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- Thread starter Muddyboots
- Start date

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Dean

Dean

I don't see how this could be useful.

From best TESTED CBTO, you can just adjust powder charge upward to dial in anything achieved with your wondering.

Looks like you got the answer, but to your original question. I just did a seating depth test this weekend from .030” off to .100” off in .010” increments. Chrono’d all shots. SD of 9, ES of 37 with 24 shots. The average for each seating depth was within 10fps fastest to slowest.

Perfect! What was the bullet, powder combo?

This isn't a large enough group to be statistically relevant, but it was so odd I knew where to find it in my notes.

300 RUM, Nosler ABLR 210gr, WLRM primer, 81.0gr IMR 7828SSC.

COL / FPS (avg 5 shots):

3.543 / 2800 (.125" off lands)

3.596 / 2805 (.072" off lands)

3.628 / 2814 (.050" off lands)

3.658 / 2823 (.010" off lands)

The hidden detail here is that each of the ES ranges overlapped with at least the seating depth above/below it. The averages just make it look like it's moving up with the bullet out further. The whole string was ES 39, SD 13, which is not too good.

300 RUM, Nosler ABLR 210gr, WLRM primer, 81.0gr IMR 7828SSC.

COL / FPS (avg 5 shots):

3.543 / 2800 (.125" off lands)

3.596 / 2805 (.072" off lands)

3.628 / 2814 (.050" off lands)

3.658 / 2823 (.010" off lands)

The hidden detail here is that each of the ES ranges overlapped with at least the seating depth above/below it. The averages just make it look like it's moving up with the bullet out further. The whole string was ES 39, SD 13, which is not too good.

Last edited:

80eldm, 40ish grn H4350. Looked back at my notes, the larger jump was slower. Didn’t notice before, but the ES of the shorter coal had significantly better ES. The ES of the last 12 shots was 13.Perfect! What was the bullet, powder combo?

I didn’t fire enough shots to have any kind of statistical relavance, maybe with 20 shots at each length there would be something provable, but my results from 3 shots at each length was a drop in speed coming in closer to the lands. Thats said the es of each load cover basically covers the spread between loads. The longest bto is 0.010” off touching the lands.