.244 mashburn Improved 30 degrees

Discussion in 'Reloading' started by longarm, Oct 22, 2013.

  1. longarm

    longarm Well-Known Member

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    I've been trying to get dies for.244 Mashburn Improved 30 degrees which uses a blown out 6mm Remington case with 30 degree shoulder. Redding can only supply dies for 6mm Remington Improved 30 degrees. Does anyone know whether these two are exactly the same or is there a slight difference? Thanks.
     
  2. longarm

    longarm Well-Known Member

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    Perhaps someone may have the case dimensions for the .244 Mashburn Impoved 30 degrees. The reamer print I have shows a shoulder width of 0.4358 which doesn't seem right to me as the body taper has not been improved much at all. So I am thinking the reamer print is wrong. Anyone with case dimensions please?
     

  3. Trickymissfit

    Trickymissfit Well-Known Member

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    I may be wrong, and don't have the book from Ackley close by. But it seems to me that he did two different cases. One used a shoulder diameter similar to what Ackley spec'd. And the other would have been closer to a standard case. I also think there is a difference between the neck lengths.
    gary
     
  4. longarm

    longarm Well-Known Member

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    I have also read that the .244 Mashburn Improved was the most powerful 6mm Remington case based wildcat tested, yet the chamber specs don't seem to back this up. Looking at the specs for the 240 Page Super Pooper, it has a shoulder width of .450 which reduces most of the taper and a shoulder angle of 28 degrees. So that is what I will get the dies and reamer for unless someone comes up with a version of the .244 Mashburn Improved that has a wider shoulder. Also, it seems that the 244 Mashburn is usually chambered with a very tight .262 diameter neck requiring neck turning which I don't want.
     
  5. Trickymissfit

    Trickymissfit Well-Known Member

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    there are several options to consider:

    * the age old 6mm Ackley Improved. Just a good round in everyway. You can take this reamer and make a 6mm/6.5x55 Ackley. Probably just as fast as the 57mm case. Of course you could do a .243 Ackley that would have the .35" 6mm neck length. You can't make cases out of .243 brass as the over all length will be about .110" longer due to the better neck design. Another option is the 6/250AI, but with the longer neck design. This one can be done with .243 brass, and will push a 105 grain bullet to 3000fps.

    * you should order in the finish reamer and reamer to cut the die blanks (which ever you decide). Many do this with a roughing reamer. I wouldn't let the tight necked chamber bother me much. They're usually a .264 chamber size, and a .262 die size or a .266 chamber and a .264 die diameter. Still remember that you have to order the reamer anyway, so you can also spec a no turn chamber.

    Might ask a reamer manufacturer if they have prints for the 6mm Arch. It's very close to the 6mm/55 Ackley (he actually never did this one, but did his own 6.5 case design)
    gary
     
  6. longarm

    longarm Well-Known Member

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    I'm building a 25 inch medium taper barrel hunting rifle using a Winchester Model 70 intermediate length action, so I have 3.0 inches in the magazine well. Being a hunting rifle as opposed to a varminter or target rifle, I want it to feed smoothly. That is why I am steering away from the 40 degree Ackley Improved chambers with their wide shoulders to 26-30 degree shoulders that are not as far forward and not quite as wide. I like the long neck and 26 degree shoulder angle of the 6mm Remington case, but it has too much taper. I am planning a 1 in 10 twist and will be starting off using the 95 grain Berger Hunting VLD. If that doesn't do well, then I will try 90 grain or even the 100 Sierra GameKings. The .243 case would be ok in a short action, but in an intermediate length action using only 90-100 grain projectiles, it just doesn't have enough case capacity, even in AI format. I expect about 3200 fps with the 100 grain projectile out of 25 inch barrel.

    I've just received the print for the 240 Page Super Pooper, and despite the stupid name, it seems to be about perfect. The neck/shoulder junction is 20 thou' below the neck/shoulder junction of the 6mm Remington, so I won't have any headspacing or fireforming difficulties using 6mm Rem brass. The shoulder diameter is 0.45 which is similar to the 6mm AI but not as far forward and with the 28 degree shoulder it should feed better. So it will have almost as much capacity as the 6mm AI but should avoid the potential feeding issues. The neck diameter is .277 at the top of the neck and gradually tapers out towards the bottom on the print so I won't have to turn the necks (I hope), even though the 6mm Remington is supposed to have a .276 inch neck diameter at the top and bottom of the neck.

    I asked for a finish reamer and was told that they can supply me with a "high speed steel" reamer. Is a "high speed steel" reamer a finish reamer?
     
  7. AZShooter

    AZShooter Well-Known Member

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    Your wildcat quest sounds interesting.

    High speed is a description of a type of steel often used in machining. This is going to be less expensive than carbide and should do an excellent job.

    Can I offer a couple of suggestions?

    I think you would be better served with a 1 in 8 twist which will allow you to take advantage the wonderful high BC 105 Berger hybrid. High Hunting results are trickling in. Did you see the results in SkyKing's post?

    Bottom of page: http://www.longrangehunting.com/for...er-takes-down-two-grizzlies-78901/index7.html

    The other idea is have Whidden make your sizer and seater dies. I own one of their FL/bushing dies and I give it high marks. When I need another custom die/die set I'll use them again.
     
  8. longarm

    longarm Well-Known Member

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    As the rifle is to be a normal hunting rifle, I can't see myself shooting much past 400 yards. I thought the optimum weight projectile in terms of flat trajectory vs wind-drift would be around 90 grains, with the 95 grain Berger a good choice. I thought the 105 grain would be better if I were shooting longer distances rather than up to around 400 yards. I use the 150 grain Bergers at 3300 in a heavy 27 1/2 barrel 270 Dakota for the longer shots. I will look up Whidden but will probably choose RCBS as they are slightly cheaper than Redding and both do dies for 240 PSP. Thanks for the response.
     
  9. Trickymissfit

    Trickymissfit Well-Known Member

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    high speed steel, refers to a completely different class of steel than we would normally be thinking of. It hardens a few points harder, and heat treats differently. High speed steel is what most drill bits are made of, as well as most reamers and end mills. What particular type is in vogue right now I can't say, but some common ones are Rex M2, Rex 95, Gorham Cobalt, Speed Star. Vasco Supreme is about as hard of a high speed steel as I've ever seen, and also the most expensive. A high speed reamer often will cut better than a carbide one, but will need resharpening a little more often.
    gary
     
  10. longarm

    longarm Well-Known Member

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    I just had a look at SkyKing's post and it is impressive. I've only shot one black bear at about 80 yards with a 250 grain Sierra GK out of my .338 Win Mag and I still had to chase it into the alders and finish it off with a headshot. With the pronghorn and the 243 AI, again I've only shot one at 348 yards with the .270 140 grain Accubond at 3400 fps and I had to shoot it twice before it dropped. But both of those instances were not good bullet placement. So far I'm very impressed with the performance of the .270 150 grain Bergers, it would be nicer if their BC was higher than .531.

    Thanks everyone for the info. on the high speed steel reamers.