Even if the sabot "rifles" in the bore, there is still the problem of the sabot maintaining a firm grip on the bullet. As long as a normal bullet is used, it has a smooth surface contacting the sabot. So there is the problem of the soft sabot gripping and maintaining a grip on the bore's rifling at modern center fire velocities along with the problem of maintaining a fixed relationship between the sabot and bullet. In other words, there is an inherent problem getting the bullet to stabilize. The faster you send it out the muzzle and the tighter (faster) the bore rifling is, the worse the problem is .... in a sabotted round.
Seems like good way to send a bullet out ala smooth bore (or at best veerrry slow rifling). That could explain the accuracy problems.
The slower I loaded my .308 Accelerators (in a NEF Handi-Rifle), the more accurate they got ... to the point that I had a fairly accurate small critter load. But it wasn't as accurate as a good bolt action .22LR in the $200-230 price range.
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