Just got off the phone with my buddy and he asked me what causes tumble, im new to muzzleloading so I have no idea, he was shooting a encore pro hunter (brand new) with 150grn pryonex ,and 200 grain slug. after 3rd shot it was tumbling and he stopped shooting it. any ideas?

Too much powder or too light of a bullet. I had the same problem with my .45 cal Knight with 225 grain bullets. I opted for a bigger bullet and it solved the problem.

Need a little more info mcorso. Specifically, what 200 grain bullet was he shooting? Is he sure it was designed for a 50 caliber bore? How tight was it to load?

He was shooting 3 pyronex pieces, totaling 150 grains, and shooting 200 grain shockwave, the ones with the blue wad and yellow tip. I shot the same set up ,he loaded them to me to site my encore magnum, worked great for me, so thats why im not understanding why it "tumbled" for him.

Tumbling is caused by a loss of stabilization or disruption of the bullet, while the bullet is in flight. What some believe is tumbling, often indicated by a keyhole or side way shape/hole on the paper target is many times, the target tears from the energy of the bullet.

So unless something was causing that Shockwave not to spin properly, I can't see how it tumbled. Now stabilization is effected by many things.. the amount of energy behind the bullet, the twist of the barrel in correlation to the projectile being shot, and possible deformities in either the bullet or the sabot.

Since it happened on the third shot, my first question would be, was he swabbing the barrel between shots? My next question is, has any other bullet done this to him? And last is, how old is the powder?

All I know is he bought the gun last year and got it out for the first time this weekend, im assuming since this is the 1st time he shot it, thats the only ammo he has shot.so he either bought it last yr,or recently. He let barrel cool in between shots,

If he is getting good accuracy it may not be tumbling at all. Could be an odd tear in the target as mentioned above. If he is getting all odd shaped holes and poor accuracy, they may be tumbling.

First, I'd back off to 100 grains of powder. If he wants to extend his range, he could go to loose powder charges up to say 120 gr. For normal ranges like within 100 yds, I'd go with 100 gr.

If that doesn't cure it, I'd switch bullets. Of course, this all assumes the barrel is in good shape.

Right, But I have a encore magnum, and he has a encore pro hunter, arnt they pretty much the same gun? so we should be able to shoot the same thing, Mine is shooting great on that set up, hitting bulls at 100 yards, At 50 yards he was barely hitting the back stop it was 4ftx4ft. and bullets were all over the place, and sideways through the board, and we had rifle seated on sandbags, I told him to give it a good cleaning, and try it again, then we can try new ammo.

I was going to suggest the assumption of tumbling was mistaken, but what you describe -- sideways profile and 4X4ft pattern -- is perfectly consistent with what you expect when tumbing (tumbling bullets DON'T shoot 3-4" groups at 100 yds).

This is HIGHLY unusual. I have never seen anything that dramatic with typical ML bullets. The only explanation (other than a terribly misbalanced batch of bullets and I've never heard of that) is that for some reason the sabots are not engaging the rifling and giving proper spin.

The 200SW is one of the longer-for-caliber bullets, but certainly not on the fringe of risking tumble under any normal conditions.

Does it load really loose? If so try a tighter sabot or step up to a .44 or .45 bullet in a tighter sabot.

Something is VERY wrong here.

I agree, thats why he stopped shooting it, just doesnt add up, will keep you guys posted, gonna get it all cleaned up, and see what it does, i wish i had took pictures. thanks for all the input.