Fully supported chamber means that the chamber entirely supports the powder area of the cartride/casing, unsupported would mean that part of the powder area of the casing is exposed, and is generally not considered a good idea because the casing can expand in this area, weakening the chamber AND/OR cause a blowout of the chamber, or worse. Glock .40's are known for this they say, but tons of police departments have been using these pistols for years without problem. Most people never experience a problem if they keep the ammo below the +p/+p+ specs. Most of the time a unsupported chamber is done to help feeding issues in auto's. You results may vary!
-- O. Jeremy Miles
-- O. Jeremy Miles
