[Mike Irwin]

"I recall a mixed review on it as the Brit ammo was poor to start with. I don't think you could hit anything past 500 yards with their Sabot."

Early issues with the sabot being horribly inaccurate were traced to the outlet dimensions on the original version of the muzzle brake. Which is funny, considering that the original version of the gun, the Mk II, didn't have a muzzle brake. The brake was only introduced WITH the introduction of the APDS round and Fireflys already in service were refitted with the brake.

Once the brake was redesigned the APDS ammo became a LOT more accurate, and a specialized maintenance kit was developed that allowed the muzzle brake to be redimensioned in the field.

From what I've heard, it was basically a clamp-over guide for a big bore/chamfering cutter.

The APDS ammo was never quite as accurate as solid rounds because the rifling spin could cause issues with the sabot separating cleanly, but once the brakes were redimensioned it was more than accurate enough to get hits at 1,000+ meters.

And, given its huge increase in performance (2+ inches more penetration at 1,000 meters) over the standard armor piercing ballistic capped rounds, crews were happy for that trade off.