Does anyone know where I can find gun holders for an API Grand Slam Magnum Extreme?

I have tried Bass Pro Shop (didn't fit). I tried Cabela's (didn't fit). The problem is that the Magnum has larger square tubing than the "regular" API Grand Slam. Each time the person taking the order told me that they were sure the gun holders listed would fit. The picutre and description on the Bass Pro Shop web site even said it was for the Magnum, and it cost more...didn't fit.

Thanks