absolutely not.
i mean, shoot aa 5744 in any muzzleloader designed for smokeless powder, but NOT for barrels designed for BP/BP subs.
seriously.. lyman states that 100 grains of 777 under a 300 grain saboted projectile generates approximately 23,000 psi.
44 grains of 5744 under the same bullet will generate in the neighborhood of 37-39,000 psi.
not the same, is it.
try and reduce it down? not happening.. even if you could get the pressure down, your accuracy would suck. 40 grains is savage's recommended MINIMUM for 5744. and 40 grains shoots about 4"+ groups out of my savage. 42 grains shoots 1.5", and 42.5 gets right around MOA. 43 grains goes back to 2.5-3" in my gun.
the steel in a BP/BP sub barrel IS NOT rated for the pressures of smokeless powder. i wouldn't do business with the dealer that told you that.
in the bigger picture, savage is not the only player in the game.. you can get smokeless powder barrels for both H&R's and Encores. personally, i think that the savage is the strongest action, with the most features (dual pillar bedded, dual exhaust ports on the bolt shroud, free floated barrel, recoil lug) but to each his own. if you try smokeless muzzleloading, be ready to spend some time at the range. a grain or two makes a difference in the load, sometimes a big difference. pretty much like reloading for centerfire rifles. furthermore, you need to consider the heat you generate, and the sabot you use. no longer do you use whatever sabot is supplied with your bullets. toss those out and order directly from a reputable sabot make, such as MMP. and be prepared to try a number of sabots. a lot of guys get lucky and find loads right off, but some don't.
lastly, i would mention that the benefits of smokeless are cleanliness and reduced recoil. can you get 2500 fps+ out of your savage? sure, sometimes as much as 2700 fps. but those loads come at the cost of high recoil and potentially blown sabots, which is fine if its one out of ten on the bench, but that won't do (for me) for hunting. realistically, you can comfortably shoot 2200-2400 fps. and you know what? you can get 2000 from 100 grains of 777 and a 250 grain bullet. how much more distance does 200-400 fps get you? 25 yards in 6" point blank range, maybe? (175 yards vs. 200) little less wind drift?
there's only so much you can do with a .45 caliber bullet; speed cannot compensate for everything.
but oh.. it is so sweet to spend a day at the range and put the gun away until season starts, without cleaning it..