IMHO Any new gun should be fired from a rest first.
You still don't know if it's the gun or you that is the problem.
If it shoots good from a rest, you just need more practice.
If not....
I had a Charles Daily ECS ( the 3 1/2" barrel) that was an absolute tack driver with ball ammo.
But, it would jam on hollow points every time.
I sold it and bought a Para LTC, but the point is, it IS possible to have an accurate short barreled 45.