180 and 200 gr Accubond in the .300wm

Stats Shooter

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CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

I recently puchased a Model 70 Supergrade .300wm. It is my 3rd .300wm rifle including an F-Class rifle and a Savage 110F that I have had since about 1994.

I decided to build a load around the .200 grain Accubond. I will be using this rifle for annual elk hunts in Eastern Utah and Western Colorado.

In my Savage, the load I used was 180 grain accubonds, H-1000 powder, CCI-250 primers, and Remington brass. I found the best accuracy in that gun, with that combination to be around 2900fps with a COAL about 3/100 longer than SAAMI. This load shot a consistent 1/3 MOA in a factory savage.

With the new model 70, during breakin, I had some 180 grain Accubonds still laying around so I loaded them up in Norma brass, seated them to 1/100 shorter than mag length (which is 3.400), and using quickload, I ballparked 2900 fps and began my breakin ritual. This load was 2880 fps and shot about 2/3 MOA. Im sure I could have improved the accuracy tweaking the load, but was pleased that both rifles like the load.

So over the last week or so I did my workup for the 200 grain accubond. I called Nosler and they informed me that the tip-ogive of the 200 and 180 grain accubonds, and the bearing surfaces were identical. The additional weight is mainly in boattail length and construction. So I expected that the best accuracy with the 200 grain accubond would also be around 2900fps.

The components used in this load are Norma brass, CCI-250, H-1000, and 200 Grain Nosler Accubonds. CBTO of 2.2375 or approximately a COAL of 3.365.

Im not going to give the amount of H-1000 I used because this Model 70 is a slower gun with a generous chamber and thus requires almost 2 more grains of powder than my Savage rifle to achieve the same velocities, but I will say that Quickload says it is 79.5.

The test was performed at about 85 degrees and humidity so high that it would be beneficial to have gills to breath with. Fortunatly H-1000's temperature sensitivity factory is about 0.21 fps/degree or it takes about 5 degrees to increase/decrease your velocity by 1 fps, and I find this to be true as my F-Class rifle will have a very hot barrel by the end of the string and my vertical POI is still in the 1/2 MOA x-ring.

The 2 best 5 shot groups were 0.421 at 100 yards and 0.766 at 200 yards with an average muzzle velocity of 2911 fps and extreme spread of 12 fps. (2906-2918fps) with a Quickload equivalent of 79.5 gr H-1000.

There was another accuracy node around 2700fps but it wasn't as tight (1/2-3/4 MOA) and for a hunting load, I generally prefer more energy to less..especially since this isn't a target load or won't be used for target shooting at all.

What I find interesting is that the sweet spot for two different bullets with very similar construction, in two different rifles, were almost the same. This adds some validity to the chris long theory of optimal barrel time. Also, though it is a small sample, it implies that when magazine length limitations are a factor, tangent ogive bullet's with seating depth insensitivity are a good choice.

In short, if you are looking to load the 180 or 200 grain spitzer, non -LR, accubonds, you may want to work around 2900 fps and H-1000 is an excellent powder for this cartridge/bullet, and for the .300 wm in general.
 
Since it's over book, let's put the required warning in. Probably not over pressure, though, in a real world loose production chamber.

Since the same loads hit a sweet spot in two different guns, a question that seems obvious to ask is if the throats are close to giving the bullet the same amount of jump in these two chambers?
 
No the throats were not equal. I checked my notes and the Savage had a throat (at least back when I measured it ) 0.013" longer when I developed that load. I'm not sure what it was when it was factory new, but back then I shot factory ammo and I probably put 400-500 rounds through it before I began hand loading for it.

I don't know if 0.013" is "close", but obviously not exactly the same....I would at least say that nosler AB's are not terribly jump sensitive. Which is a great attribute in a hunting bullet with magazine length restrictions.
 
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