Where can you find a 6 round clip for browning twenty two caliber buck mark long rifle pistol?

There seems to be a misunderstanding in your question. The Browning Buck Mark is a .22 LR pistol, and it typically comes with a standard 10-round magazine. Additionally, the term "clip" is often used to refer to magazines for semi-automatic firearms, while "magazine" is the more accurate term for the device that stores and feeds ammunition.

If you are looking for a 6-round magazine for your Browning Buck Mark .22 LR pistol, you can check with the manufacturer or with reputable firearms retailers to see if they offer such a magazine or if it can be special ordered.