Need help with a front triggerguard screw fitment issue.

I removed a Parker Hale front trigger screw, the one that is triangular and swivels, from my No.4 MkI. I had it on my rifle for ten years or so, but never used it with the sling. I sold it to someone who now says it won't fit his No.4. Was there a difference from one manufacturer to another or from a MkI to a MkI* to a MkII? Using my Brownells screw checker on the original screw, it fits the 1/4 28 threaded hole. I never checked the PH screw, but the buyer says the thread pitch is too fine. I had no problem screwing it into my rifle, and there were no thread damage when I removed it. Any information will be appreciated.

I know the swivels were made threaded for both the SMLE and No.4 but that doesn't really equate to your problem. Very strange.

Here is the swivel I sold.Attachment 53979Attachment 53978

If you are 'reading' 28tpi then there is some wear or damage somewhere.

The No1 Mk3 front trigger guard screw is 0.25" x 30tpi (Enfield special)
The No4 front trigger guard screw is 0.25" x 26tpi (1/4 inch BSF)

See if you can get a 1/4" BSF bolt and try it in your No4, or - try to get your 'customer' to source a 1/4" BSF nut and try it on the swivel mount.

If it helps, the swivel may be marked with a PH list number.

215J = No.4
215D = SMLE
215F = P14

If you took it out of your No4 and he says it won't fit into his then one of them MUST be wrong. I'd tell him to send it back and sell it to someone who will appreciate it!