Well, I finally got out to try that new replacement mag today, in between rain storms. The new mag seems to feed 100% of the limited time I had to play with it. No jams at all. I still have an issue that seemed relatively minor before, when I was unable to string more than 3 shots together.
About once every 20 or 30 rounds, the bolt will lock back and needs the charging handle pulled out to release the bolt and chamber the round.
It's not as annoying as the jams I was having before and it's lots easier to clear. It seemed to be improving with use and when the weather and my schedule permits, I'll wring it out some more.
I do like the trigger and general feel of the gun and once the bugs are gone, I'll dial in the sights.