I've ordered lots of stuff from ToW since I first started making flint longrifles about three years ago (though never a rifle parts set from ToW - my two long guns kits so far have come from the excellent Jim Chambers). Most recently, I had a tin of Kasenite, which arrived in less than two weeks, and then a mixed box of all kinds of reloading and cleaning bits and pieces, and a few other things that struck my fancy (and there is a lot in their catalogue - beware!). I've had some guns parts in the past from them such as lock parts but not since the law changed. There is no rhyme or reason as to what gets opened at the border - sometimes stuff comes with a big additional customs cost, sometimes not. In my experience they are an excellent company to deal with.
And - their Archive on the ToW website is a remarkable resource for builders, with all the guns they've sold over the past years - hundreds of them. The detailed close up pics are invaluable. I spent hours looking at it when I first began building and it's well worth the small subscription fee.