Ala Dan, my friend, my guess is that you are referring to straight wall cases such as .357 where the sizing die doesn't quite reach to the rim because of the shell holder.
This is a case where tumbling afrter sizing will help camoflague that a bit.
Of course you could have a tight sizing die. If you have a bullet puller pull 2 or 3 loaded rounds of factory ammo and then resize the cases in your dies to see if they come out the same way. If so your die is a little too tight.
I had a set of RCBS .38/.357 carbide dies that I bought new back in 1976 that was like this. They replaced the sizing die for me no charge. That was back in the old days, when RCBS dies decapped in the expander die.
NavajoNPaleFace are you a carbide sizer?
By the way that replaced RCBS .357 carbide sizing die lasted well over ½ million rounds.
As did my .45acp carbide sizing die. Well over 500,000 rounds
I had a Lyman carbide .44spl/mag die last well over 250,000
And I still have my original RCBS .41 mag carbide die that is closing in on 500,000.
At least 50% of those rounds were sized without tumbling.
A good carbide die will in fact clean the case for you.
An old fashioned standard sizing die will indeed imbed the grit and grime in the cases because the sizing lub will act as a lapping compound. You'll get scratehed cases and eventually the die will become scratched as well.
I loaded commercially for almost 2 years before I even bough a tumbler.
I ended just having SIX Thumblers Model B tumblers working 24/7.
Four for polishing before loading and two more for final polish, after loading, on my premium ammo.
I learned early that people would gladly pay more for the shinier ammo.
The tumblers really did pay for themselves.
Of course just because I have loaded over 4 million rounds of handgun ammo so far in my lifetime doesn't mean my opinion is worth any more than you have paid for it.
