Occasionally I have trouble opening the bolt on my gun after firing. I have been full length resizing. The primmers are slightly flattening as well. I have tried numerous recipes with not a great deal of luck. Mostly seating bullets .010 off the lands. Its a 1:11 twist 23" Kimber Super America. I have been shooting 5 and then cleaning. Bottom metal screws are 40 inch pounds.
1. If you have no trouble closing the bolt and do have trouble opening it, the pressure is too high. How you size only has relevance if you're having trouble closing the bolt.
2. Primers are always flattened to some extent.
3. How far you seat the bullets off the lands probably has not much to do with your problem. I have never measured the torque on bottom metal screws on any gun I've ever owned; it's unlikely that has anything to do with it.
4. Some guns shoot better a little fouled. Your shooting 5 and then cleaning may be your problem. Try shooting 3 fouling shots and then shoot some groups. Then, depending on your gun, you may need to clean after every 20 to 100 rounds (really). If your last coat after cleaning is oil, stop doing that.
5. You might disclose what powders, bullets, etc. you have tried. It's unlikely that a 308 Winchester of good quality won't shoot well with IMR 4064 and decent (maybe even indecent) 165/168 grain bullets.