Bob ... I made it to the gun show today. Place was full. Out of everything being sold there I only found 2 JP BCG(s), 1 DPMS .308 buffer and no other buffer parts. I only counted 6 finished rifles there, 1 Armalite DEF10 and the rest were RRA and DPMS .308(s). Nothing else except ammo and plenty of AR15(s) and AR15 parts.
One vendor that has actually received some Spike's .308 lowers in actually pulled them from their display because the were absolutely bare and still cannot get the Spike's lower parts kits in and other related parts.
Either the .308 is not yet that popular here, or they are extremely popular and nobody can keep parts on the shelf.
I took measurements from the JP low-friction BCG with my digital calipers. I hope I hit the same areas you measured previously:
Under the gas key: 1.0680 diameter (this is right under the tip of the gas key where it slides over the gas tube, top to bottom)
Bolt carrier area / front of carrier (where the bolt enters): 0.9470"
Ramp length: 3.2510"
All measurements were in inches.
I don't know if this did any good, but that's what I got.
They were selling nickel-boron bolts in these teflon-coated bolt carriers for $459.00 each.