.240 Incinerator ?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by DIRTY 30 RUM, Dec 28, 2007.

  1. DIRTY 30 RUM

    DIRTY 30 RUM Active Member

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    A friend of mine is wanting to build a hot rod 6mm. I saw this load data on reloadersnest and thought it might be a little far fetched. Nosler Ballistic Tip
    BulletWeight 70 grs
    Powder IMR 7828
    PowderWeight 74.5 grs
    Primer Winchester LRM
    Brass Make Winchester
    Barrel Length 28.5 (inches)
    C.O.L (inches)
    Velocity 4400 fps
    And the 55 grn Noslers are going 4680 With IMR 7828. It seems to me that the powder would be to slow for that light of a bullet. I know on my 257 Wby mag that slow of powder just makes a bigger fire ball. I was thinking of a 6mm WSM anyone have one. BTW the 240 Incinerator is a 264 Win Mag necked to 6mm. 35 degree shoulder and minimal body taper.
     
  2. Joel Russo

    Joel Russo Official LRH Sponsor

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    Buffalobob and I both shoot the .240 WBY.
    I have mine on a diet of 49.8 of RL 22 with a 105 Berger. 3380 fps in a 28" barrel with exceptional accuracy. I'm not sure of the powder he's using, but he is using the 115 gr Berger with the same crazy accuracy.
    Chime in here BB.
     

  3. DIRTY 30 RUM

    DIRTY 30 RUM Active Member

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    Do you guys run the factory free bore in your barrels. I was thinking of re barreling my 257 WBY with a 28" to take advantage of the big case.
     
  4. Joel Russo

    Joel Russo Official LRH Sponsor

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    No freebore for us. :)

    Mine was chambered by Clarence Hammonds, and Buffalobob's was chambered by Clay Spencer.

    I have a 28" Hart barrel and I think his is a Spencer at 30".
     
  5. Buffalobob

    Buffalobob Writers Guild

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    I run 51.0 grains of RL 22 with a Fed 210GM primer and the 115 Bergers jammed in a 30 inch barrel. The load is very hot and cannot be used in hot weather. You may not be able to get tht high in powder load. It is just death and destruction on antelope at long range. Of course antelope hunting is not high volume shooting so the barrel seldom is allowed to get hot. The chamber is "minimum SAAMI" so it is tight and the action has been trued.
     
  6. DIRTY 30 RUM

    DIRTY 30 RUM Active Member

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    BB what do you think of a 6mm WSM or SAUM. With a 28"-30" tube, it would seem that you could push a 115 fast for some "death and destruction on antelope at long range". BTW the 257 With a 87grn does wonders on white tail @ 300 on in.
     
  7. Buffalobob

    Buffalobob Writers Guild

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    I am not familiar with the 6 WSM or SAUM. I have shot the 240 Wby cartridge for about 20 years and with a 85 grain Speer or Barnes X in a shorter barrel it is a very nice eastern whitetail cartridge. Case capapcity of the 240 Wby is about the same as the 6-284 or 6-06 and caseheads are all the same. Most people opt for the 6-284 because they believe you get better brass. Admittedly Norma brass is soft but it is high quality and I only shoot antelope once a years so it is not a big expense to me to lose a few pieces.

    Kirby Allen and some other knowledgeable people expressed reservations about 1-8 twist barrels at high speed because they tend to blow up bullets. They suggested a 1-9 barrel. I have a 1-8 and so far everything is fine but I just shoot that one bullet.

    I also have a fondness for the 257 Wby and think it is a nice case.
     
  8. malcarjeb

    malcarjeb Well-Known Member

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    I have a 6mm WSM and its fun to shoot. I use mine mainly for whitetails with an 85gr Barnes XLC. It has a 29" 3 groove 12 twist Pac-Nor barrel and shoots the XLCs at 3850! It shoots the XLCs so well I haven't tried anything else in it.
     
  9. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I build alot of big 6mm rifles for varmint hunters, big game hunters and longrange shooters. Everything from 6mm BR up to the 6mm-06 AI.

    I can tell you without a doubt, if your going to be shooting lightweight bullets, by that I mean 75 grains or less, the 6-284 is damn near about the largest capacity you want to use. That class also includes the 6-06 and 240 Wby in the same capacity class.

    I had a customer bring in a 6mm Mach IV which is the 264 WM necked down to 6mm and shoulder angle sharpened slightly. He said the barrel was shot out, it was not, just severally copper fouled, after three days of cleaning on the Foul Out electronic bore cleaner, the barrel was clean. The rifle was not overly accurate so the customer asked if I could try to work up a load for him, for yotes. I have long sence forgot the exact loads but I know for a fact that this rifle(28" barrel, 1-10 twist Shilen) did not break 4100 fps with the 70 gr Ballistic Tip and that was a top load and accuracy was only around 1 moa. Now I am not saying thats the fault of the chambering because the rifle was not accurized or anything special, just fitted with a new barrel.

    The bad thing was extreme spreads were in the 100 fps range with the 70 gr bullet.

    Best load I came up with accuracy wise was with the 95 gr Ballistic Tip and Rl-25 at that time. Again, I do not have the load data but the velocity was in the 3800 fps range with its best load which averaged right around 1/2 moa with spreads in the 30 fps range.

    Now, that is faster then a 6-06 AI will drive the 95 gr BT for sure but the lighter weight bullets, you can push very close to 4000 fps with a 70 gr BT in a 6-284 with this length barrel. Maybe not breaking it but damn close so yes the 6mm-264 will add 100 fps or so to the larger 6mms on the 284, '06 or 240 Wby case but thats about it.

