I'm new to USPSA & IDPA and in the process of weeding my way through the USPSA & IDPA rulebooks and I just had a few questions regarding whether certain firearms are legal or not and I'm getting a bit tripped up trying to figure it out as I'm interested in the Carry Optics division.

Are the following handguns legal in IDPA Carry Optics:

1) CZ Shadow 2 (using an aftermarket slide from Primary Machine to bring the weight under 45 Ounces)
2) STI Staccato P Duo
3) Sig P320 X5 Legion (With the magwell detached).
4) Sig P226 Legion SAO

Same question, but for USPSA Carry Optics:

1) CZ Shadow 2 (using an aftermarket slide from Primary Machine to bring the weight under 45 Ounces)
2) STI Staccato P Duo
3) Sig P320 X5 Legion (With the magwell detached).
4) Sig P226 Legion SAO (I'm not sure, but I'm guessing that Carry Optics still has to use the USPSA Production Gun List?  If so, I see there is a note that no Sig SAO versions are approved.  I'm just not sure if that is only for Production Division or that applies to Carry Optics as well.

Also, just a generic question.  Are Extended Magazines allowed (using a Taran Tactical Extended Base Plate) in USPSA Carry Optics and/or IDPA Carry Optics?

Thanks for the help and advice :)

No on the sti and the sig 226 Single Action Only
Production and carry optics guns must ether have a double action first pull or a safe action like the glock
Single action guns are legal in limited or L10

Just wanted to say thanks for chiming in.  I'm in the process of learning the rules and so it can be a bit tricky figuring what is and isn't legal.  Thank you :)

Sucks you can't use the magwell with the Legion. It's really nice with the magwell.

CO division in IDPA is based on ESP division.  Basically take a ESP gun and put a dot on the slide.   Advantages here over USPSA are that you are allowed a magwell and single action only firearms.  Disadvantages here are every pistol in IDPA is limited to 10 rounds in the mags, and the weight limit is challenging to meet with some guns.

CO in USPSA is based on Production division.  Must be a gun from the production approved list, with a dot on the slide.  Production is 10 rounds only, while CO is whatever you can fit in a 140mm magazine. (23+/-)   A recent change in USPSA Production and CO is the 59oz weight limit for any make/model.  Aftermarket slides are allowed now as well.    Advantage here over IDPA is the round capacity, weight limit, less restrictive holster placement rules,  and well none of the weird IDPA rule stuff.   Disadvantages here are you can't use a SAO gun, and you can't have a magwell.

ETA:   shoot either the shadow 2 or the x5 in USPSA CO with extended mags.