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If your 527 is reasonably young (newer style trigger shape) it will most likely be 1:9. If it is an older model it could be 1:12 or 1:9.
I have an old 527 Varmint model (H&S Kevlar stock) in 1:9....

My first thought was your twist not stabilizing them but twist problems usually show up with key holing. And sometimes not classic full on keyholes but just slight tilting which you can see with...

What sort of velocities did you get?
Are all the holes completely round?
Maybe try a different projectile.

What sort of groups were you getting with factory ammo?