    With heavier bullets, it will have a greater advantage but still, you get to the point of diminishing returns. You will still gain velocity to some point in capacity but it does not stay proportionate to the amount of capacity increase. Then once you reach a certain point, you will actually experience a loss in velocity when the capacity gets to large.

    Personally, I have studied and worked on building a 6mm Allen Magnum and I have yet to see a combo that really offers that advantage over the 6-284, 06, 06AI or 240 to the degree that it would be worth while to invest on the new cases design.

    Of the designes I like the most, I was going to use the SAUM case, set the shoulder back very slightly, and then trim the neck to be roughly .300" in length. Capacity would be slightly less then the SAUM case but still more then the standard big 6mm.

    No it would not be as large in capacity as the 6-264 but it would be more practical and I would be amazed if it did not equal or exceed it in performance.

    The main reasin I did not do this, the life of the SAUM is very uncertain at this point. If they were selling like hotcakes, there would be a 6mm AM based on this round. There still may be but I have other projects in the works that are more pressing.

    In any big 6mm the size of the 284 and larger, your really fighting a loosing battle if you are using bullets lighter then 95 grains. +100 are much better and 105s and larger are even better. Working up a load for the heavy 115 gr Bergers or some of the really heavy Wildcats would work even better.

    You hear all the time about these guys getting ultra high velocities, when they are pressed on it, generally, for accuracy, they either drop velocity dramatically with the light bullets or switch to a heavy bullet with these large capacity small bores.

    By the way, powder bridging can be particularly serious with the 6-264 WM improved type rounds, ball powders are still the best. With the 284, 06 and 240, these are not needed as much, with the sharp shouldered '06 AI, it can also be a problem with some of the more aggressive stick powders.

    Kirby Allen(50)
     
  10. Wild_Bill

    Wild_Bill Well-Known Member

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    Short Action

    Hi if you want a short action look at the 6mmX55SMc. I am building one for FClasx open it will be my short range rifle. 56gr Retumbo will get 3300fps+ with 107gr Sierra MatchKings. that is the starting load and because of the case shape and using Retumbo it has verry good barrel life. the case holds 55gr water to thd base of the nech their are 2 versions one on the Rem SAUM case and the other on the WSSM case. I have my reamer ground for the Rem design but have increased the shoulder and base by .003" to use Norma WSM cases if Norma manufactured Rem SAUM cases were avai able here I would have used them but they were only made for the US market.

    Cheers Bill
    Australia
     
  11. malcarjeb

    malcarjeb Well-Known Member

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    I have not had any problems with ES or accuracy with med. weight bullets for cal. The 6mm WSM has been extremely accurate and not picky at all. I just use Kirby's recommendation of ball powders in all my very overbore rifles.

    Kirby I wonder if maybe being closer to sea level would explain why I dont have the problems you have talked about with overbores and light to med. bullets for cal. I am about 130 ft above sea level and I'm sure you are a lot higher than that. I was just thinking maybe the heavier pressure of the atmosphere helps it work better.(Hope this is not too crazy) I just have not had any problems even with the 6.5 RUM with light bullets. Shot some yesterday at 700 yards. Most groups were in about half MOA at 700 and a nickle will cover the groups at 100 using Barnes XLC 120's. I even loaded some 120 Nosler BTs and they shot pretty much one hole groups at 100 and ES around 6 to 7 with a muzzle velocity of 3838 ave. I haven't had a chance to try them a 700 yet.

    I am no expert and don't why I just have not had any problems at all with accuracy or velocity.
     
  12. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    When I say lightweight bullets in the 6mm bore, I am referring to bullets in the 75 gr or lighter weight ranges, similiar bullets in the 6.5mm bore diameter would be something like 85 grain bullets or lighter.

    A 120 gr bullet in the 6.5mm is certainly not what I would consider lightweight, its a middle weight bullet. I am sure this is why you are seeing good results. I have never said that lightweight bullets can not be accurate either.

    In my 257 Allen Magnum, I get the 100 gr BT up to 4100 fps and groups in the 1/2 moa range at 500 yards with my medium weight sporter rifles. Extreme spreads are generally in the 30-40 fps range. Drop in a 130 gr Wildcat and those extreme spreads drop to 20-30 fps and groups at 500 yards drop to 1.5 to 2" groups in good conditions.

    Jump up to a 156 gr ULD RBBT and velocity spreads will drop to the high teens to 20 fps range and groups will often even tighter then the 130 gr loads.

    That is my point, the heavier the bullets in large capacity rounds, the easier it is to get them into tight groups at long range and result in smaller velocity spreads.

    Again, my defination of lightweight bullets was misunderstood or not defined for 6.5mm bullets, Anything less then 100 gr in the 6.5mm, I would consider lightweight bullets, espeically for the capacity your using. Now if you were talking about a 6.5-06, 100 gr would not be overly lightweight.

    Its all relative to bore diameter and case capacity.

    Most any quality bullet can be made to shoot well in any capacity, that does not mean its the best bullet for a specific application. Generally with large case capacities in small bores, heavier is better.

    Kirby Allen(50)
     
  13. DIRTY 30 RUM

    DIRTY 30 RUM Active Member

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    repeat
     
    Last edited: Jan 2, 2008
  14. DIRTY 30 RUM

    DIRTY 30 RUM Active Member

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    Ok not to beat the 6mm to death but what about the 6mm WSM for the 105 and up Bergers. Fifty I under stand what you a saying about the large case with light bullets. I have played with 110 V-MAXs out of a RUM, & 75 grn out of the 257 WBY. It would seem with Retumbo or RL25 type powders you could get a 115 to run pretty flat.