240SMK with 300 RUM

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by trader388, May 26, 2004.

  1. trader388

    trader388 Well-Known Member

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    Anyone getting over 3000fps with this combo?
     
  2. Nighthawk

    Nighthawk Well-Known Member

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    Ask Brent or Boyd Heaton, I think one or both of them get like 3200 plus, but their barrel lengths are like 30" or more.
     

  3. Charles A

    Charles A Well-Known Member

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    You should beable to get about 2800-2900 in a factory 26in barrel.
     
  4. trader388

    trader388 Well-Known Member

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    Thinking about a 28" Rock Barrel.

    Also looking at the 210berger or JLK. Experience and opinions appreciated. [​IMG]

    [ 05-27-2004: Message edited by: trader388 ]
     
  5. Mysticplayer

    Mysticplayer Writers Guild

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    trader, been shooting a 300RUM and 240gr MK using both H870 and H50BMG. The H50BMG is the better powder and I get 3075fps from my 33 1/2" barrel.

    Shoots very well at LR and hits hard.

    Depending on the barrel, getting 3000fps might be pushing things a bit from a 28" barrel. You may get the speed but wonder if it will be accurate.

    Jerry
     
  6. Brent

    Brent Well-Known Member

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    220 SMK I can get about 2950 fps in the 26 in. tube, and I'm sure I'd get less with the 240gr, I just haven't tried it in my 300 Ultra yet.

    I think 3000 fps is pushing things hard in a 28 in. tube. A 338 cal. and you could get away with it, 30 cal... I'm "guessing" is topping 75,000 psi or better if you do.
     
  7. Digger49r

    Digger49r Active Member

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    I'm using 230gr Wildcat Bullets ( the new ones, made in Canada ) with a Fed 215M primer and 88 gr of Retumbo. Velocity is aprox. 2900. Accuracy is Sub MOA, better then the 220 gr SMK's.I think that's as heavy as I want to go though.
     
  8. Jon A

    Jon A Well-Known Member

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    Anybody use Retumbo for 240's in the 300 RUM?
     
  9. Guest

    Guest Guest

    I have gone as high as 86rs of Retumbo with the 240 SMK in my 29" 1-10" twist Lilja barreled 300 RUM, accuracy was best at 82grs. I haven't chronoed it yet and didn't get any real high pressure signs, bolt lift wasn't hard at all and the primers looked good but was starting to get ejector marks in the brass at 84grs. My other RUM does the same thing and I think it's the Rem brass. The primer pockets get loose real fast when I see those ejector marks and I'm not shaving any brass, just seing marks.
    Wayne
     
  10. Jon A

    Jon A Well-Known Member

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    Thanks Wayne.
     
  11. Jon A

    Jon A Well-Known Member

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    I figured I'd post some results. My rifle probably has a sloppier chamber than many (116.2 grains water capacity of fired cases) and it has a nice factory freebore but my short magazine limits loads to 3.60" OAL, so these powder charges may not be safe in many rifles even though they're pretty mild in mine. But it should give you guys an idea of the velocity potential of each powder as I have found them.

    It's a 26" A-Bolt with factory barrel, BTW.

    For Retumbo, I have settled on 89 grains. I have over 100 rounds of this load sent downrange already and it has proven to be the most accurate load ever fired from my rifle. Of course, I've improved the rifle since running out of my H870 load which I suspect may have done just as well in the rifle currently.

    In working it up I put four shots--87, 88, 89 and 90 grains all on top of each other into what would have easily been the best 100 yd group the rifle had ever fired. But at 91 I got an ejector mark and the shot flew wide. I didn't fire the 92 grain load. I guess that was sort of a "ladder test" right there and I wasn't even trying to do one. ES and SD are ridiculously low. Here's a 3-shot string: 2852, 2851, 2855....

    The only problem with this load--I chronographed it. 2853 fps. A full 125 below my old beloved H870 load. The velocity alone is enough to show up in trajectory but this time the trajectory seemed even worse than the velocity difference alone would indicate, which goes back to what I said in the other thread about BC's. In any case, a very accurate, safe load--but Retumbo is just too fast to be optimum for this bullet weight. It's giving up quite a bit of power.

    H50BMG: Color me disappointed. I didn't get a substantial pressure sign until 103 grains. I loaded a bunch up at 101 grains and accuracy was pretty poor. I only chronographed one at 2923. Loaded a bunch more up at 100 grains for an average of 2899. ES and SD the worst I've seen in a while (and that's with weighed charges). Accuracy was pretty mediocre.

    I've burned up nearly a pound of it and see no indications that it will approach the accuracy of the Retumbo load or the old H870 load. Maybe if I loaded it down to 2850--but then, what's the point?

    So I don't see myself bothering much more with this powder. Somethin' just ain't right about it. I noticed well before all the ruckus was made of it. Man, the recoil, the muzzle blast, and yes--the heat this stuff produced were just brutal. For only 50 damn fps? And groups nearly twice as big? Life is too short. I'll use something else.

    I do have some theories as to why this stuff occurs, and they do indicate those with longer barrels may have much better luck, but probably nothing I could prove in a court of law....

    And so I remember so fondly my H870 load. 99 grains for 2978 fps. I do think it was a little warmer than the Retumbo load but I could drop a grain and still beat it by a full 100 fps. And it was the most accurate load I had at the time. I suspect with the improvements to the rifle it would shoot right with the Retumbo load now.

    So damn. I'm thinking it's time for me to join the crowd and order up some WC872. Maybe it can be a suitable replacement. IMHO, neither Retumbo nor H50BMG are. Retumbo is great for 200's, 180's, etc. But for 240's I want my H870 back! I'm really hoping WC872 fills the void.