Neither did I, I had MP5 mags, a Gun Bag, Mesh Mask and a Optic sight, I got a letter from Border Force and spoke to the Officer in charge, gave them my details and my UKARA number and all was happy.
Seems strange as I have had 4 RIFS delivered with no issues from gunfire.pl this week but the box with 40k 0.23 bio beebs, sniper optic and m14 scope riser got stopped.