For shots inside of 100 yards, ...

Anyone have any firsthand experience with using 12-ga slugs (either rifled barrel or smooth bore) for big grizzly or brown bears?  I'd like to know if my .45-70 Gov't is the better option using 525 gr. Pile Drivers, or if the 12-ga slug is just as suitable.  Seems to me (I haven't run the math on sectional density) 1 3/8 oz. 12-ga slugs at 1,500 fps oughta work well on both brown bear shoulders.

I just finished reading Larry Kaniut’s second book on grizzly attacks, titled “More Grizzly Bear Tales”.  Of the two usages of 12-gauges he mentions, one was a point-blank 00-Buckshot in the face, from about 9 feet away, which killed the grizzly instantly – all the pellets went into the same hole, punching a quarter-sized hole into its head, right next to one eye.  The other was a 1-oz slug, fired broadside on a running animal, that went through the lungs, where the bear still ran for another 50 feet before dropping over dead.  That shot punched a 50-cent piece sized hole into the animal.

Brenneke makes a 1.5 oz,  3-in Magnum, 1,600 fps MV slug called the "Magnum Crush." I like that idea.

some of the vids on slugs in gel are pretty underwhelming.  45/70 hardcast ftw.

Yes, OP if you use slugs get a hardened one like Brennekke Black Magic Magnum if you have smoothbore. You dont want a soft slug that does 16in in gel.

Also its not like 45-70 430gr hardcast wont do the job well.

Id use the gun you like the most.

Brenneke slugs is what AK fish and game use, that's always been good enough for me.

Slugs. Lead shot is a No No. When I guided waterfowl hunters on the Alaska peninsula I carried slugs.

If you're using it for defense against bears then you either one might work fine.  

If you're a Non Alaskan and are planning to hunt Bear that means you'll need a guide.  If that's the case the guide may have minimum caliber requirements.  If this is the case I would talk with the Guide and find out what they want you using.  They may tell you need to go a different route.  

Personally if I only had those two to choose from it would be the 45-70 with a good hard cast load.  

Since those aren't my only choices I would choose neither and go with my 375 Ruger or a 338Win Mag.

I am sure a really hard slug would work well.  You don't need any expansion since they are making a .72 caliber hole in and out.  Brenneke's or federal makes a trueball load that is made for deep penetration.  Problem is most guns won't shoot those loads that accurately to work past 75 yards or so.  That would really limit your shots for hunting.  4570 should work to 150 yards or so.

These are what I use in my bear gun.  666 grain hard cast .70 caliber wadcutter.

If you only have a smoothbores, then black magic is what you want.