"but when the bolt is brought to the rear there seems to be a fair bit of movement, ie while holding it the rear seems to be fairly free to move up and down, side to side"
Yes it is normal. Parker H went out of business, the name moved east, then changed names to Midland, then Gibbs, then the 'what was left' was shipped to Navy arms.
I have 4 receivers, complete with 03A3 Bolts. The receiver ring is made like a small ring Mauser/03 Springfield, the barrel seats on the front of the receiver, not on the bolt face.