Heavy hunting bullet for 10 twist, 26", 300RUM?

[Jon A]

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Sure would like to here from anyone out there that's put 240MK's (or similar) down a 26", 10 twist pipe in a 300RUM!

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I used them as much as any other in my factory 10 twist. Figure somewhere around 99-101 grains of US869 for around 2950 out of a 26" for a mild "summer safe" load.

With a measured BC only in the .640 range, you aren't going to gain as much ballistically as you will with the sleeker 210's, but I still really like this load and bullet better than the 200 AB for two main reasons:

1) It's easily more accurate in my rifle (with two different barrels).

2) Better terminal performance. I have yet to find any bullet that'll penetrate as deeply while making as big a hole as the 240 SMK. It is simply devistating.

[jmden]

Thanks for the input, Jon A.

Hey, what is your feeling of the Nosler 300RUM brass now that you've had it awhile? Can it handle higher pressure??

I remember your tests last year with several bullet and 2 chronos--great work. What's your feeling on why the measured 240SMK BC is SO much lower than Sierra published BC. Just looking at that missile, it looks like it should have a higher BC than .640, but it's hard to ignore the data you gathered...

Thanks!

[Jon A]

The 240 just doesn't have a shape as efficient as the more modern VLD's. The pudgy 6 caliber (if that) tangent ogive makes the various 210's, the ULD's I've shot from Richard, etc, with their sharp secant ogives look to have relative needlepoints in comparison. There really isn't a reason it should be higher; the only reason it's that high is because of it's weight. Sierra's data on this bullet is very old, I'd be surprized if they came up with the same numbers if they tested it today as I know they've changed some of their proceedures.

In any case, if it really had a BC that high it would beat the various 210's pretty soundly. The simple fact is, it doesn't.

But like I said, I still like it. That pudgy nose helps it work in 1:10 twists, makes it very easy to find an accurate load with (not picky about seating depth) and that extra weight is put to good use terminally.

On the Nosler brass, I haven't worn any out yet but I haven't loaded any one case more than three times or so I think so far so I can't give you anything definitive. It will show ejector marks as you get up there roughly as quickly as Rem brass. Even if the pockets do stay tighter a bit longer it doesn't seem to me like it's going to handle significantly higher pressures well enough to be much of an advantage. The main thing I like about it is it all weighs the same, the neck thickness is so much more consistent, etc.

[jmden]

Thanks again, Jon A. I really appreciate your learning from your experiences.

[jmden]

Some info via email from Kirby:

My original email:

I’d been hoping to hear from you on LRH regarding this, but am too curious to wait.

You had been testing some 215-220g .308 WC’s—I think they were the new Al tipped version. You mentioned on LRH that you were going to test them in a 10 twist. Did you get a chance to do that? I’m still wondering if there’s any chance that they might stabilize in my 10 twist, 26” at 300 RUM velocities.

APS first reply:

I did test them some in a Lawton 1-8 twist barrel but this barrel ripped them apart because of to much baring surface compression. I have a specially designed thin land Satern barrel that should be here anytime which should work much better with them but until it gets here I really have nothing more to offer as far as data on these bullets.

I can say there is really no chance I see of them stabilizing in a 1-10 barrel. A 1-9 possibly if driven to very high velocities but I suspect a 1-8 will be about perfect. Again, these are only predictions but I have shot them out of factory Rem 700 300 RUM rifles with 1-10 twists and they never made it to the target.

My reply:

OK. Thanks for the info.

I talked to Richard last night and he thought the new Al tipped 210’s should stabilize in the 10 twist, but with the thin jacket I’m not sure about close up shots with it and besides a morning and night spotting/longrange spot, most of my elk shots are going to be within a 100 yds or so in the trees. So, I’m a little leery of using them—maybe if Richard uses the thicker Hairfield (sp) jackets and is satisfied with their quality, I’ll look at them again. For now, I’ve got some 240 SMK’s coming.

What I really need is an APS 300AX with 30” barrel, 8-9 twist and some 265 WCs or wait to see what happens with these Al tips!! Now if I could just convince my wife that I NEED it!

APS second reply:

They may stabilize the 210s in a 1-10 barrel. Just have to get some in the air and see.

I have tested the 240 gr SMK in my 300 AX and they will survive the Lawton barrel just fine. Got them up to 3220 fps with WC872 powder which is WAY to slow in burn rate, ran out of powder volume long before I topped out in pressure.

I will be testing with US869 here soon with that bullet and suspect 3300 fps may be realistic with top end pressures.

I have kind of been holding off on 300 AX testing because I want to get RIchards bullets working with this new barrel. Ballistically, they will make all other 30 cal bullets simply obsolete.

I would agree with you on the jacket thickness on close range impacts with the large Aluminum tips. Richard upgraded his 338 bullets for me to a MUCH heavier jacket to handle the strains of 3500 fps launch speeds in my 338 AM but this will also make them a much better big game bullet as well.

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Can't wait to see what these new bullet will do when Richard and Kirby get 'em all figured out.

Hope this update helps someone.