Last week I got a new in the box 1991 vintage BRNO ZKK 601 in 243. My gunsmith had taken it off of a gunsmith pal of his in the mid 90's when he retired and since then it has just been sitting in the shop. I took it home loaded some rounds and started the shoot one and clean routine, then worked up to shoot three and clean. Then came the big moment of firing a five shot group for real, could hardly load the the thing it was taking a load of pressure to push the rounds down into the mag. Then they would not feed it was impossible to work the bolt and feed the rounds. It was OK with one round and with three, but the extra pressure of five in the mag was just throwing the front of the round up at an impossible angle for them to chamber. Back at the gunsmiths he had some old actions from the same model BRNO so we changed springs in the mag, this was a bit better but not much we tried another and bingo, it worked perfectly. Don't ask me why but three springs from supposedly identical actions were all different strengths, different to point where just compressing them by hand you could feel the difference. I am just glad he had those old actions I would like to have to go through that procedure with the manufacturer, especially if they had provided a replacement spring that was almost as bad as the original, can't really see them going for a second replacement, that is if they had any I don't think spares for the 601 are too common nowadays.
My smith tells me that he has never come across this before, I made no charge for increasing his knowledge base.
John
