The following data was developed in a HEYM Express bolt action rifle. It has a 24-inch barrel. The weight of the rifle was 12.8 pounds. It has open sights and the receiver is drilled and tapped for scope mounts.

We could not help comparing this rifle to the A-Square Hannibal in 577 Tyrannosaur. Which we have here. Both are very large, heavy rifles. Both are extremely specialized, but not surprisingly, the Heym 600 Nitro Express handles a lot better than the A-Square 577 Tyrannosaur. This is purely a personal preference, but all shooters that have handled these rifles prefer the stock on the Heym.

We do not have any facility for checking the pressure of our ammunition. None of the loads fired showed any signs of excessive pressure. But please bear in mind that this a modern bolt action rifle, which would probably handle higher pressure much better than any old double rifle. Also in a double, one of the main concerns is "regulating" both barrels to shoot to the same point of impact. In the past we have used IMR3031 for double rifles such as 470 Nitro Express. With this powder we were able to duplicate the velocity of some original factory loads and get them to regulate well.

We used the Barnes and Woodleigh 900-grain solid bullets and the Federal 215 primer in all the following loads. The brass was made by B.E.L.L. in 1986. The rim on the cases was too large in diameter for this rifle. Original rim diameter for a 600 Nitro Express is 0.805" Apparently this was too large to go through the front part of the receiver into the barrel! We had to turn the rims down to 0.777".