S&W 40 +P seems to be an uncommon round. I never really considered it before but you prompted me to look it up. It looks like Buffalo Bore, CoreBon and Triton are the only ones that I found available. Do you have any others. Also according what I've read, they're not recommended in a Glock. Not being sure myself, I'gm wonderin if they're safe in the Sigma. I copied the below statement from Buffalo Bore's website.
SAFETY NOTICE
"Some pistols chambered for the 40 S&W cartridge may not provide complete support of the case head. If this condition exists, normal pressure loads such as those shown here can cause the case wall to bulge or rupture at the unsupported point. Contact your firearm manufacturer to determine if your pistol completely supports the case head, or ask a gunsmith to inspect your pistol before using it with ANY ammunition. It is the gun owners responsibility to know his firearm and its capabilities and limitations."
40 S&W WARNING
"This data is intended for use in firearms which fully support the cartridge in the chamber. Use of this data in firearms which do not fully support the cartridge may result in bulged cases, ruptured cases, case head separation, or other conditions which may result in damage to the firearm and/or result in injury or death of the shooter or bystanders."
Glock happens to chamber their 40 S&W pistols without a fully supported chamber and both of those above safety notices are likely aimed at Glock. I know of no other 40 S&W handguns being sold in the US that don't have fully supported chambers. If you really want to shoot our 40S&W ammo in your Glock, have an after market barrel that uses a supported chamber, dropped into it. This is a fairly common practice and will give you the safety margin needed to fire our ammo in your Glock. It will also likely give you more velocity than the factory Glock barrel. I personally own two Glock Model 23's. Both of mine are going to get after market barrels dropped in so that I can use this excellent ammo in them.
(copied from Buffalo Bore's website)