300wsm. First put the die in my wet vibritory cleaner for 20 minuets, then wiped off using action cleaner. Unfortunately lost the set up directions the redding BOSD came with. Absolutely scoured the redding sight for info but found none. So I simply began by setting it up similarly to my Redding FL sizing die directions in that touched th die to the shell holder and backed off one full turn and lowered and sized in 1/8 or 1/4 increments . First I measured a 1x fired case with my Hornady size .420" head space gauge, (did confirm I'm using the correct type E #420 bushing) lubed with One Shot and resized the case measured it saw it didn't bump back the shoulder at all which quite surprised me as the resizing stroke took noticeable effort, also I could see the entire surface of brass showing evidence of being worked by the die save for about the last 1/4" of brass near the base. I lowered the die in 1/8 turn increments sized and measured.
Did this three times with three different pieces of the same lot# 1x fired brass and the headspace measurement remained unchanged or actually grew on all three.
The force required to resize the brass increased every time until I finally stopped after 3 tries when the force required to cam over the press became in my experience much to great and I feared I would either get a case stuck or ruin the die. The cases well very very well lubed with One Shot.
Prior to resizing the brass was very well cleaned and I inspected it all and found no issues.
The brass showed no signs of damage but did show obvious signs of being worked by the die. Been reloading for 30+ years and never had instance where a sizing die failed to bump back the shoulder. Unfortunately I misplaced my Redding 300wsm FL resizing die so don't have another die to help figuring out this problem. I closely inspected the inside of the RBOSD with a very bright light and the interior looks flawless.
I even used three different types of brass, Winchester, Federal and Hornady, same results every time. Even changed shell holders from Redding, to RCBS and Lyman. I also closely inspected the Hornady headspace bushing and found no damage. I then resized some 35 Remington cases and measured before and after to confirm I had bumped the shoulder back 0.002" to insure my Caliper was working correctly.
So now for the bizarre part. When I adjusted the die down as far as I felt it could safely go Every piece of brass I resized and measured actually GREW by 0.0015" to 0.002". I checked and remeasured 3x to confirm this as accurate.
I feel I have eliminated all possible variables that could be the cause except for the die itself as I do not have a standard FL resizing die to use as a test control.
So am I setting up the die incorrectly, doing something else wrong or is the die defective?