.30 to 7.62 Mag Conversion

The obvious question is why should someone bother to do it when there was a purpose made magazine already available but someone has put a lot of effort and not a short amount of skill in doing this.
I should point out that this magazine is fitted to a commercially converted No4 Mk1/2 action and is on a ABS stocked sporting rifle with a shortened barrel that has been screw cut to accept a moderator.
The magazine now is a 5 round single stacker but because of the modification weighs much the same if not more than a full ten round magazine.
The information on the side of the action which has not been altered reads;-
No4 Mk1/2 (F) FTR
/53-M13902

The title should of course read .303 to 7.62 , finger trouble on my part.....

Wish I'd thought of that when I had one of those converted rifles. We tried to make the existing mags work to no avail and the Sterling convert mags were all but unavailable.