I too have a 700 MLS with a weather shroud. I close my bolt and put a line with a pencil on the bolt in the receiver then install the shroud so the hole is lined up with the pencil line (it should be just above the receiver in the closed position to allow smoke to escape) If it is really wet, I will replace the primer often and dry the nipple. Carry my capper in a sealed ziploc. Another thing I found that works well is a wool sock over the breech area if stand hunting, replace as it becomes saturated.

If it is wet, snow, high humidity, etc I always tape the barrel with electrical tape, it does nothing to the POI or Ballistics. The gas will blow the tape before the bullet. I took 3 animals with the taped barrel, no problem the bullet went where it was suppose to.

I install the breech plug & nipple with teflon tape (pink plumber style) to prevent moisture from the breech area.

Whatever you do at the end of the day fire it and clean it very well when it is damp outside.

Hey, all..wanted to come back and give you a report. Great advice here. I wound up sealing my cap to the nipple with findernail polish, then wrapping the receiver with cling wrap. I then used camo tape to cover the cling wrap (it was too shiney and reflective for my tastes). Finally, I put a piece of cling wrap over the muzzle and help it on with a rubber band. It worked great. It rained for a solid 12 hours on opening day here and was humid as heck. I hunted out in the pouring rain all day...didnt see the buck I'm after but I tried it when I got back to camp that night and it fired perfectly. The cling wrap on the muzzel was a bit tough to keep on, so I'm liking the electrical tape idea for next time. Also, my cousin uses a T/C side lock so he just sealed the nipple with nail polish and put cling wrap over the muzzel. When he test-fired it failed! He replaced the cap it fired. Side-lockers ought to keep spare caps and nail polish in a ziplock and change every couple of hours in the rain, I think. Thanks everybody!