[andolini]

I acquired this rifle and noticed the third swivel in front of the magazine. is this a sniper swivel
no 4 mk 2, PF 174xxx

 

[John Sukey In Memoriam]

More likely for use as a target rifle. The Brits used the triggerguard sling position for that. I would guess that swivel is either an A.J. Parker or a Parker Hale product.

 

[Hal O'Peridol]

From the pic it has the longer shaft. So is purely an aftermarket target swivel.