It's likely that your having intermittant light firing pins strikes. Sometime quite hard to diagnose.. Sometimes in welding the new handle in place the bolt body is not returned far enough to the right, bolt down, for the firing pin to clear the safety cut out in the interior of the bolt. Also the cocking piece lock may be allowing the bolt handle to raise a bit. This causes the sear to hit the cocking cam as it's falling. This slows it down and can create poor ignition and hang fires.. Making sure the bolt handle is completely down before firing should eliminate the problem initially although a smith should be able to make it a permanent fix by altering the bolt handle and bolt shroud lock relationship. We must also check the rifle for excessive headspace and a weak mainsping(striker spring.. Also check the firing pin protrusion.