I race motorcycles and have checked-in just about everything legally imaginable as my checked luggage, domestic and all over the world. You should see what auto racing teams check-in on their flights. "If it fits, (and isn't a prohibited item), it ships." You'll be fine. Just remember luggage handlers are even less careful than USPS so if it's fragile make sure it can be dropped from a cargo door without breaking.

Everything gets x-rayed and sniffed for explosives. If what you're shipping doesn't trigger any concern as a prohibited item they won't open it but always assume they will and make it as easy for them as possible. Also, non-standard luggage items often have to be dropped at the oversize drop so give yourself an extra 10-15 minutes.