While caution with higher pressure loads in older guns is a good thing, it sometimes gets taken too far. Its wise to use shells loaded to the pressures the gun was designed to handle. If your sterlingworth has fluid steel barrels with nomial bore diameters and no external thinning then it should have sufficient barrel wall thickness to handle moderate pressure nitro loads. It was designed for such loads. Personally I would shoot the F2s in such a gun without concern about damage from a sub 10,000 psi service pressure. However, if the gun is 6.25 lbs or less, then you should be prepared for handling a bit of recoil from those F2s. With 30" barrels, I suspect your sterlingworth weighs a bit over 6.25 lbs. So recoil may not be an issue for you.
