The issue is to find out why the pin is loose. Sizing isn't a problem. Stopping on the link, or the barrel hitting the frame bed before hitting the vertical impact surface can be a barrel-destroying problem. I've seen lower lugs pulled loose from the barrel...a few all the way through the chamber. Bad JuJu.
What do I need to measure/look for?
I didn't see any wear that just stood out on the link, but I didn't check it too closely.
The pin is gone, it fell into the grass by the well house and might have even caromed off the concrete base around the well house and bounced who knows where.
I actually took the bag of parts that was a gun back home with me.
If I could get a measurement on the link diameter and replace it with a correctly sized pin, it should be good to go, assuming nothing is wrong with the linkage?
I just thought of something, it is a Springfield Armory. I wonder if that would be covered under their lifetime warranty policy?