7mm Rem Accumark Load Testing

[liltank]

You may want to try some traditional powders like H4350, IMR 4350, H4831, IMR 4831, and H1000, RL19, RL22, and RL25. They are little faster and may provide a little better velocity with out the compaction you are experiencing with the Retumbo. Just a suggestion.

Tank

 

[Autorotate19]

Sorry your right. My coal is 3.368. Thanks for all the help, Im heading to the range right now so Ill let you know how it goes.

 

[Autorotate19]

Went back today. Here is my reslults at 200 yards no wind.

70.7grs- .38" and .55"
73.5grs- 1.68"
74.0grs- 1.25"
74.5grs- 1.29"
75grs- 2.5"

I didnt find any pressure signs but with 75 grains there was a lot of powder crunching so I didnt go any higher. This confirms that my gun really likes the 70.5-71 grain range or so it seems. Berger said that at their 70.4 gr max they were getting 3022 fps.

 

[Pdvdh]

I don't get those MVs at 70 grains of Retumbo, and that seems optimistic. Hodgdon's online data shows 2899 fps for a 170 grain Sierra bullet with 75 gr Retumbo.

170 GR. SIE RN Hodgdon Retumbo .284" 3.270" 71.0 2752 44,200 CUP 75.0C 2899 50,700 CUP

The reason I say Retumbo is going to be about the best powder going for the 7mm Rem Mag with the 168 VLD is because that's the powder of choice for the 'Best of the West' and they also use the 168 Berger VLD. They spent a lot of time with that combination and have stuck with it.

I spaced it that your groups were at 200 yds. I was thinking 100 yds. Your original Ladder test data set is much more reasonable at 200 yds, and I don't doubt their validity one bit. Especially now that you've gone back out and duplicated the good performance at the same two powder charges as the first group.

You've just successfully implemented the Ladder method of load development. Wasn't as hard as you thought, eh? You'll continue to increase confidence in those powder charges with additional shooting.

You've got a good load at ~70 grains and another good load in the 74-74.5 grain charge, which is about where I load (74.6 grains).

Thanks for the follow-up post. It doesn't always come around so quickly, and it doesn't always work as slick as your first experience. You must be a pretty good shooter to duplicate the data so closely - it wouldn't appear you're shooting is problematic. This method of load development is a reasonably efficient way to hone in on better, rather than worse, loads for a rifle.

I'd be pretty happy with the accuracy even at the 74-74.5 grain load. If you're gonna shoot at game at 800-900 yds, now you just need to confirm similar retained accuracy (moa-wise) at those extended ranges.

Cheers!

 

[Autorotate19]

When I get a chance Im going to chrony it to double check. Thanks for all the help and suggestions. Down the road ill tweak with the charge etc but for now Im satisfied. I agree that the other loads shoot pretty good too. Its still well under 1 moa. Thanks!

 

[Autorotate19]

Liltank, Thanks for the suggestion. I only have Retumbo and H1000 at the moment and now that I found my gun likes it pretty good I think ill stick with it. If I try a different powder it would be like starting all over again. Like I said earlier I dont like to mess around much. Once I find a load my gun likes I stick with it. But thanks for the idea if anything down the road ill try some h1000 and see how it goes. Thanks

 

[Topshot]

Good to see you got much better results on Day 2. with no wind.
Day 1
69.5grs - 3.9"
70.grs- 2.7"
70.5grs- .9"
71.0grs- 1.3"
71.5grs- 5"
72.0grs- 5.4"
72.5grs- 2.4"
73.0grs- 3.1"
73.5"grs- 1.8"
Day 2
70.7grs- .38" and .55"
73.5grs- 1.68"
74.0grs- 1.25"
74.5grs- 1.29"
75grs- 2.5"

Pitty that you didn't shoot the 71.5 and 72gn loads again. I would not be surprised if these loads also shot much better. Sample size is important in order to get a true feeling for what load your rifle likes.
Having said that, it looks like from your results that you have at least one accurate load that you can use. So that rifle can shoot quite well.
A change to a faster powder might give you higher velocities and good accuracy.
Good luck.