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Thread: 375 H&H Ackley Improved

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    Member hntr's Avatar
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    Default 375 H&H Ackley Improved

    Who has some loads with 270 Gr Barnes TSX?

    What powder?

    I can only find loads for standard H&H.

    Am I wrong to think to work up my load until I either get a sticky bolt or reach around 200 fps faster than regular H&H loads?

    Thanks

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    The 375 AI is very close to the 375 (not 378) Weatherby. You will probably get a sticky bolt lift before your get 200 fps over the H&H. With the 300 grain bullets you can get 2700 fps with 88.0 grains of RL-19. The lighter bullets would have no advantage especially since the improved case ups velocity a bit. H4350 may be a better powder for the 270 grain bullets and it will top out at about 86.0 with that bullet weight for about 2800 fps or so. If you have 375 Wby data start below that the data, the Wby case will hold more powder and you must reduce that load. The 375 JRS (Jon R Sundra) is a similar case in capacity also, the 416 Remington necked down to 375. You are in 375 Ruger territory and good country at that.
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    Member hntr's Avatar
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    Default 300 Gr TSX and IMR 4350

    So how about this combination Mr Murphy?

    Guy at hodgdon said the max is 5% over max for the parent cartridge which would only be 81.9 grains of powder using the IMR 4350. Is the 5% a good rule of thub for any of the AI cases?

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    Member Big Al's Avatar
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    Rule of thumb is to start at the starting load and work up. For get this 5% deal. Remember who's face and hands are hanging out in the breeze?
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  5. #5

    Default 375 ackley

    i have shot the ackley try 86 grains of imr 4350 behind the 270 barns i would bet you can move on up but do so with caution

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    The best way I know to work up loads is with a chronograph. Look for variations in velocity. If there is no gain in velocity or velocity actually goes down you are already passed max.

    I expect with the improve cartridge you could start with the max loads for the parent cartridge if you could not find any other data. I.E. start with 375 H-H max loads.
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    Quote Originally Posted by hntr View Post
    So how about this combination Mr Murphy?

    Guy at hodgdon said the max is 5% over max for the parent cartridge which would only be 81.9 grains of powder using the IMR 4350. Is the 5% a good rule of thub for any of the AI cases?
    The AI cases will vary a lot in capacity from caliber to caliber. I would fill a standard case with water and weigh it (after weighing empty) then do the same with an AI case. The difference in capacity of water % could then be applied to the powder charge by a factor of .8. Meaning that if it holds 5 grains more water, add four grains more powder than a standard listed load. This is a good place to start. (Do not put the water weight of powder in the case) I think the 375 H&H AI holds about ten grains more water than the srtandard case but you'll have to weigh it out.

    In some cases the 5% rule would be good in others not so good. There is a pretty big change in capacity of the H&H case when AI to a forty degree shoulder.
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  8. #8

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    I have the 375 Weatherby and a while back I tried 4350 with 270 grain Hornady's. Once I got to a certain point, velocity never inceased no matter how much powder I packed in it. Also no pressure signs. Could this be a case where it wasn't burning all the powder before the bullet exited? 24 inch barrel. 4350 works great with the 300 grain.
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    Quote Originally Posted by blackfoot View Post
    I have the 375 Weatherby and a while back I tried 4350 with 270 grain Hornady's. Once I got to a certain point, velocity never inceased no matter how much powder I packed in it. Also no pressure signs. Could this be a case where it wasn't burning all the powder before the bullet exited? 24 inch barrel. 4350 works great with the 300 grain.
    You reached the point where the loads were at maximum then went over that. Pressure signs or not.

    Pressure and velocity go up proportionately until a certain point where a one grain increase in powder increases pressure more but velocity less. If we keep going pressure will still go up but velocity will not. After this trouble awaits. This is my opinion based on some significant education in the field and a few hundred thousand rounds loaded for obscure calibers and wildcats as well as standard calibers. I 've run a lot of pressure equipment and this is the findings with the pressure sensors.

    On a practical note, rarely ever is all the powder burned before the bullet leaves the barrel.
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    Member L. G.'s Avatar
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    Quote Originally Posted by Murphy View Post
    The AI cases will vary a lot in capacity from caliber to caliber. I would fill a standard case with water and weigh it (after weighing empty) then do the same with an AI case. The difference in capacity of water % could then be applied to the powder charge by a factor of .8. Meaning that if it holds 5 grains more water, add four grains more powder than a standard listed load. This is a good place to start. (Do not put the water weight of powder in the case) I think the 375 H&H AI holds about ten grains more water than the srtandard case but you'll have to weigh it out.

    In some cases the 5% rule would be good in others not so good. There is a pretty big change in capacity of the H&H case when AI to a forty degree shoulder.
    The before-after procedure with water is a very good one that I suscribe to wholeheartedly.

    I just looked at the two in Mr. Howell's excellent reference. While he doesn't actually fill the cases with water, he computes the volume of the case in AutoCAD. (Volume to the external dimension - not internal.) I get a 6.8% volume increase to the Improved version.

    You'd be pretty safe with the 5% rule of thumb. I think the 257 Bob and 250 Savage are the biggest increases - close to 10%. .30-06 is the least "improvement" at about 2% volume increase.

    Excellent. Thanks for the clarification. Don't you just love that big blue book? I used the term displacement, which it is but you expalin it more better. I would say the 5% that he got from Hodgdons' Powder was well thought out, they take their work seriously. I did mean the various improved calibers show different %'s of gain and you cleared that up as well. Geez, I'm loosin it.....wait, maybe I never had?!

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    Default 375 ackley improved loading data

    i am also interested in any and all info on loads for the 375 ackley improved any info will be appreaciated. i have a friend who picked one up and cant seem to find any data on it. ty in advance for any info

  12. #12

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    I had a 375 Ackley Improved in the early 80's and loaded with H-870 it would yield about 100 fps over the H&H with 300 grain bullets.

    I have a couple of 375 H&H's now and toyed with the idea of reaming them to improved.

    I'd be interested in hearing what kind of performance people are getting these days with more modern powders.

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    The 375 Weatherby loads in the LAST (not the current one) edition of the Hornady load book work just peachy in the Ackly. As always - don't start at the top.
    Wasilly

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