I use a CVA Eclipse 1 in 23 twist. Of couse it has taken me all summer to find this load combo, lots of spare bullets left..

Why I asked my first question is, last night I shot a buck at 70 yards and the buck was knocked off its feet onto its back and laid there for about 30 seconds, got up and ran off before I could reload, when I got to where the buck was I started tracking, there was no blood, hair, nothing. I started to follow his tracks until he stopped running, 100 yrds or so, then I started a grid search thru the brush for another 300 to 400 yrds, nothing. Went back this morning and searched for 3 more hours nothing.
Any ideas on what could of happened? This is my first year to use a muzzleloader, I know what to expect from my bow and 270.
please help...