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

[Surpmil]

If I understood you correctly the screw is longer because it's intended to get the sling loop above the little "U" loop on the guard made to hold breech covers in place.

Peter has said in the past that those were often removed from No.4(T)s in the postwar era to avoid fouling the swivels - some are not as tall as others.

[Alan de Enfield]

Peter has said in the past that those were often removed from No.4(T)s in the postwar era to avoid fouling the swivels - some are not as tall as others

If I remember correctly the swivel that will not fully rotate is the original military issue version - the one that swivels thru' 360 degrees and puts a twist in your sling, is a Parker Hale after market swivel.

[BobGee]

I managed to find the dimensions I needed (though no answer as to why the thread lengths are different) to modify my sling swivel and to borrow a 1/4” x 26tpi BSF die off a mate. As I walked away from him he said you might find it's hardened (the screw that is). He was on the money. I got home and ran a file across the shoulder and, true enough, it is hardened so I've decided to leave mine as is and will try and not twist the sling! I don't want to get into grinding the shank and annealing the shaft to extend the threads. Looking at the photos in Mr Laidler's article, I think he must've ground the shank.

WRT the threaded length, I surmise that the extra length is provided to increase the anchorage on the screw to help resist the lateral force on it from the sling. It was that force/moment which I had hoped to minimise with a reduction to military spec of the shank. However, it doesn't seem to have bothered users of the commercial sling swivels like mine so I see no real problem in leaving as is - I’m not trying to make a faux No4(T).

Bob

[Surpmil]

If I remember correctly the swivel that will not fully rotate is the original military issue version - the one that swivels thru' 360 degrees and puts a twist in your sling, is a Parker Hale after market swivel.

Could be, I don't know! All those I've seen apart have a simple groove all the way round into which the two ends of the loop are pressed thereby retaining the loop and swivel on the threaded stud or bolt. I've got six or eight in a box here, including a couple not assembled. Have had some Broad Arrow marked, but don't remember any with restricted rotation.

Restricting the rotation would be done by only cutting the concave groove part way round, or putting in a pin or two.

[Alan de Enfield]

The depth of the swivel is different on the military and the civilian versions. The military version is manufactured so that the swivel fouls on the 'staple' used to secure the breech cover.
The civilian version is made deeper so the swivel 'sling loop' clears the 'staple' as it rotates.