300 WSM RL16 starting load

Laguna Freak

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I recently had my 2001 Win M70 300 WSM blue-printed and rebarreled with a Brux 26” #3 contour. In my factory 24” barrel 62.5 gr RL16 x WLRM primer pushing 180 Scirocco II @ 2850 ish was a low end load. I have shot 64.5 gr with no pressure signs in the factory barrel. Alliant has no data for this combo.

Does anyone have experience to indicate I should start lower than 62.5 gr on rebarrel load development?
 
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Laguna Freak

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This is my short action Rhett. Still waiting on Bartlein so I can do the long action build.

So, 3.05” max COAL. Starting CBTO = 2.29” based on these bullets liking 0.060” jump from factory chamber. I had the Brux throat reamed to allow for 0.030” erosion before I have to set the barrel back.
 

MSURunner

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GRT suggests that you should have gotten about 2932 fps with your factory barrel, so I would guess that it had a slightly looser bore. It also suggests that you should be able to go up to 64 gr before exceeding SAMMI spec on pressure, so I would guess that the 64.5 gr would be accurate as far as indicating pressure signs (which would tell me that the pressure model is at least close, especially noting the slower speed on the previous load). It says that you should be fine with your 62.5 gr start, putting your expected velocity at 2990 fps. If you're substantially over 3K, I would say that you will want to back it off. It looks like 3050 will be about your max with that combo, which again happens at 64 gr.
 

Laguna Freak

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South Central Texas, just north of the Wall
GRT suggests that you should have gotten about 2932 fps with your factory barrel, so I would guess that it had a slightly looser bore. It also suggests that you should be able to go up to 64 gr before exceeding SAMMI spec on pressure, so I would guess that the 64.5 gr would be accurate as far as indicating pressure signs (which would tell me that the pressure model is at least close, especially noting the slower speed on the previous load). It says that you should be fine with your 62.5 gr start, putting your expected velocity at 2990 fps. If you're substantially over 3K, I would say that you will want to back it off. It looks like 3050 will be about your max with that combo, which again happens at 64 gr.
Thanks for your input here. After some more consideration of Alliant published data, my own experience, and your post, I loaded the first 10 barrel break-in rounds at 60.5 gr.
 

Muddyboots

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I use RL16 a lot for 180's in 300WSM but I started to use HV100 with really good ES SD and accurate. Hodgdon actually has load with the 180 Scirocco and HV100. Might be good backup.

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