things you will need ,
1 blow torch 2 nail in a bit of wood with the nails head cut off and made in to a point or a small thin pozzy drive screw driver,
3 a boot lice 4 an old cycle inner tube 5 dog brush or wire brush .
you do not need a sling , as you have one on your rifle bag ,
use the hot nail to push through one of the holes on the rubber but plate ideally a hole just above the fixing screw and close to the wooden stock . then push the shoe lace through and tie a knot and pull it tight so the loop cannot move back around the but end, then tie another knot about 20mm away from the first knot then cut of the wast ends leaving about 2 inches , use your brush to make the ends like tassels . you may find that there is a fine weave inside the lace, if so slide the outer back and cut off the inner section , then brush , start at the tips and work back until its a nice tassel. your back loop is now finished ,
now the barrel end make sure its clean of oil , cut a 2 inch section of the inner tube , wipe it off, turn half inside out ( the inside is now , on the inside and out side ) place next to your barrel , if you are right handed have the lace coming off to the left of the riffle just out of line of the cocking arm,
put the lace as a loop through the tube then put the loop over the barrel so the first pull together is away from the stock, pull hard until the rubber is covering the lace , now keep pulling and put a knot in the lower end keep pulling so all the rubber is covering back on to its self , now about 20mm down the lace put another knot and cut off 2 inch long to fray to make a tassel like the back. now you have your front clip ,
now take your strap off you gun bag , put it on you riffle using the loops you have made on your tassels , put the shoulder pad at the front end as this is nice for the back of your hand , if you have not got a strap on your gun bag or its a fixed strap . look on a sports bag etc , as now you can clip any thing on as a sling , i find the plastic swivel types best but any will do,
i know the strap on my bag is a different colour , as i have that strap on my pro sport,
AND YOU CAN TAKE IT OFF AND USE IT ON YOUR BAG FOR ON THE WAY TO THE RANGE THEN PUT IT ON YOUR RIFFLE
ALSO TAKE ALL OFF AND NO ONE WILL EVER KNOW YOU HAD A SLING ON YOUR RIFLE,
. You could also place a piece of folded leather between the stock and but pad to make a loop 
,then you wont need to make any holes.