Something other then the stuff it was keyholing with. If it was keyholing with the Tula then something like Winchester Q3131 or XM-193 should work.
I could be just the ammo you were using.
I was shooting some handloads with a 50gr Remington HP that was keyholing but none of the other ammo I was using was doing it, so it was just a case of bad ammo.

