Thanks TM,
Posting here for "completeness" made sense to me as well.

I think my stock looks like the one in the ZKK 601 add, however I think it has the ventilated pad of the others. I'll have to wait until I see it, but as I said, I believe the stock to be in its original finish. Also, I think that the fixed sling swivel loops have been removed in order to have some QD ones fitted to the original sling swivel points.

You have convinced me to steer clear of the 358NM chambered ZKK 600, but I still want to now what the issue is, ie not enough meat in the chamber shoulder area etc. Was the 358NM loaded to much higher pressures when factory ammo was round?

George