Hi guys, Im new to cast bullet loading in rifles. I just loaded up some 174grGC .312 beartooth bullets in my No1 Mk 3 lee enfield. Powder charge was 26gr of Accurate arms 5744. PERFORMANCE WAS HORRIBLE. the bullets were keyholing when they hit the target, if and when they even hit the target. I have a few ideas why this happened, but would like inputs also. As stated previously, the bullets are .312, My bore mikes out to .311ish with my calipers, its kind of hard to check because of 5 groove rifling. This rifle shoots jacketed bullets of .311 very accurate so i know the rifle isnt at fault. My first idea is that I used a lee loader to load this ammo. When i seated the bullets I didnt have much of a problem starting the bullets, but I wonder if the gas check and base might have been disturbed when seated. This loader does not have a provision for belling the case neck and I am thinking this is a very possible problem. My secong idea is that even though the rifling is very clean and sharp on this rifle, the chamber throat is very long, so long in fact, that the cast bullet i am using isnt long enough to seat far enough out to engage the rifling. I have read that seating the bullet out to engage the rifling helps cast rifle loads. So I am thinking that excessive bullet jump might also be a problem. Would appreciate any inputs, thanks