Seating issue

I am using a  Dillon square deal B. Yes, I know I should get a different one but that's a later thing. I use Zero 185 SWC and I can reload jabout 50 rounds with a .030 shoulder then without warning the bullet, on the next  50 will be lower into the case. Slowly but I know the shoulder is no longer .030. Why Is this happening?  

Not sure if this makes sense or not

Thanks

Same length on the cases?

Lube / Crud build up in the seating die-needs cleaning? - or - The blue nylon(?)  block that holds the die adjustment on SDBs is allowing the adjustments to drift?     
I used a SDB for 12 years & for the last 6 years used I'd mark the die adjustments w/ a sharpie, then check the adjustment every 30-40 rounds.   usually my crimp die was the "drifter". I'd turn it the couple °s back to the mark & continue. - Went thru several of those free blue blocks. - At least die adjustments are quick & easy on the SDB.

The 550-w/ the die lock nuts-  die adjustments take longer but stay put.
Russ

I will need to look again even though it was just cleaned recently. 

And yes the brass is the same length. I though that too

I have a similar problem with my Dillon 550B & the Dillon dies. My shoulder increases, not by much, but measurable after about a 70-100 rounds loaded. I know that it sounds impossible but my OAL will increase by .003-,.005. I am a very OCD reloader & I pull the seater die out after every loaded box. I generally pull the crimp die t the same time but it is always the seater die giving me problems. I could probably cancel out some of this by increasing the bell but I don't want to over-bell as it contributes to loss of case life expectancy.

Mightyheb wrote:I am using a  Dillon square deal B. Yes, I know I should get a different one but that's a later thing. I use Zero 185 SWC and I can reload jabout 50 rounds with a .030 shoulder then without warning the bullet, on the next  50 will be lower into the case. Slowly but I know the shoulder is no longer .030. Why Is this happening?  

Not sure if this makes sense or not

Thanks

Does the square deal b seat off the shoulder or nose ?
I was guessing case length variations or lube build up in die

I'll trade you my 550b the new C model has a zerk fitting in the upper pivot pin for that square deal?

What if the lead has different dimensions ? They would all seat differently if pressing on the nose.

Multiracer wrote:What if the lead has different dimensions ? They would all seat differently if pressing on the nose.

Exactly

Unless the bullet to bullet dimensional difference is measurably significant I think that it will be difficult to determine. Also measuring the shoulder to case dimension sometimes can be difficult due to lack of squareness of bullet bottom or shoulder. Also lack of squareness of bullet to the end of the case length varies considerable. I've seen that myself on the R-P nickel brass cases that I use vary as much as .004 around the circumference of the case mouth

Maybe I need to clean it out after each 100 rounds. Kind of a pain but I guess I don't have a choice. Chris did you say you will trade me your 650!for my Square deal B haha

M?ultiple headstamps

How much are we talking here? 10-20 thousands ? Or just a few.

Mightyheb wrote:Maybe I need to clean it out after each 100 rounds. Kind of a pain but I guess I don't have a choice. Chris did you say you will trade me your 650!for my Square deal B haha

550 :0