embroidering on gun case

I am embroidering names on gun cases and it is very thick. I am wondering what size needle to use on something this thick. And, any other tips for thick material would be welcome. Thanks

Location: 
United States

IMO the 80/12 Teflon Coated Needle from Organ is an absolutely fantastic thick item needle. Great on all hats, caps, heavy cordura, duck and many others. Can't be beat and you don't need any lubricant to assist in the sewing. :D :D