Webley Raider XS10

Ok guys and girls i have a secondhand webley raider xs10 as it is labeled , now the problem i am having is it is said to be a post 2006 model ,the power was lower i have stripped and rebuilt it all going good when fired the power is low i turned up the hammer spring and that should increase power but not really i am lossing pressure from the pellet probe , how i know is i loaded a pellet and put a little talc round the probe then fired and the talc puffed up now there seems to be the problem but the probe has no seal on it and there is a seal inside the barrel , when i look at ordering this seal it appears i can't it lists seals for the probe but not the inside barrel now i am wondering has the gun been made up out of other guns and thats why the problem
any help would be great as i say lovely gun just a pain right now
many thanks

Have heard of this a couple of times, I have a Viper which is a raider 2 shot the only problem with these is they are "Venomized" and the seal is an odd size but the seal is on the prob' now I also had a Hatsan AT44-10 and the seal was in the barrel so possibly your rifle is a Turkish one I think made by Hatsan !

I think the easiest thing to do is carefully hook the old seal out, go down to your local DIY/hardware shop and look through their box of seals until you find one of the rite size, then buy half a dozen !

Good luck !