The following data was developed in a Weatherby Mk V Accumark rifle. It came from the factory with a stainless steel fluted barrel, 26 inches long and a muzzle break installed. It was stocked in a gray synthetic stock. We installed a Leupold 4.5 – 14 X scope on it using Leupold bases and rings.

We used the Federal 215 primer in Weatherby brass. All groups are 3 shots at 100 yards.

To those of you who are interested in this kind of cartridge, you might have a look at our data on the 300 Pegasus. We found very noticeable throat erosion in that rifle after only about 50 rounds! We decided to check the throat of this rifle after every few rounds fired, and see if we can notice any difference in the throat. All our bullets were molly coated.

We had to stop using WMR and H870 powders as we were experiencing hang fire on every round.

50 rounds fired – no noticeable throat erosion.

70 rounds fired – slight erosion is noticeable just at the beginning of the rifling. It extends for about 0.040 of an inch.

100 rounds fired – no noticeable increase from above.

125 rounds fired – erosion is very noticeable, and the eroded area seems to have increased slightly.