Size of Webley Cam Lever Fixing Screw

Still looking for a cam lever fixing screw for my Webley .380 MkIV and I've had an idea for a possible work around...

Could anyone confirm whether the cam lever fixing screws on the .455 MkVI and the .380 MkIV are interchangeable?

If so, could anyone confirm if the following description of the dimensions of the MkVI screw is accurate?

"Head : 0,304", screw length (under the head to the end) 0.25", major diameter of thread : 0.15", 36 threads per inch, Whitworth".

Or better still, does anyone have a specific reference for the dimensions of the MkIV screw?

Thanks,
Mark

The lateral retaining screw or the rotation lock screw in the "tail"?

https://www.milsurps.com/images/impo...stuff006-1.jpg

Without a .380 Webley for many years, but might could dig out the .455 in a few days.

Thanks. It's the latter. I note that Apex Gun Parts use the same picture on their website to illustrate the cam lever fixing screw for the MkVI and MkIV and was wondering if that meant they were interchangeable? Having tried it, I know that the cam lever retaining screw on the MkIV will fit in the hole for the fixing screw although it's slightly too long to be an exact fit.

Looks like the same:

1922 Enfield Mfg. Mk.VI .455

OAL: 0.400"
Shank and thread OAL: 0.290"
Head OD: 0.30"
Thead OD: 0.150"
Slot width: 0.100"

4 threads span 0.106-0.110" using calipers
7 full threads over 0.200" +1 runout thread at top and +1/2 thread at bottom w/some taper.
Averages out to 36 TPI! (No pitch gage at the revolver's location, nor thread mic.)

Brilliant. Just what I needed to know. :)

There's an outside possibility I might be able to get an original one at a military history show on Saturday, but if not I'll open negotiations with Evans Obsolete Screws to make a replica.

Thanks again,
Mark