You mean 50 lbs for the airline?
Wear your hunting boots while you fly instead of packing them, same with your heaviest pants. Put your outer hunting jacket over your arm and carry it on the plane, even if it's hot outside.
Put heavy, valuable stuff like binoculars and spotting scope in your carry-on bag. Same with any book or other small, heavy item.
In other words, let your carry-on weigh 30 lbs if you have to. You get a carry-on bag and a "personal item" which they are usually pretty lenient about. For me, that's a soft-sided briefcase that will hold quite a bit.
See if you can fit some small stuff like your flashlight, headlamp and rangefinder into your gun case.
Buy batteries and food after you land.
Don't pack too much clothing.
Keep your toiletries small - I use the WalMart travel size stuff or better yet, a small bottle of concentrated soap from REI.
Don't bring both a tripod and shooting sticks. Just shoot off your tripod.