Free: Contests & Raffles.
Nope, fully loaded they aren't very heavy at all. But, they are LOUD!!! I have a PMR30 and it has a very nasty sharp loud crack and I think the FN 5.7 is a little louder. Very fun gun to shoot and with those big magazines you can really go through the ammo fast but you'll want to use good hearing protection when you shoot it.
Would you consider this a good backpacker option? I know the logic behind a lightweight, high caliber revolver, but if I can get away with packing 20+ rifle rounds around in a semi-auto pistol at about the same weight and with the ability to reach out and touch something at 100 yards, I know what I would want strapped on my hip during archery season. I currently pack a compact 40 bersa thunder...and I can feel the weight.
The round is traveling pretty hot at 2100+fps. Is it a question of penetration?
If it's bears you are worried about, I do not think the Five Seven would be a good option.
The Glock 31 looks like a good option...better than my previous Plan B.