Those Precisions may be too loose for you older Knight ML. The former produced Bighorns were slightly wider bores back then. Knight has since gone to a smaller diameter bore.

I would suggest you purchase the 375 gr Buffalo S.S.B instead. They now come with a thicker sabot. Should make a nice fit for your rifle -- plus that S.S.B.bullet is stillused by a couple ofML bookauthors for elk-hunting today & has a pretty darn good co-efficiency.

The Precision bullets are fine & the Elite is similar to the S.S.B. But you may need to swap the Precision plastic sabot for a MMP HPH-12 for a tighter fit.

http://www.shootnhunt.com/catalog/JM/black_powder/bullets_balls_sabots/buffalo_bullet_co/0512935.html

Here's some info on the bullet. The S.S.B discussion is about half-way down the page. Good interview by Wakeman there.

http://www.chuckhawks.com/buffalo_bullet_king.htm