Just some ideas.
How about saying if you offer a 2 tone service on the guns that you need a UKARA to purchase said gun so that people that don't have a UKARA can still get it.
if you do not want to offer a 2 tone service then say you can get said gun in 2 tone but there will be a wait as you have to order it in.
Have a I am looking for this gun but you don't have it on your site ask if you can get it in and how much it is going to be page.
do you price match if you do say you do on your site
if you do price match why not go one better and say that you will beet others by a pound and still let people use the facebook 10% Discount that you offer on top of that.
I see you do Bundles how about doing a build your own Bundle say letting people pick a gun of there choice and other Accessories then they can hit a button that sends there bundle to you and you can get back to them with a bundle offer.
this last one might be a bit harder to get up and going.
do you offer a trade in. if so maybe put a list of guns you're open to taking in. put up a email address so we can ask you for the address to send it to and what we are sending in for you to look at.
say on your site that we have to pay postage to you and back to us if the offer you make on it is not what what some one was hoping for.
or have the list with a up to x amount offered on it