First thing: No I do not know how to do this and this is not a tutorial. Now to my point: I am almost finished with the game on Veteran and have been stuck at one checkpoint in Blowtorch & Corkscrew (not looking forward to the next ones). I would play for around 20 minutes, advancing, killing the guys, everything and would never get a checkpoint - so I just forgot about it for a few days. Well before picking it back up I was playing with a friend on competitive coop for the achievements - mortar-dom, death cards, saving private ryan, etc. We were basically boosting those for him because we were playing on Recruit. Well I went back after almost going through the entire game on coop with him and resumed my checkpoint. I had not played this level, watched any videos on how to beat it, or even played veteran in like a week yet somehow I breezed through the level like it was on Recruit. I barely got shot, never died, and beat it in like 10 minutes (remember before I couldn't get checkpoints even after 20 minutes). So I'm suggesting that there is a way to get to a checkpoint on levels that you started in veteran, do something with coop and recruit, then come back to your checkpoint via 'Resume Game' and basically the difficulty gets reset to Recruit but still counts as Veteran. This could be entirely circumstantial but you should have seen me after resuming that checkpoint - I swear it was not veteran - no way. Has anyone had similar experiences or interested in trying this out?