I've always used rl22 for my 300 wby with a 180gr partition. However, after I got a chronograph I've seen some bad velocity variations with my loads. One range session yielded velocities from 2950 to 3140. This rifle has always been somewhat inconsistent, and now I see why. I've seen on here that others have had similar results using rl22 in the 300 wby. Some say it's temperature, some say it's due to the powder having a narrow sweet spot, and some say that one is the result of the other. I'll be honest, I only started using rl22 because it yielded the highest velocities in the reloading manuals. As I've matured as a shooter and re-loader I see the error of my previous thinking. From my research I see that some people swear by IMR 4831 and others swear by H4831. Is there really that much difference? I'm just looking for an accurate clean burning load somewhere between 3100 and 3200 fps. What do you guys think?
P. S. I can't believe I ever did any re-loading or muzzle loader shooting without a chronograph. I never go to the range without one now. If you're reading this, and you are trying to re-load without a chrono'. Do yourself a huge favor, and get a chronograph. Re-loading without one is like shooting with your eyes closed...
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I too have read that RL 22 can be inconsistent but what I've seen said is that others have seen variations between lots but haven't seen mentioned that the same lot number varies except some difference between hot summer and cold weather.
I've used 3 different lots of Norma MRP, the equivalent to RL 22, and have been satisfied. Consistent from lot to lot with my powder and rifle and only a little variation from cold to hot conditions.
My old, middle 80's Weatherby data sheet, used Hodgdon H4831 in all their recommended loads. Just for some added information from this data sheet:
This is with Weatherby brass, Fed 215 primers, and Hornady 180 grain bullets using H4831 powder. It will show that H4831 gives about 100 fps slower velocity than using Norma MRP powder.
80 grains H4831--180 gr Hornady--3060 fps---50240psi
82 grains H4831--180 gr Hornady--3145 fps---54310 psi
Norma MRP powder--81.8 grains--3245 fps-----51800 psi
This data sheet says not to load above 55,000 psi
Data in my Weatherby data sheet for 200 grain Nosler Partitions using H4831 versus Norma MRP powder:
77.2 grains Norma MRP---200 Nos Part---3000 fps---49000 psi
H4831---76 grains---------200 Nos Part.---2858 fps--46480 psi
H4831---78 grains---------200 Nos Part. --2926 fps---50620 psi
H4831---80 grains---------200 Nos Part. --3029 fps---54,690 psi
Note again Weatherby says no loads over 55000 psi and the top loads above may be too hot in your rifle.
This is just for added info for your Weatherby. I've shot some loads using IMR 4831 but didn't get the velocity that Norma MRP showed.
I have tried a few powders in the 300 Wby and stopped looking after I tried N165. My gun is a Rem 700 with a Pac-Nor barrel that is 28" without a brake. I am getting 3350 fps with 180 gr Scirocco II bullets, Rem brass, Fed 215M primer, and VV-N165 powder. It shoots right at 1/2 MOA also. In fact, I just loaded up 100 rounds that should get me through the next decade for hunting.
From my research I see that some people swear by IMR 4831 and others swear by H4831. Is there really that much difference?
I used to use IMR 4831 in my 30-06. I would get a POI difference of more than 2 feet at 300 yards from the winter/summer temperature swings. With H 4831 I get maybe 3 inches.
Nowadays, I don't even consider using temperature sensitive powders.
To add... The last load I developed using H 4831 had a ES of 5fps. That's in a 30-06 using 180gr bullets; I don't know how well that translates to a 300Wby.