A modern load for the .45/70 pushes a 400 grain bullet at what...about 1900 fps...
lets see what buffalo bore has to offer :
Item 8A: 430 gr. L.B.T.- L.F.N. - G.C. (1925 fps / M.E. 3537 ft. lbs.)
(Big game up to 2500 lbs. - Penetrator Load) Per Box of 20
$46.19
Order Now!
http://www.buffalobore.com/ammunition/default.htm#4570
no one would call a modern load for the .45/70 inadequate for short to medium range elk hunting.....
lets see what a win supreme sabot 12 ga load is like....Lets use the Platinum tip because we want it to stay together and penetrate....
Platinum Tip™ Hollow Point Slug
400 Gr. OZ #SABOT SLUG
Muzzle velocity 1700fps energy 2566ft.lbs.
Still pretty significant in my view.
I could not find the older winchester partition gold 385 gr 12 ga at 1900fps which has roughly 3000ft.lbs at the muzzle.
For short range the 12 ga ( with the proper slug, and accurate gun ) should do well.
edit: add the remington slug load for comparision:
Index No. Gauge Shell Length Slug Wt. Velocity
Premier® Core-Lokt® Ultra Bonded Sabot Slugs
PR12CLU 12 2 3/4" 385-gr. 1900fps
description from the remington page: The ultimate in shotgun sabot slugs. Ultra-high velocities deliver devastating on-game performance and the tightest groups —1.8" — of any shotgun slug with ultra-flat trajectories. Remington® patented spiral nose cuts ensure consistent 2x expansion over a wide range of terminal velocities, while the sleek, ogive nose delivers high down-range energy retention. The 385-grain bonded bullet yields near 100% weight retention. Flattest shooting slug in existence — 10% better than the nearest competition. Designed for use in fully rifled barrels only. In response to the overwhelming success of the 12-gauge load, this year we’re offering a new 20-gauge, 260-grain load for those who prefer the low recoil of a smaller gauge slug.
That will drop an elk at short range!!!!!!