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I've got an older Marlin 336 30-30 that I use for Whitetail Deer hunting. I took it to the range the other day. At 50 yards my first three rounds were in the bulls-eye. I loaded three more rounds and squeezed them off and all three of these hit about 1 1/2" low. I loaded three more and let-em fly. These were about 3.5" low at 50 yards!!! I went back to the range a few days later and with a cool barrel I was back in the center. Now I realize that during the typical deer hunting scenario, only one round is used, not nine, but can anyone shed some light on why this is happening and can it be corrected?

I would guess that the barrel is bearing upon something that affects the point of impact as the barrel heats up.

The need to fire so many rounds at one time comes up so seldom that I would just remember and take "Kentucky windage" if necessary, rather than try to fix it.

I once had a Marlin 1895G that would do the same thing, but I never had reason to fire more than one or two rounds at a whack in the field with it, so I just made sure to let the barrel cool thoroughly between shots at the shooting range.

Taking a second gun along to the range is a good way to shoot without having to wait around a lot for a gun to cool. After I shoot, I leave the action open to air out the barrel while I shoot something else a time or two, at a different place on the target.

Shooting a barrel hot should be avoided if possible. All of the bad things happen a lot faster, then. ( Wear, fouling, erosion etc.. )

I'm not a levergun expert, but I'm a fairly good troubleshooter.

My best guess, based on the 22-caliber Henry guns I have and the single inherited 30-30 ... barrel heats up, gets marginally longer, while magazine tube doesn't. As they're attached front & rear, stresses on the barrel change as it heats. I bet your front attachment isn't capable of sliding like a figure-8 barrel band.

Just a guess.

BFD has described the problem very well. Uneven heating is causing one component to pull on the other altering the point of impact.

R,
Bullseye

Thanks to all who replied. I guess I just need to use the "aim small, miss small" method when hunting to insure a quick and humane kill shot on the first shot.

I am not familiar with this particular rifle but I'd take the hand guard off to see where on the inside the barrel may be rubbing due to expansion when it gets hot. If it's visibly darker at a particular spot simply sand down that spot and shoot again after re-assembly. Simple fix that I recommend you execute, there's no good reason not to be able to attain the same POI each and every time.

Good luck!