It sounds like you are probably getting bolt stick due to your carrier being too tight.
Originally Posted by Pronby
Properly size the carrier first. The carrier and oring should slide onto the bolt stem without much resistance, but should not slide on its own when held in a vertical position. Don't use shims when first tuning your level 10. That way you will know that any leaks are caused by the carrier rather than too many shims.
Use the shortest bolt spring first. That way you will be able to make sure the gun will actually fire, even if the carrier is a little too tight. The shorter bolt spring is a little more forgiving. Once you have the tuning of the carrier size done, you can go to a longer bolt spring and fine tune the operation knowing that it does work.