H4831SC VS IMR Enduron 4955

[Loudenboomer]

Had some interesting results from some Informal testing yesterday during barrel break in.
.284 Win Rem action 30.5" Bartlein Barrel. Fire forming factory new Peterson Brass. 180 JLK VLD 2 thou. neck tension.
H4831 SC 55.2 gr Fed 210 primer 2 groups Ave. vel. 2824 High Extreme Spread 18 Low ES 12
IMR 4955 53.4 gr CCI 200 primer 2 groups Ave. vel. 2798 High Extreme Spread 18 Low ES 12
I was gunning for Vel . spread but I did shoot the 4955 a little better.
These are indeed similar performing powders.

 

[Kasimir58]

I compared 42.4 gr of H4831 and 42.4 gr of IMR 4955 with 130 gr Hndy ELD 6.5 CM. Used LRP brass (S&B), 210M primer, bullets seated into lands. Shot from 28" Shilen barrel.

Enduron powders are double base (yet extruded) so I also shot 42.4 gr of IMR 4955 with WLRM primer.

Eight shots each condition. Vel H, Vel L, Vel A, ES, SD

4831 210 M 2720 2685 2700 35 15
4955 210 M 2813 2731 2773 82 24
4955 WLRM 2848 2709 2812 139 42 one shot (2709) was much lower than the other seven for which SD was 17 - don't know why that happened, all loads were weighed with care

In my application 4955 is hotter than 4831. Use of magnum primer produced even more velocity which leads me to believe that using magnum primer is the right thing to do. I have mailed IMR about this. Disappointingly I heave not received a response in weeks.

I have always struggled to consistently produce small ES/SD despite paying a lot of attention to details of brass prep and weighing loads on balance beam scale. So I won't speculate about what powder is more consistent for velocity. But it is clear that the lowest velocity of 4955 (2731) was higher than the highest velocity of 4831 (2720) using the same 210M primer. And velocity goes up another 1.5% or so with a magnum primer.

 

[asquared19]

any word back from IMR? I have 8lb and am starting loads for it in my 300wsm, and if i can use the same powder for the 6.5CM it would be great.

 

[SeabeeKen]

CM might do better with 4451

 

[Hankpac]

I’ve played with the 4955 a bit…tbh i stopped because it goes from no pressure signs AT ALL to a sticky bolt and cratered primer within 1 grain charge difference in my .300 Winnie a few years ago. Kind of freaked me out, never seen quite that degree of “okay…okay…okay…NOT OKAY!” with any other powder I’ve worked with before.