Have a RRA CAR A4 Midlength SS upper.  It currently has the standard handguard.  I realize that free floating the barrel will help imporve accuracy.  I was wondering if there was a way to test an AR's accuracy before going to the trouble of switching to a FF tube.  If I say, removed the grip to take tension off the barrel, loaded rounds one by one and used the mag well as a rest would this help to test potential accuracy?  I want to see if this AR upper is worth converting into a SPR or use as a blaster.