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300 RUM, 200 AccuBond + Retumbo Results:

 
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Old 08-19-2003, 10:00 PM
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Location: Mukilteo, WA
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300 RUM, 200 AccuBond + Retumbo Results:

I finally got a chance to do some loading and shooting and have found my new “do everything load” for my 300 RUM. I know some out there are looking for results/experience with these components, so here you go:

The Rifle:



My rifle isn’t some big heavy bench gun or expensive custom gun. It’s just your average run-of-the-mill A-Bolt Composite Stalker. [img]images/icons/wink.gif[/img] It has the factory original (pencil thin) 26” barrel with well over 1,000 rounds through it. About ¾ of those were from when it was a 300 Win Mag before I had it rechambered to RUM. The only accuracy mods I’ve done to it are a Moyer’s trigger, and relieving some more material from the barrel channel of the much-too-flexible composite stock to make sure the free-floated barrel stays free-floated (it must have been something to do with the increase in recoil of the RUM, but right after I got it rechambered it wouldn’t shoot worth a damn—-the barrel contacting the stock was the problem). The scope is a Leopold 3.5-10X50mm with Stoney Point Target Knobs.

The Load:

200 Accubond , 95 grains of Retumbo, brand new completely un-prepped Remington cases, Federal 215 primers loaded to 3.60” OAL, 3177 fps.

I started out with H870 because I had a bunch I wanted to shoot up and I thought I could get some good velocities. I was easily able to beat the above velocity with it. I didn’t get a pressure sign (in my rifle the first sign is an ejector mark) until a round clocked 3311. Backing off quite a bit still put me at 3246, but the load just wouldn’t shoot. I think it’s because I was in too big a hurry to pack all that powder in the case properly so I was compressing it so much the seating depth varied widely. Anyway, it wouldn’t shoot and H870 is dead. Enough about that.

96 grains of Retumbo yielded 3208 and no pressure signs. I didn’t clock 97 grains but I’d expect it would have gone around 3240. I got a slight ejector mark with that one. Extraction was unchanged—still a finger-tip affair.

So I backed off to 95 grains. What this powder lacked in velocity, it made up for with consistency. Three randomly picked rounds went 3171, 3183 and 3179. I know it’s only three rounds but I’ve never had an extreme spread of 12 and a standard deviation of 5 before even with only three rounds. This is with “as thrown” powder charges, no less. I knew right there this load would be more accurate.

Disclaimer: I feel this load is safe in my rifle but if you try it in yours you will die, guaranteed. Don’t try it. You will die!!!

OK, now that that’s out of the way, I can tell you that my rifle has a rather sloppy chamber and with rounds seated to 3.60” to fit in the magazine it basically has a free-bore as well. So you really might run into pressure signs before I did. This is backed up by Brent Moffit’s data—at 90 grains he was at 3082 fps while I was only at 2977 fps. At 92 grains I was still only at 3062 fps. So really, work your way up to this slowly guys—especially given the tales of Retumbo acting completely differently for different people. Be safe.

The Bullet:

I now realize I forgot to take a pic of the bullets before firing. Oops. Sorry. You all know what they look like anyway.

I have been waiting for a very long time for somebody to make a heavy, high BC 30 bullet with reliable terminal performance. I was actually close to setting myself up to swage my own bullets so I could make what I want. Well, Nosler came through. It seems so far they did it well enough I might not have to get into the swaging business. Don’t get me wrong, there is nothing “earth-shattering” about the terminal performance of these bullets. Some bullets will do some things better. Other bullets will do other things better. But this bullet lived up to my expectations (as far as I could test it). It seems like a very good all around bullet for my purposes.

I apologize for my lack of photography skills and/or equipment. Damn I need a digital camera! Anyway, these pics were the best I could do. I hope they’re good enough for you guys:







The bullets from left to right are the 180 Scirocco, 180 XLC, and 200 AccuBond. The bullet of each type on the left is a simulation of a long range impact with minimal resistance. Each on the right is a simulation of a normal range (like 250 yard) impact.

The “long range” Scrirocco retained 88.7%, the “normal range” retained 78.2%. Great weight retention but they didn’t penetrate very far—as one would expect with them opened to such a huge diameter.

Both XLC’s retained 99%, of course. The “normal range” XLC is what I’m used to seeing from my tests and the reason I used X bullets exclusively for so long. Absolutely perfect! It’s the “long range” one that’s disturbing. It hardly opened up. The wound channel was tiny. As you can see the shank is slightly bent. This is the only bullet that didn’t penetrate straight. About ¾ of the way in it took a 45 degree turn to the left. I could attempt to explain why with some Euler column buckling equations but I won’t. [img]images/icons/shocked.gif[/img] I’ll just show you what happened.

The AccuBonds retained 76% and 64%.

They don’t look all that impressive. Much the same as a Partition doesn’t look all that impressive compared with some of the “pretty” mushrooms some of the custom bonded bullets give. But Partitions always get the job done. If this bullet mimics their performance, I’ll be more than happy.

In an impact where the XLC hardly opens up and doesn’t penetrate straight, these open up just fine and go straight. In an impact where the Scirocco is nearly turned inside-out, these hold together and penetrate farther. A pretty good compromise between the two.
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Old 08-19-2003, 10:01 PM
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Re: 300 RUM, 200 AccuBond + Retumbo Results:

Here’s a bunch of them recovered from 2900 to 3300+ fps:







As you can see, they don’t look that much different. As the velocity increased, they simply got a little bit shorter and shed a bit more of their weight. Their frontal diameters remained virtually constant. At the front of the mushroom they were all right around .48”. On some of the lower velocity impacts the overall diameter was a bit more because the nose jacket hadn’t broken off or folded tightly against the shank yet. This didn’t seem to affect penetration much though. I think the area right at the front of the bullet is probably the determining factor there. But the higher velocity bullets did penetrate slightly more—the opposite of how the X and Sciroccos did. Although I would guess an impact that simulated a hard hit at close range might have increased the penetration of the XLC over the “normal range” test had some of the petals come off. I would also guess such an impact with the Scirocco would make it look like you’ve seen in other tests here—totally inside-out, without very good penetration. But that’s just my conjecture....

