Irun lapua brass in my 7mm AM, have never had a loose pocket, the cases get work hardened and pressures go up.......in hot weather they go way up, at 80 degrees it will push a .284 160 gr accubond at 3700 fps, and pierce the primer but the pocket is still tight.
if your loseing the pocket with lapua brass you are way overpressure for some reason.
RR