Question for Dave King 338 RUM

MOA

Well-Known Member
Joined
Nov 10, 2001
Messages
92
Location
California
Dave, I too have a 338 RUM sendero. I read a post you made reguarking the 300 SMK. You state that RL 25 is better. I'd expect this with the weight of the bullet. How much better is it (velociy). I've only used RL 22 (actually I just finished breaking it it) because I've been unable to find data with RL 25. I got a lot of data from accurate reloading (at your suggestion) but am still seeking more. Please post data, anyone else?
 
G

Guest

Guest
MOA - I worked up a load for the 300 MK using Reloader 25 in my 338 RUM Sendero. I started at 85 grains/RL25 and worked up to 91 gns. I intially settled on 90.0 grains of RL25 but found faint pressure signs on the cases after a hot day shooting. I dropped back a grain to 89.0 gns for 2605 fps. It easily shoots sub-moa in my Sendero.
I have since switched to using H1000 instead of Reloader 25. When the weather cooled, the velocities fell off to the 2500 fps range using the same 300 MK/RL25/89.0 gn load.

300 Sierra MK
88 degrees F - 89.0/RL25 avg - 2642 fps
70 degrees F - 89.0/RL25 avg - 2605 fps
30 degrees F - 89.0/RL25 avg - 2498 fps
This translates to a 2.5 fps loss per degree F for Reloader 25. I found that Reloader 22 also behaves the same way in my 300 Win and my 340 Wby.
This troubled me for it could play heck with my drop charts, so I looked at other powders to see if they behave the same way. I have tried H1000 and found it is only showing a 35 fps drop between 70F and 30F - so far. My load using H1000 is the same as Reloader 25 - 89.0 [email protected] fps. I have a small amount of IMR-7828 that I have considered trying also, as I have read the IMR series of powders show minimal velocity/temperature spreads.
I have used H870 for the same velocity and accuracy but I have to use 8 gns more powder to match RL25/H1000's velocity. Hope this helps you a little.
 

Dave King

Well-Known Member
Joined
May 3, 2001
Messages
2,366
MOA

I only worked one day with RL22 and E-Mailed the data away. I'll see if I can dig the original data up from some hardcopy data.
 
G

Guest

Guest
moa - I think RL22 is a little too fast to use with the 300 MKHP to acheive top velocities. I have used RL22 with the 210 Nosler and the 250 Sierra BT. It showed good velocities and accuracy.
 

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