>>1402265The only time you could possibly harm your reel is if you are using a super stiff saltwater rod with a freshwater reel, the drag on the reel is set to be as tight as possible, and you are using 50lbs+ fishing line and you get snagged on a rock or the line gets in a boat prop or you hook a shark/5 feet long flathead catfish. Then all the force applied to the line will go directly to your reel. There's a chance it would strip whatever drag mechanism it has or perhaps twist something off like rounding some gear teeth. But, even in that situation all you'd need to do is release the drag enough to properly account for such a situation and nothing would be a problem unless you perhaps ran out of line.
Basically, no it won't harm your equipment if you use the equipment properly regardless of the mismatched gear.
