IPSC Action Air Handgun Divisions - What's the difference?

So what are the differences between all the different handgun divisions in IPSC Action Air?

On a high level, the idea is to keep similar types of guns within a same competition level for fairness, from the gun performance to capacity you are allowed to load.

Here's a breakdown...

Production

This division is the run-of-the-mill division, where most duty type, factory handguns fall in this category. Most of these guns are double-action or striker fired guns, single-action only guns are not allowed. The spirit behind this division that anyone can just buy a gun off the shelf and run it in a match, or duty/law-enforcement can use their carry service firearm to compete. Certain competition modified factory guns also fall in this category. IPSC maintains a list of approved models, that can be used in this division.

In Production, there is a round count limit of 15 BBs in the magazine.

Notable models: CZ Shadow 2, Glock 17/19/45, SIG P226, SIG P320 M17/M18/X-Series

Production Optics

Just like Production, but evolved. For the most part rules are identical to Production, but with a slide-mounted red dot optic.

Just like production, magazine capacity is limited to 15.

Notable models: CZ Shadow 2 Optic-Ready, Glock 17/19/45 MOS, SIG P320 RXP

Standard

The original race-gun division, and where the airsoft handgun you see everyone, the Tokyo Marui Hi-Capa, evolved from. This became a division for the most part when the double-stack 1911 appeared which proved to be a big advantage over the single-stack. Most competition modifications like thumb rests, extended magazine releases, magwells are allowed. The only limitation here is that it must fit inside a dimensions box with the lid closed, and compensators, red dots are both not allowed.

Standard limits magazine capacity to 18.

Notable models: Tokyo Marui Hi-Capa / Staccato XL 2011, CZ TS2

Classic

Like the name suggests, this division harks back to the origins of IPSC, In this division, all guns must have the contour, look and feel of the original Browning-designed Government model 1911, down to the capacity, so you are only allowed to load 10.

Certain modifications like magwells, ambidextrous safties, extended magazine releases are allowed, but it must still resemble a "Classic" 1911, so no full dust cover rails, or drilled, lightened slides.

Notable models: Colt 1911, MEU, Kimber 1911

Open

Think of this as the "formula 1" division. Full-blown built, thoroughbred race pistols that pretty much has speed and accuracy in mind. Pretty much any modification is allowed: compensators (not much use in airsoft, but it allows you to install a long inner barrel for more accuracy), racking handles, giant magwells, thumbrests. In the pursuit of speed and accuracy, your budget is your limit.

And the other limit here is magazine capacity is limited to 28.

Notable models: Tokyo Marui Hi-Capa with open slide kit from Airsoft Masterpiece/Gunsmith Bros

For more details, refer to the Appendix D of the IPSC Action Air rule book: https://drive.google.com/file/d/19VYSZU3KO3XLfeGsSIL8ynckbLhYvV_O/view