Originally Posted by Brameldballistics
Just googled WFTA this is in their rules
Rifle accessories allowed
A single rifle sling - no additional straps are allowed.
A sling used to carry the rifle or as a means of steadying the aim. Such a sling shall be attached to the rifle at a minimum of one and maximum of two points when a shot is taken. The sling may be unclipped from the rifle when not in use.
So why is it an issue in the UK?
Be aware, that I maintain the WFTF website and update the rules, the rules you have found are soon to be replaced with what I posted above your post.
The WFTF rules will be very similar to the BFTA rules for the next World Championships.
The delay in updating the WFTF Website is due to the fact that we still have some voting to conclude on some of the changes and also because I'm very busy doing something else at the moment. They will be updated in plenty of time for anyone going to Portugal though.