SiG P239 9x19mm: Is this 7+1 or 8+1?

SiG P239: .40s&W: Is this 6+1 or 7+1?

Do both of these handguns have supported chambers?

Ty.

P239 9mm 8+1
P239 .40    7+1

Generally yes.  Fully supported not likely in an auto-loading pistol.  This refers to the amount of brass that is not covered by the chamber.  This area is usually going to be located near the feed ramp.  With the barrel completely out of the firearm, if you place a live round in the chamber, any brass that is showing besides the rim is considered to be unsupported.   Some chambers support more than others.  This usually isn't a major deal but in case of a rupture the gases and unburned powders are directed downward back into the magazine area.  

Quoted: SiG P239 9x19mm: Is this 7+1 or 8+1?

8+1 as sigarmvin already mentioned

a 10rd factory mag is also available to make it 10+1.  the mag extends down from the grip about an 1"  

i just acquired a 9mm 239 a few wks ago...nice little pistol!