Austin & Halleck's demise was caused by the collapse of their inline market and had little to do with the primitive replica rifles. Their bolt action inline, while a handsome rifle, simply fell off the sales radar screen when new drop action and break action rifles came on the market. Several small companies including White, Gonic, and Austin & Halleck did not have the financial clout or sales market share to invest in development of more competitive inline updates. Even Ruger and Remington refused to invest in such research and development for no larger than sales were. Remington ended up forming a partnership with Traditions to market inlines under the Remington brand. All of these muzzleloaders were excellent percussion cap systems but did not adapt well to 209 primers.
The primitive replica market is very small compared to the inline market. It simply could not carry the company on its own.
Really the only American companies left are Thompson/Center (a primitive replica importer), Knight, CVA (an importer), and Traditions (an importer). Lyman (an importer) has a good competitive edge on replicas. Pedersoli (of Italy) is the strongest company with any foothold in replica muzzleloaders. Your best bet for a good primitive replica muzzleloader if you don't want a Pedersoli or Lyman or less expensive Traditions model, is to go to a small, independent who is building from kits in a semi-custom manner. Some of these guns are very good.
But ALL the action in the muzzleloader industry today is in inline sales. If a company doesnt' offer a good inline, they can't compete with Pedersoli or Lyman on the replica market. It is a tough business and without significant financial clout it is almost impossible to remain competitive in the current market.
And frankly, the Austin & Halleck primitive replicas were not as mechanically sound as the Pedersolis or the Lymans. The company couldn't compete anymore.