IMR 7828 in a 7mm RUM

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CanXB

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Hello all

Looking to reload some 175gr Nosler partitions. Nosler shows that the most accurate load was 79.0gr of IMR 7828. Not having any IMR 7828 I went to my LGS. On the shelf was IMR 7828 SSC. Can these two be intechanged equally or will I need to reduce the SSC charge because of the smaller kernel and increased surface area? Never ran into this before so I thought I would put this to people that would know better than I. Thanks for any advice you guys can give.
 
The most accurate load in their test rifle, may not be accurate in your rifle. In any case, IMR 7828 is a decent choice in the 7mmRUM for lighter bullets, but it is too fast to obtain optimum velocities in the 7mmRUM with heavier bullets.
 
Thank you stubblejumper. The reason for starting there was due to it being the most accurate load from the Nosler manual for 175gr projectiles for 7mm RUM. Do you know if the SSC and the standard cut kernels can be interchanged directly?
 
They are supposed to be fully interchangeable.
Always good to start lower if changing over though, just like you would if changing lot numbers.
Dave.
 
stubblejumper said:
The most accurate load in their test rifle, may not be accurate in your rifle. In any case, IMR 7828 is a decent choice in the 7mmRUM for lighter bullets, but it is too fast to obtain optimum velocities in the 7mmRUM with heavier bullets.
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The Vihtavouri Burn Rate Chart shows the SSC to be slightly faster burning than the standard IMR 7828. It would mean you should a bit less powder. Hodgdon does not offer loads for the IMR powder for your 7 RUM. Regardless I find IMR powders to be too temperature sensitive, and prefer the Hodgdon Extreme powders. I also agree that the IMR 7828 is too fast for your 175 grain bullet. I would get Retumbo for your load, and if you can't get it, then H1000.

I ignore the claims of "most accurate load" in reloading manuals. It is meaningless. I look for the slowest temperature insensitive powder that achieves my velocity while filling or nearly filling the case. Accuracy is determined by getting the right velocity for your barrel, as well as the right seating depth for your bullet.
 
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I shoot a 7 RUM, but can't be any help as mine loves 160 ABs and although I bought some to try I haven't shot any 175 Parts yet.
Retumbo has given the best velocity and accuracy in both my 7mm and 300 RUMS, you might want to try a pound in yours, especially with 175 gn bullets.

 
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