Interesting, haven’t heard of all the issues in one rifle before lol.
1) failure to feed issues I’ve found to be purely from magazines. I’m told gen 1 (all I’ve dealt with) is worse, but as long as the magazine is good, zero problems. You want the magazine to be fairly tight. I’d say fitting but not drop free even. If it can tilt forward in the mag well, Itl ram rounds into the feed ramp.
2) wandering zero - there really isn’t much to the gun so only a few things could actually cause it. I doubt you’re forcing it down into the sandbag, but that would do it, since the barrel and hand guard are all attached to the receiver. Worst case scenario would be either a crap barrel or receiver with residual stresses causing movement under slight heating. I’ve never had this problem. I’ve had my T97.Ca upper come loose, but if that was solid in your test.. shouldn’t be an issue.
3) trigger reset issue. My friends gen 1 had this issue when using a T97 LHG, but worked for the factory lower with the stronger spring. Again there isn’t much to it, make sure the trigger bar doesn’t have any burrs or edges catching. Make sure the trigger pack itself moves freely.
His was also sent to north sylva for the trigger but they sent it back saying there was no issue.
If you need any help checking on things let me know, I have a couple gen 1 I can compare to.