New .338 lanches a 300gr Sierra MK at 3500fps?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Brent, Feb 14, 2002.

  1. Brent

    Brent Well-Known Member

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    Who wants the next level LRH cartridge? The latest and greatest are few and far between with the longrange large calibers and reaching a climax in possibilities I think. We all know the advantages that the added velocity would mean in wind etc. so....... What's it going to be that could reach the 3500fps mark with the 300gr Sierra MK and shoot very accuratly probably between 3400 and 3450fps in a 36" barrel? Can we make this baby happen? What's your Idea?
     

  2. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Hello Brent

    The 338/416 Rigby Imp will turn up 3310 FPS if I don't care about loading the brass more then 2X and that's with a 37" barrel.
    I have more case capacity but, not the powder available to use it. That could be a major problem in larger cases too.

    I think the 3400FPS is VERY feasable as I saw a freind of mine take his 338/416 IMP to 3350 FPS without any pressure signs but, he had a 40" barrel.

    So you see, you may not have to go too much bigger in case size to reach that 3400 FPS mark. I'm quite sure a slower burning powder and a 40" barrel will do it with the case I sent you witch has at least 8.5 to 10 grains more capacity then the 338/378 Weatherby case.

    What action would you put this case or larger one on????

    I have the Hall "G" on mine and it works fine. The BAT would be a fine one as would the Rock McMillen action.

    I'm sure it can be done (3400 to 3450FPS) but, is it really needed? That 300 gr bullet floats so flat and accurate at just 3200 FPS it scares you. It's like it don't want to come down. Check out the ballistics on it at that speed and then go to 3310 fps.
    The BC seems to run out at .797 as far as actual fire from the drop charts.

    You can always get more speed with longer barrels and bigger cases, to a point.

    Keep us informed as to your progress.

    Darryl
     

  3. Brent

    Brent Well-Known Member

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    I'm doin the dirty deed, as some say about using the Rem. 700 for the Rigby cartridge. I won't be loading it up too hot though, I want accuracy and long case life here. I've heard all the arguements for and against by now and can't say who's right or wrong. I do know, all those in favor have built many not just one or two, they are all accurate and have handled pressures that even ruined cases.

    I bought a Rem. 700ADL chromoly steel in 300WM ($395.)for fun until the 40" SS barrel gets here. $150. for the Choate stock. I'm kinda going the least expensive way I can with this one. The big Ruger action I have will work for the .408 Cheytac based .338 if I go to a larger case desighn. I can't afford a custom action right now so this will have to do. I have an Oehler 43 so I won't be guessing as to PSI being developed.

    I think the shoulder will be moved forward .050" to give about 140gr capacity up another 5gr. The taper in yours is .024" from base to shoulder. The reamer Dave, my smith has is .577" at the shoulder having .014" taper. That will gain some capacity, how much I don't know.

    I compared trajectories on the Oehler BEX program at 2975, 3200, 3300 and 3500fps, and what's gained at 3300 over 2975 is about what is gained from 3300 to 3500fps. Not as much as I thought but a substantial amount.

    Also on those two 338/416 Imp cases, one was perfectly tapered on the inside from .015" thick at the neck to .055" at the base, the other one was not. It went to .028" thick 2/3rds down from the shoulder and then sharply back to .020" thick then sharply back to .030" then onto .055" at the base. I measured them with an RCBS Casemaster dial indicator.

    I wonder which case would hold upto the heavy loads longer, the Weatherby or the Rigby. I assume the brass is just as strong as Norma makes both. The thing I like in the Rigby is it would seperate further up the case upon failure, I see this as a good thing. The Weatherby seems to get thin just ahead of the belt, I see this as a bad thing as there is nothing left to seal off the gas behind it if it lets go, the Rigby has 1/3rd of the case behind the seperation left to seal things off.

    BTW the case I measured at 134gr water capacity was the good thick one. OAL was 2.925".

    Oh Darryl, when you load yours HOT (3310fps) what is the first thing to go in the case, primer pocket, seperation 1/3rd up or just too damn tight anymore to chamber.

    Later
    Brent
     
  4. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Brent

    When they expand, they get to tight to chamber and the primer pockets loosen up.

    No seperation as you would see in other cases such as the 378 Weatherby.

