The original .44 Carbines used a gas piston to actuate a hidden, long, operating rod that has cams/slots in the rear end of it's config that turns the bolt in/out of battery.
The 99/44 Deerfield is basically a Mini-14 on steriods, with it's operating rod atop the barrel side - and would be exposed, possibly catching the user's fingers, if not for the handguard.
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