With just the bolt and FP in hand, insert the FP into the bolt and confirm that the FP protrudes .032 to .037 out the bolt face.
Next question that comes to mind, are you sure that the bolt was fully locking up each time that you had the light primer strike.
A rig run dirty from the start (read not fully cleaned before it fired the first time), not correctly lubed, or with question mags may short stroke and/or not fully lock the bolt up each time. A bolt not locked up will end with the back of the bolt blocked by the back of the carrier, and although the hammer may release to strike the primer, with the carrier blocking full protrusion of the FP, it off ends up with the hammer force closing the bolt all the way, with a primer strike too light to ignite the primer.