Bullet weld - Norma brass

[PeteFox]

I have discovered a problem with moly coated projectiles and Norma brass.
A couple of years ago I had a very bad batch of hand loaded ammo to the extent that it basically struggled to hold the 4 ring. This was during a Queens, (the ammo shot fine when loaded but sat for a couple of months before the Queens). I put the ammo aside and started another batch and the problem went away.
When I got home I decided to pull the ammo to recover the projectiles. A kinetic (hammer type) bullet puller wouldn't move the bullets (180 Berger hyb) so I resorted to a collet type puller on the press. The bullets were gripped extremely tightly, a slow pull on the press handle resulted in a destroyed bullet with grooves down the side, bullet still jammed, I found I had to thump the press handle to get them to move. This was using moly coated 180's, moly coated necks and Norma 6.5-284 brass, necks were mandrel sized 0.283", annealed, trimmed and chamfered.

I put the brass aside and have had no problem since using the same methods but with Lapua brass instead. It can sit for months and still shoot.

Recently I decided to use the same batch of Norma brass in a 30-284 I am playing with. Using the same methods with Berger 205 hybrids I have struck the problem again, but much worse than before as the photo below shows. Second photo shows copper-salt deposits (I think) around neck bullet junction.

Lapua cases in front, Norma at rear, same storage, same powder, same projectile, same load date, the only difference is the brass.

cases1.jpg

cases2.jpg

These bullets were loaded about 3 months ago and they are STUCK! I have fired these rounds previously, straight after loading with no problem, but I won't be firing these as I imagine pressures will be way over the top and I don't know what the effect of those salt deposits jammed between bullet and barrel at 2800 fps will be.

There is some information in the literature on 'brass~molybdenum- disulphide reactivity' but not much, but plenty on bronze bearings treated with moly being destroyed. I am wondering if there is a small amount of tin in Norma brass which is attacked by the moly.
Am I alone in this or have others had this issue?
Brass is going into storage in the round filing cabinet.

Pete