$1300 can build you a 45cal smokeless that will send a 275gr bullet down range at over 2500fps with ease and there is no need for a sabot.
Why would you want a form 4473 smoker for that price when you can build one that can use a huge variety of powders AND has a match grade custom barrel?
Pacnor, Brux or McGowen barrels will typically shoot circles around a factory Rem barrel.
If you already have a Rem700 CF, Stevens 200 or a Savage 11 SA the cost is little more than the barrel and bolt head. You could even convert one to a Krieger barrel with a LRMP module ignition for about that price at Hankins rifle. It even retains the factory bolt head if its based on the 308Win case.
How does a 275gr bullet at 3000fps sound vs that pellet burner?
Or you can buy a new in box smokeless already built by Savage for $1379.00...
http://www.gunsinternational.com/detail.cfm?gun_id=100479569&pop_up=1Savage99F358