I don't shoot a great deal, mostly only to sight in and at game.  My Armalite a10t was one hole accurate using Horndy 150gr bthp steel match.  Well the range I went to doesn't allow steel casings so I bought the 155gr American Gunner they had.  My groups open up to 4+ MOA. I was trying to sight in a new thermal and it was shooting all over the place.  I dare say this gun has fewer than 80 rounds through it.   Is it time to deep clean or do you think it was the ammo?

The only answer is...........  Clean as Needed.

Probably ammo, any number of things rather than the 80 rounds through the barrel. 
I don't get serious about anything(load dev. shooting groups, etc.)  until I have 80 rounds of fouling.

It is unlikely a cleaning issue.  If you have time to spare, clean it.  

I was wasting time last weekend, so I cleaned 4 rifles.  At least I had something to show for my time.  

Good time to check your scope ring bolts and your gas rings.

Definitely put a couple hundred rounds through it.  Once you clean it, make sure it's fouled out (round count differs on every gun) before you try  to do any precision work.  If you're trying to see how well a rifle will shoot, i wouldn't be using a thermal.  Make sure it shoots how you want to before trying to sight in a thermal.