So, I acquired a bit of IMR 8133 to play with, and decided to try this newer slow burner in my Vanguard II, chambered in 257 Weatherby.
There is a singular lack of information for this Enduron powder. However, the burn rate charts place it right near Retumbo and Vihtavuori
N570.
With that in mind, I loaded some rounds with the 120 Partition. Fed 215M primers in Weatherby brass. I started at 69 grains, and loaded
69, 70, 71 and 72 grains behind that big Partition. Headed to the range with my chronograph.
The 69 grain charge was milder, with lots of primer radius remaining Graph said just over 3130. 70 grains was a bit faster [c.3195] and
primers still indicated moderate pressures. At 71 grains, the graph said 3250, and the primers were a bit flatter....3-shot group at 100M
measured .78" 72 grains proved to be the winner. Primers till looked good, chrony said [5 shots] 3310, 3305, 3299, 3297, 3308, avg - 3303
at 15 feet, so an honest 3315 fps, and the best part. 3 shot groups just shades ½ "
I do believe I have a hunting load for this Weatherby. Next tests will be the 100 and 120 A-Frames. I'm liking the results with this new
slow-burner. Dave.

There is a singular lack of information for this Enduron powder. However, the burn rate charts place it right near Retumbo and Vihtavuori
N570.
With that in mind, I loaded some rounds with the 120 Partition. Fed 215M primers in Weatherby brass. I started at 69 grains, and loaded
69, 70, 71 and 72 grains behind that big Partition. Headed to the range with my chronograph.
The 69 grain charge was milder, with lots of primer radius remaining Graph said just over 3130. 70 grains was a bit faster [c.3195] and
primers still indicated moderate pressures. At 71 grains, the graph said 3250, and the primers were a bit flatter....3-shot group at 100M
measured .78" 72 grains proved to be the winner. Primers till looked good, chrony said [5 shots] 3310, 3305, 3299, 3297, 3308, avg - 3303
at 15 feet, so an honest 3315 fps, and the best part. 3 shot groups just shades ½ "
I do believe I have a hunting load for this Weatherby. Next tests will be the 100 and 120 A-Frames. I'm liking the results with this new
slow-burner. Dave.

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