I believe this to be a 410 but the length has me thinking.
Measurements taken as an average over 3 cartridges (The rim and head are within 0.001" of each other but the tubes have been dented over the years).
Rim = 0.529"
Under Rim = 0.480"
End of Head = 0.460"
Brass @ Head = 0.447"
Brass @ Mouth = 0.430"
Weight = 22.4g
O/A Length - 3.251"
The over shot card appears to be very hard (perhaps wax impregnated) I am tempted to unload one to check the contents.
I don’t think the shape of the mouth of the cartridge should be shaped as per the photo, I would put this down to wear & tear over the years, all three checked had very different “dent” patterns at the mouth.
The other 2 I checked have a much smoother finish to the top covering so I used this one for the photo as you can see that it appears to be felt (or similar).but as I said previously it is hard.
I can find no markings on it, but the method of manufacture would lead me to say manufactured by Eley.
Any thoughts anybody.