It is rather irksome and yet another reason to recommend https://www.ak2m4.co.uk/ who charges low rates. He's probably making a loss on postage + packaging + time.
@Rogerborg Thanks, and yes making a loss. However my postage fees are due to rise in the new year when I switch to more of a fully tracked system. I might still keep the cheaper large letter sub £20 sub 100g rates, not made up my mind yet.
I think the problem is GBB makes up such a small % of sales so most are reluctant to stock parts which is a shame. Back in the day when I was into GBB everything had to come from Hong Kong but at least you could get it all from 1 store ?
I was going to order a spare mag for my P99 from A2 supplies till I got to the checkout and found the only shipping option was a tenner for next day delivery which was adding almost 50% to the total cost. 2 minutes later I found another shop which had 2 day delivery at a lower price so went with them.