PPosey,
Only for us belts and suspenders guys there is a way to seal the necks. Get a small can of Ortho tree pruning tar and some "Q" tips. Put a thin dab around the side of the bullet at the base. Seat the bullet, crimp (as appropriate), and wipe off any excess. That is basically what the military (the original belts and suspenders folks) does with a lot of their ammo. We have to remove the tar from the bases of pulled GI tracer bullets before we load them up for our annual New Years Eve "Light up the Night" machine gun shoot.
I got in the habit of sealing ammunition when I lived up in Alaska. I know many people who have hunted up there for decades without sealing ammunition who have never had a problem. A friend of mine was float fishing the Alagnak (Branch) river near King Salmon in 1992. One very windy evening (still twilight) a brown bear took exception to their raft and tent fly. After about fifteen minutes of seeing his gear (and feeling his nerves) get shredded Allen decided to fire his shotgun into the dirt to scare "Mr. Crabass" away. "Click". Shuck, slam "Click". Etc. Several days of rain had worked their magic on his shells. The bear lost interest and wandered off after a while. My friend felt like Linus minus his security blanket. Ever since I have sealed any ammunition that I load for use in those types of climates. I now carry a worked over stainless 45-70 "Guide Gun" with some warmish 420 grain hard cast loads for my own "Dances with Bears" deals when I am fishing up north. Those shotshell loads were designed for going through deer (and human) rib cages, not bear skulls or bear shoulders.
I've been "bluff" (false) charged once. Usually the bear and I high tail it in opposite directions, but those creatures are very unpredictable. If you fish the streams during the salmon runs you will run into bears. I used to wear a Rolex watch so someone would hunt down and shoot the bear that might eat me, but I don't really care about that as I've gotten older. I traded the watch for a couple guns.
JCN
Ross Seyfried says that it isn't necessary to seal ammunition. He's probably right, but I do it anyway.

JCN,,,

why do you remove the tar residue????

I wonder if pressures will go up with sealing? I was in Kantishna and Denali Park for awile, Nothing like a chomping sound in the head high willows to raise the pucker factor ehhhhhhh????

On the pulled tracers I buy the residual tar is stuck to the bullet in little chunks. My personal neuroses are manifested in my being too fastidious when I reload. I don't worry about sealing my loaded tracer ammo. As soon as I have some loaded I zip over to a friends house and we link it up (every 5th round), head up onto BLM land, and light up the night.
I don't know about the pressure. If Santa brings me a pressure trace system this year that would be a good experiment.
Nothing quite like walking along a stream on a bear trail and finding a manhole cover sized pile of steaming bear shit to get the old blood pressure up. I tried to stay off the bear trails and just bushwack through the alders once. That works great if you need some exercise and don't have anywhere you need to be in the next week or so.
JCN

asoooooo

yep