Hi,
Looking for new loads for my .300 Weatherby with 172gr Speer Impact other than the one supply by Speer, because the only powder I have from their data is with IMR-4831 and I have a lot of IMR-7828SSC and RL-22 and no data that are very good for the .300. Anyone has loads with these powders and the Impact Bullets.

its a 172gn projectile...... find data for a 175grn..start 10% below and work your way up...like you will have to do anyway no matter what data you find,even if its projectile specific.......all the older manuals tell you to do this.
not familiar with that particular projectile but MOST speer projectiles are lovely and soft..which equals easy to push out of barrel so not super high pressure.
find RL22 OR IMR-7828sc load close to it and work up.

I have no specific data for the 300WBY, but I'll say my 7STW loves 7828SC. Better than any other powder. I push 160 gr Accubonds at 3200fps very accurately.

-DallanC

Elvis wrote:

its a 172gn projectile...... find data for a 175grn..start 10% below and work your way up...like you will have to do anyway no matter what data you find,even if its projectile specific.......all the older manuals tell you to do this. not familiar with that particular projectile but MOST speer projectiles are lovely and soft..which equals easy to push out of barrel so not super high pressure. find RL22 OR IMR-7828sc load close to it and work up.

Not this time,
Anyway I will work up some loads with the powder I have but here is some data from Speer manual #14 I have compare to what they give for their new bullets:
180gr. Grand Slam or Hot core with Reloder 19, max= 78.0gr.
165gr. Grand Slam or Hot core with Reloder 19, max= 80.0gr.
and for the 172gr. Impact with Reloder 19, max= 85.5gr. As you can see there is something different in the construction of their new bullet if you can go that high for the max load with that powder

so again...IF you have started low and work your way up...you will keep going till strike pressure then back off LOL.... you wont go wrong as such..just will take a few more loads till you get there...IF INDEED you are chasing top velocity...