When they show up they ate sold quickly. All I see are 9mm uppers for sale.

Why start 3 different threads on the same subject (Sig 320) only minutes apart? Start one thread, then add to it if you have more issues to discuss.

How many times does this have to be explained to people...

I actually didn't know they offered a .40upper. But its just a guess since sig shows no .40S&W guns or conversion kits on the current website that's the issue. Heck at least on the webform search they don't even show the caliber! that maybe they are in short supply like all things sig out of production. But maybe its something else...

Ebay has been full of them; I'm sure they're all over.

I think a lot of the .40 uppers or parts came on the market because people able to purchase .40 pistols for less, and then parted them out, or used just the FCU or lower parts for their project.

9mm seems far more popular.

I have a P320 carry in .357 Sig, and recently picked up a .40 barrel for it, new, for about half of what Sig had been asking. 9mm barrels are in demand. .40, not so much.

I own an original version of the P250, with .40S&W and .357 Sig barrels and the necessary recoil spring. Can I replace the Compact barrel on my P320 with these?

If I had to hazard a guess people are buying them in order to use the ammo available on their area or they are buying them in fear of a future ban.

Since Mason Lane won USPSA Nationals Limited with a P320 and a Gray Guns 40 slide I suspect many are buying the 40 slides up. I usually shoot 9mm in production, now I can shoot 40 limited. doing just that tomorrow USPSA match 40 limited.