Turkish you are varying holds and going from hand held to (l assume) firm sand bags which may cause more "bounce" from a firm rest. Especially if the barrel is bedded in the forend.
Add in that we really don't know runnout of the neck sized brass and any of these things can effect groups day to day. That said you will get a truer picture of the rifle's capability if you get it out to 300 yards. If it does well there, l would stop worrying about 100 yard groups which are just a place to begin but hardly an end game in and of themselves.
