1886 with assembly number?|Winchester Rifles|Forum|Winchester Collector

I recently purchased an 1886 and after checking it over I noticed a small 3 stamped on the lower receiver next to the bolt locking lug. Reading through Arthur Pirkle’s book it says special order rifles often had assembly numbers on the lower tang, left side.  This 3 is on what I think of as the rifle’s right side, but is on the left side if the rifle is upside down to where you can see the number. One of the first things to come to mind when I got the rifle is it was really heavy. Sure enough, from measurements in Pirkle’s book it seems to be a heavy barreled rifle and may be a special order rifle. I’ve got a letter ordered for it, but thought maybe I could learn more from the group in the mean time. Is the 3 where an assembly number should be? Pirkle’s book says lower tang but this is on the receiver. 

Thanks,

Jeff