No. 4 Sling Swivel Bolt Length

[BobGee]

I have tried a search but cannot find the information.

I have a No.4 Mk II (Fazakerley) dated 1955. I have found a target sling swivel to replace the front trigger guard screw. The bolt thread is the correct BSF 1/4" 26tpi but it is considerably longer than the original trigger guard screw. I notice that this is also the case in the drawings in the Canadian documents for the No.4 - see attached drawing. I believe that the swivel I have is a commercial one as portrayed in Mr Laidlaw's post on modifying a commercial sling swivel to resemble a military one.

However, I would like to ask the question: why is the sling swivel screw longer than the part it replaces, and should I shorten mine to match the screw it replaces (unlike the Canadian docs)?

Bob