Hmmm reading this several questions come to mind so here goes:-
1) What is your usual group size when shooting ?(I am assuming that you have another rifle at least)
2) The rifle is a new CZ 550 what is the scope and mount set up?
3) Is the scope known to be good?
4) You said that the barrel is free floated "The range master checked". Hmmm just how much experience shooting wise are we talking here?
5) Is the rangemaster the gunsmith type and how much experience and knowledge does he have?
Now you also mentioned that you cleaned the rifle before the last shooting session. Well quite a few rifles will throw the first few bullets from a clean barrel out of the main group. So before hunting you need to find out if this is the case with your rifle
if it is it's not a big deal just don't clean it before hunting after the last sight in session.
Otherwise it's back to basics. Start from the basement and work up checking everything. I am not familar with the 550 model having the older Model 601 so that makes it a little more difficult to help. Now the old 600,601 & 602 models did not have a free floated barrel and shoot very well indeed
the bedding on them was good from the factory but they were made completely in the Czech Republic, not sure about the 550 so I wonder if there is a quality finish issue ............ possibly bedding as free floated barrels are the cheap way to bed a rifle which accountants love .
However you need someone who is good, knows what they are doing and is well experienced to check it over. Now a quick easy and cheap way to test the bedding is to get some thin card. Business cards work well. Cut and put it pieces as shims under the barrel in the channel about 1 1/2" back from the end of the fore stock and try shooting again. You may have to try a couple of times with more or less card and see if it tightens the groups or throws it wider. However you need the check the Mounts and the scope and the actions screws as mentioned before by others before trying this.
Now if pressure from the card shims tighten up the group then you need to either bed it yourself or get it done. I have a P-H 1200 super which hates any free floating as I found out by mistake
added too much bedding material and acidently free floated it. Groups were terrible about 6-8" at 100 yards
with it floated . After bedding with a pressure point it now hovers around the 1 MOA to 1 1/2 MOA groups with factory ammo.
Oh sometimes you are luckyand find the brand/load which your rifle likes straight away, others it takes time and unfortunately money to get there. Good Luck with the grouping and the hunting
.