"cold weld" or whatever it is.....

[J. Valentine]

Exactly as I said in my first post I brush, casually, briefly, without much effect, just to get the loose stuff out. I don't polish. I use a nylon brush and just knock the loose stuff out deliberately leaving a layer of powder residue in the neck. I don't want to see brass. I don't use a brass brush and I don't use steel wool and sticking the case over a spinning nylon brush takes very little time. Have I misled you somehow? So am I cleaning? You can call what I do whatever you want.



Well I thought I was. There is powder residue left in the neck that touches the bullet. I do that with intent, knowledge and deliberation. And I get results doing it that seem to work. Let's see, I get accurate ammo with less work and time spent. Hey, maybe someone would want to know that! Or not. Am I seating in a dirty neck? You tell me.

Your photo with the shrunk necks looks like snakes after a big meal! I don't think I seen that before. How much do you think a neck can shrink?

Greg

I don't know how much a case can shink but under the worst conditions it's enough to increase neck tensions dramaticly in some cases. Even split the necks. If you look close on the case neck with the naked bullet a fine crack is forming from a slight nick in the case mouth . The photo may not show it well.
Also the shorter molycoated bullet has been slightly ejected from the case neck by the shrinking brass. You can see the edge of the new untarnished moly surface just out of the case mouth.
The overall effect is wide variation of neck tension.
Brushing case necks has been the normal accepted way to clean a case neck prior to reloading for a very long time so it's not in my view regarded as seating into dirty necks. You have brushed out all of the loose powder residue which is the main issue.
For me a dirty neck is an uncleaned , unbrushed neck , containing all the powder residue buildup of every loading .
Yes you are cleaning your case necks by brushing.
You don't have to brightly polish up the case neck if you don't like it some do some don't .