Military cases have thicker walls so, yes, given the same internal pressures, mil cases may expand "more".
If it were me, here is what I would do (there are many on here smarter than I am and may tell you something different):
1. First of all, check to make sure that your cases have been trimmed properly. A long case could cause the neck to stick.
2. Clean the chamber thoroughly. This means getting in there with a new/tight chamber brush, soaked in solvent, and polish it up good. Follow up by patching the chamber out clean and dry.
3. Remove your gas plug and clean up the piston and inside of the cylinder. If your piston has a lot of carbon on it, you can soak it in Hoppes #9 overnight and get most of it. KG-1 works really well and much faster. After your piston and cylinder are clean and dry, reinsert the piston and tighten the plug. After locking the bolt back, you should be able to tilt the rifle muzzle up and down and hear the piston sliding back and forth.
4. Check the dimensions of your sized military cases with a case gauge to make sure you're sizing them properly.
That's what I can think of for now. Hope it helps. Like I said, there are many on here with more experience and knowledge than I so some good info is inbound.
That load sounds too hot for military cases. The Sako factory 150 grain 308 Winchester load uses 45.5 grains of VV N-140 in a Sako commercial case.150 grains FMJ ball ammo, Vit N140 powder 44grs. . :0