2,160 ft/sec might be the listed velocity in a rifle, rather than in a carbine. Also, some companies seem to have loaded undersize slugs in these 6,5x54 M-Sch. and so there's gas escape to contend with too in what were often (in pre-1945 rifles), oversize bores. I'm not saying that you'd expect 1600 ft/sec if they were brand new, just that not all that velocity loss might be due to age.

I was recently given some very old RWS 6,5x54 M. Sch. cartridges in a poor state. I pulled the bullets, cleaned the cases in a solution of hot water, detergent, vinegar and salt to a recipe I read in an old Handloader's Digest. That removed much of the crud but they still neeed a very long polish. I loaded them with fresh powder and primers. I have reloaded Berdan, but these were Boxer primed. Must have been made post 1950. I also polished and reloaded the bullets. They fired OK. No neck-split losses but if there had been, I would have also annealed the neck/shoulder in moulten lead for 5 seconds, then quenched in water. I have a heat-sink made up, just a big block of brass, split in 2 with a split-slot to hold the case. The split block is permanently mounted on a pair of vice grips. In this way, the head of the case never even gets warm and I just open it up and drop them in the water.

The guy who gave them to me said he did so 'cause he figured I'd do all that.