Make a small ball of clay, put round in chamber, close bolt on clay behind round, open bolt slowly, if the clay doesn't tear you can measure it with a dial caliper.
You can also use masking tape, one layer at a time, tape over rear of bullet, trim with razor. Insert in gun close bolt, repeat until you have layered enoungh tape untill the bolt closes snugly, when it closes snug, peel layers of tape off measure thickness with a dial caliper. The thickness of the tape is your headspace.
I don't rember the max headspace on a 06 but you could google that.