Cutting off spurs is very simple, and does not hurt your chickens at all. Spurs have an inner core, which is the live part, and an outer husk, which is the hard horn type material. When you trim the spur, you are cutting the outer husk. The trick is to not cut into the inner core, which can bleed. The first thing you will need to do is to immobilize your bird.
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AISI stands for the American Iron and Steel Institute. The are just in charge of the standards regarding steel shaped sections. Normally, a few companies use them to regulate what they can manufacture and just couple that with their structural design. I also found some useful stuff regarding the AISI standards on SkyCiv.