Like I said before, each bullet does different things better. For the all around performer, I think the Accubond will suit me well.

It will open up easily at extreme ranges with minimal resistance. The Scirocco is probably even better in this respect. A shot on a deer at long range clean through the lungs? I’d guess a Scirocco will do more damage and kill more quickly. That’s a good bullet for this application. I’m not so sure the XLC is. Both the other bullets are making huge wound channels before the XLC is even opened up. I don’t feel it would be a good choice for this situation.

Elk in the ass at 20 yards? That’s what X bullets are made for. They are they obvious choice (in my test at least, I’d expect the Failsafe to be similar). Extreme penetration. The AccuBond isn’t going to do quite as well in this situation but it will beat the pants off the Scirocco—or any other “standard” bullet for that matter I’m convinced. While it won’t be an X bullet, it should get the job done. It isn’t going to flatten out like a pancake, it isn’t going to come apart, it’s simply going to expand to about 1.5 times its diameter, hold about 2/3 of its weight and keep going—much like the Nosler Partitions I used for so long.

So, it looks--at least to me from my testing--like this bullet will be a good terminal performer in about any situation in which I could put it. Maybe not the best for that particular situation, but it should get the job done.

Here's a pic of them all lined up:



Of course none of this means a damn thing if you don’t hit where you’re aiming.
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Old 08-19-2003, 10:05 PM
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Join Date: Dec 2001
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Re: 300 RUM, 200 AccuBond + Retumbo Results:

Accuracy:

Well, how’s this?



That group measures 2 ¾”. It was shot in variable 5-15 MPH (my estimate) crosswinds—at 400 yards. I had 7 clicks to the left dialed in. I was leaning over the hood of my Trailblazer on a couple sandbags—not exactly the "ideal" bench rest set-up. But it was good enough to tell me how accurate this load is. That’s actually the first and only group I shot from 400 with that load that wasn’t from field positions. I like to “quit while I’m ahead.” [img]images/icons/grin.gif[/img]

This group really made my day. I had spent most of the day getting the crap beaten out of me by the rifle while shooting shotgun patterns with the H870 load. This group told me that I had found my load, it validated the rifle’s accuracy and my shooting ability and it was a good note to end on for the day. I had one big bloody (literally) smile on my face after shooting it. Just imagine if there had been no wind and I had been shooting off a real bench? [img]images/icons/grin.gif[/img]


Here’s a 5 ¼” group shot in close to the same conditions as above. From 700 yards. I had 12 clicks of windage dialed in.



Yup, it’s a bit low. I was going off the computer printout for the faster H870 load.

I know that may not impress many here to much, but that's OK, I'm happy. [img]images/icons/smile.gif[/img] That's why I posted the specs on the rifle and my shooting set-up--pretty much a cheap factory, light weight, hard kicking rifle being shot in much less than ideal conditions. I think I did pretty well considering....
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Old 08-19-2003, 10:36 PM
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Join Date: May 2001
Location: Pennsylvania
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Re: 300 RUM, 200 AccuBond + Retumbo Results:

Excellent report on bullets, and loads.

Did I miss the 200, 220 and 240gr Match King bullet pics?????

Later
DC [img]images/icons/smile.gif[/img]
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Darryl Cassel
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Old 08-20-2003, 10:28 AM
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Join Date: Jul 2001
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Re: 300 RUM, 200 AccuBond + Retumbo Results:

Great report and pictures. Always great when someone takes the time to share info and experiences.

I too will be doing some testing with the Accubonds when the forest fires stop raging. I will be launching them from my new RUM. I will also use Retumbo and expect to be in that 3200fps range (35" barrel). No fears about the accuracy or ongame performance. Just something new to try.

Like you, I am also suffering from inconsistent performance and H870. I believe the high ambient temps are causing most of my grief. Starts off shooting well then sprays as barrel temp goes up. Big heavy barrel so don't think that is warping.

Thanks Ian for the samples...

Jerry
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Old 08-20-2003, 04:12 PM
 
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Re: 300 RUM, 200 AccuBond + Retumbo Results:

Jerry--
You can expect 3400 from your 35" barrel with the Retumbo and the 200 gr Accubond. I'm getting 3200 from a 25.5" K&P on a standard .300 RUM with 94.5 gr of Retumbo and the 200 gr AB.
Jon--I really appreciate the info--I was wondering what the AB would in terminal performance and I am impressed. I sometimes shoot deer as close as 30-50 yards and as far out as 800 in some of our bean fields and I haven't had a SMK failure yet but the AB is just a little more insurance against shedding the jacket on the close shots and the BC is .588--good enough for shots out to 1000 with the RUM...
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Old 08-20-2003, 04:31 PM
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Posts: 1,459
Re: 300 RUM, 200 AccuBond + Retumbo Results:

Chris,
will find out about the vel in the future. Only getting 3000fps with H870 and 240gr MK, so 3400fps may be optimistic. Would be nice...

I am surprised at the bc of only .588. The bullet is as long as the 220gr MK which is rated over 0.6. My guess is that companies are taking a very conservative approach to their bullet performance.

If the Hornady SST/Amax are an example, these poly tip bullets fly flatter then their book BC would suggest. Would be interested to see how much elevation you need to go 1000yds from a 100yd zero. This would give us a ballpark on the real world BC.

Jerry
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