When we ran our home business (airplane model kits) we used PayPal to process all of our orders. Mainly it was for my protection because I did not want to have access to the buyers' credit card info. I also used paypal to pay for business items to various vendors.
We did take checks or MO's, but, customers did not like that we would wait for the check/MO to clear before processing the order. I took a dislike to MO's after talking to the local postmaster about forged MO's and how common they were.
I ALWAYS use Paypal when it is an option to pay for something online, including gun parts and supplies.
Bottom line is I've used Paypal tens of thousands of times, including gun stuff, and had not one issue with them.