Hey jeff- the rifle seems to me like it had it's headspace set on the outer limits, and the 9.3x62 has a mild shoulder angle. I got light primer strikes on a several factory loads ( both the cheap PRIVI 285's and the very expensive Vortex 286TSX) of course, when I recocked it, they went off. I didn't have time to try and work up a reload on fired cases as I don't have but just the few fired cases, ha. I don't believe it was a light firing pin spring,etc as the fired primers all show great strikes, like my old 1917 Enfield did! ha. Well, going on a money hunt, after a hog that can cut me from ankle to crotch, hearing that rifle go "click" spooked me, ha. My Whelen has had "all" the bugs worked out of it, what few it had, but it "always" went bang! Plus, my fireformed Ackley cases are perfectly headspaced on that sharp shoulder, but heck, I never had a standard Whelen round FTF in it. I have had similar FTF in a custom .404 Jeffry I had made up, shooting factory ammo. It had the long sloping shoulder and I think there was just enough "give" between the oddsize case and the chamber.
Now, I had a Ruger MKII in .338 WM, back in '93 that shot the Remington factory 250gr ( it was the Speer GS they used too) into bug holes. I had 5 boxes of the stuff. When I tried it handload for it, I had 8 out 0f 20 FTF. I tried everything, then finally figured out it was headspaced on the outside limits. I traded that thing off for a gem-dandy Mod 700 Mountain Rifle in .280. I've owned a total of 3 new Ruger 77 Hawkeyes, a .338 Federal; .257 Roberts and this 9.3x62. Only the latter was a problem. No matter, I found someone who wanted it more than me, sold it!!! Yep, the 9.3x62 is GONE! I am just too fond of my old Whelen Improved. Besides, I gave my SIL a CZ 550 FS in 9.3x62 when he married my daughter, and it goes "bang" with everything, so I am givng him all my ammo,etc. I can shoot it anytime I could ever pry myself away from my Whelen, ha. I "may" be just getting crotchety Jeff! I find I have less time to load/shoot so I am more focused on hunting like never before.