For what it's worth, similar experience with the .35 Rem in the Contender - G1 and G2 frame.
This was likely a headspace issue, wasn't exactly uncommon with the .35 Rem chambered barrels on Contenders. I think the fix for most people was to seat bullets out into the rifling to fireform brass, and neck sizing afterwards. That being said, I never had an issue with the 16.25" .35 Rem barrel I had years ago.
