Hello stangman645,
I'm new to this myself but I bought an old refurbished HEAVY DUTY Brother sewing machine for sewing leather and found it's good for leather up to about 4 oz.The fellow I bought it from said it will sew 2 thicknesses of 10 oz leather,which it does but this is when you have the machine going full pin.It's very hard to control and I believe it's hard on the little motor. After doing more reseach, I found out that you want a commercial /heavy duty leather sewing machine with a servo motor which has the power and control to handle heavy leather. I like the info on the cobra machines that have a motor, and I also like the tippman "BOSS" that is handpowered which would be handy, especially up here in the bush where we don't have power. Anyway, check them out ,see what you think, hope this helps and take care.