What should be the spread of regulated fx royale 500 .25?

[mubhaur]

I have just regulated two fx royale 500 .25. Both running at 900 fps with 25 grain JSB.

One gun is giving spread of 10 fps while other is giving the spread of 20 fps. Unable to understand the reason.

Any suggestions?

Regulators of both are set at around 145 bars.

Regards,

Umair Bhaur