I am a big fan of the 303 British, very good round although that is one round I don't reload so I can't give any info.
The grenade luanchers usually have wire in three places. One where you mentioned and two wraps of wire in front of the receiver and on the forward part of the fore-arm.
As mant things that has gone on since that rifle was made it is hard to tell.
Maybe the stock is cracked under the wire, or maybe someone removed the other wire bands, maybe it just had one to start with.??????????
That round has taken it share of deer around this area.
My mk4 no1 will a 9'' steel plate all day long at 400yrds with stock sights.
It is my most accurate rifles at long range, with open sights.