300 Win Mag with 208 AMAX - Help

[SubMOAR]

Hello,

I have only been shooting for precision for about a year now and have been reloading for about 9 months. I reload for my 308 and 223 with great success. I have gotten my 308 and AR-15 to group sub-MOA consistently.

I have been trying to develop a load for a 300 Win Mag that someone I know owns, and have been having a really hard time finding a load that is MOA or better.

I anneal and outside neck turn, weight sort brass and bullets for load development.

Here are the loads I have tried.

Rifle: Savage 116 Bear Hunter w/ Accustock (Max Mag length is 3.500" - anything over will have to be single fed)
Optic: Vortex Viper HST 6-24
Chronograph: Magnetospeed

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178 AMAX @ 3.490" without a Comp/2.865" with a Comp (0.020" from lands)
Powder: IMR 4831 - 76.3 grains
Primer: CCI 250
Brass: Hornady Match and Federal Military
Velocity: 3,125 FPS
Result - 1.5 MOA'ish

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208 AMAX @ 3.420" (Factory Recommended) and 0.020" off lands.
Powder: IMR 4831 - 69.4 grains
Primer and Brass - Same as above
Velocity: 2,760 FPS @ Factory 3.420", a little faster at 0.020".
Result - 1.5 MOA'ish

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Currently switched to H1000 powder and trying to develop a load with that powder for the 208 AMAX. The owner is pretty set on the 208 AMAX as it can be used for hunting and banging steel at long range, and wants one load to do both.

I have done lots of research for H1000 powder and the 208 AMAX and people have had some seriously awesome results. I've seen pictures of 1/2 MOA or better at 100 yards with the combination.

I am just looking for some help with determining what COL most people find is most accurate. I have seen that most people had great success with 76.8 grains, but also some at 77.0, 78.5, and 80.0. Current Hodgdon recommends 78.0 = Compressed.

I tried 76.8 grains @ 0.015" from lands with groups coming in at 1.5 MOA. Although 4/8 shots went into the same hole, still have 4 fliers that I cannot account for though. I think that the H1000 will be the powder with best results seeing that my first outing with it today was pretty good. I may retest the 76.8 grains but seat the bullet at 3.500" (Mag Length) and see what happens. If that doesn't yield MOA or better, then I will start my whole process for 74-78 at 0.5 grain increments and the whole 9 yards. Not looking for short cuts, but what have you guys tried with the 208 AMAX?

 

[Trnelson]

Not specific to your setup or rig, but just my findings working with the 208 AMAX for one of my rifles. Measure cartridge base to ogive of all the rounds you load to test. I noticed that I had "unexplained" flyers in groups and re-tested I eventually figured out that after seating and measuring each load for testing, one was .0055" shorter than the other four seated with the same seating die at the same time as the others with no changes or adjustments and I marked the case and when I shot the group at 200 wouldn't you know that bullet went 1-3/8" low outside of the neat 1-1/2" group of four. After repeating this test twice more and validating the result I went away from the 208 AMAX. YMMV.

 

[lee31]

I would load up 5 rounds at different lengths from 5 thousands to 30 thousands jump then maybe 5 at 5thousandths jam . I would also keep with the h-1000 . Maybe even Retumbo

 

[FEENIX]

See 21 and 23 of http://www.longrangehunting.com/forums/f28/300-wm-seating-depth-208-gr-max-159745/index3.html

 

[SubMOAR]

So I decided to load the 208 AMAX to max mag length which is 3.485", since this rifle and load will be used for hunting. A shorter COL reduces the max powder capacity so I filled cases to see which one got me closest to compressed with my FC military brass, and came up with 75.0 grains of H1000 is max with my 3.485" COL.

Did a test with the magnetospeed. 72.5, 73.0, 73.5, 74.0, 74.5, 75.0 of H1000.

My accuracy node became very apparent from 74.0 - 75.0, possibly even past 75.0 but I would be compressing powder at that point. I checked the velocities and 74.5 grains was 2,707 Avg. and 75.0 was 2,721 AVG. Both had a SD of 10, and Extreme spread was 22 for 75.0, and 28 for 74.5. With the velocities only having a difference of 14 FPS, I have more room for error with my powder charge, and lot inconsistencies.

So I am definitely liking the 74.5 and 75.0. My next test will include running 74.4, 74.6, 74.8, 75.0 and seeing where my accuracy and velocity plateau and I am fairly certain that I will have my load developed (4 shots into 1" or better consistently is acceptable to me with stable velocities).

4 Shots - 74.0 had a center to center group of .850", 74.5 was .700", and 75.0 grains was .865".

I used the 208 AMAX bullet as a reference for size.

 

[SubMOAR]

Range results of my final load development.

My new load is going to be 74.6 grains of H1000 with the 208 AMAX, seated at 3.485" (Mag Length).

74.6 grains was 0.685" center to center with the 4 shots. Pretty sure I pulled the last shot also, I bet I could get all 4 into one ragged hole.

This development went very smooth, I will recommend H1000 powder from now on for the 300 Win Mag.

Although I messed up on 74.8, I am pretty sure that it is a lot more consistent that what I printed.

 

[Trnelson]

That's a pretty nice result indeed. H-1000 works great with the 300 win mag and those larger pills. I just couldn't get rid of that flyer which was more pronounced in my rig. I always check out Hornady bullets first as they are "local" and usually available at the local outlets.