    Good Luck
    Darryl
     
  5. Steve Shelp

    Steve Shelp Well-Known Member

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    Brent,
    Just a FYI to you. With a .577 diameter at the shoulder yes you will gain case capacity but that is really shallow taper and could cause extraction problems even without pressure loads. The rule of thumb that is normally used for minimum taper on a case is .008/in of taper. Anything less then that you normally end up tapping your bolt handle to get cases out of the chamber. If your smith already has the reamer, then I assume he's already chambered up some barrels. Ask him to make sure there are no problems that he is aware. There are no hard and fast rules here, only guidelines, so maybe you'll be ok.

    Also when you got 134gr of H20 with that case how exactly did you measure it? Just curious. I normally measure the case as fired, with a primer cup upside down, and fill even to the mouth of the case. Just comparing notes really. I've got (2) 338-378 Weatherby cases that I measured and they held 135.? and 136gr of H20 and they aren't improved at all and came out of a tight BR chamber.

    Steve
     
  6. Brent

    Brent Well-Known Member

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    Steve, I was comparing a case of my brothers in 338/378 which was 126gr water and a case of Darryls 338/416 Imp that was 134gr water. Derricks has a tight neck chamber and was not sized, Darryls was sized already so what it was when fire formed I don't know. Both had primers inserted upside down and a drop of soap to break the surface tension of the water (keeps it from rising above the case mouth). Both case were weighed before and after on a powder pro RCBS digital. I only weighed one case each and Darryls was definatly larger even though they looked very similar besides the shoulders. With what you say Steve I will check a few more of the 338/378's to see if it's a low one.

    Steve, any idea of case capacity in the improved 338/378 Weatherby? I'm guessing 140gr or so unless they neck down 460 brass to keep the necks long and then would they increase the case OAL even more also?

    Dave went hunting to Argentina yesterday, so I can't ask him about the taper issue for two weeks now. Darryl, will you measure a fired case of yours and see if there is a little less taper in those cases to make me feel a little better for now, maybe your sizer is a bit tighter than the reamer was.

    Ok I must say I am tossing around the idea of using the 338/378 case as is for a few reasons, the one Derrick has with the tight neck really shoots awesome. He has dies mounted in a Dillon 550 head that I can bring over and mount and use in mine for now. We can shoot the same ammo in a pinch if needed. His load development MAY help mine $$$$.

    I haven't had problems with brass on my 416wby yet, my 378wby showed a few hairline cracks above the belt on a few cases but I don't know how old those cases were, they came with the gun and were pretty used. I have come to learn by measuring belts on these cases where a load is getting stiff and killing case life, Cases aren't cheap.
     
  7. Steve Shelp

    Steve Shelp Well-Known Member

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    Brent,
    I'll double check the (2) 338/378 cases I have. Going by memory today. So I'll make sure but I'm positive they were in the mid 130's. I use the drop of dish soap also and right even with the top of the mouth. The sizing of the cases will make a +-1gr difference roughly, but not the 10gr difference we're seeing right now.

    Steve, any idea of case capacity in the improved 338/378 Weatherby? I would have to lay it out in AutoCAD and measure the volume increase. Will let you know. Roughly though my 338 Lapua Improvd is a 7% increase, and that shoulder was moved forward .050" and sharpened slightly. The diameters are very similar so that would be a rough guideline to go by.

    Nothing wrong with the 338/378 as long as your familiar with and aware of the belt issue with the Norma brass. You can always cut off part of the old chamber and rechamber later on to what ever you want. In the meantime you would be shooting a very potent case in the 338/378 and having a ball with the benefits you already noted.

    Keep in touch with what you find out about the H2O volume of your brothers cases.

    Steve

    [ 02-15-2002: Message edited by: Steve Shelp ]
     
  8. Brent

    Brent Well-Known Member

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    <BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Nothing wrong with the 338/378 as long as your familiar with and aware of the belt issue with the Norma brass. <HR></BLOCKQUOTE>What do yo mean Steve, anything I'm missing about the belt?
     
  9. Steve Shelp

    Steve Shelp Well-Known Member

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    Brent,
    You've just got to make sure you don't "stand on" your brass to much during the first couple of firings or the primer pockets will open up and you'll see some peening on the front edge of the belt. Some refer to this as the double belt. But you had made a comment above about watching the belt diameter and such so just keep doing what you've been doing and you'll be ok.

    This has always been a draw back when using any of the Weatherby belted cases which are produced by Norma. Norma cases are soft and it's easy to open the primer pockets up with normaly safe loads if your not careful. There's been many things tried to get around it. The best is to miniumun headspace the chamber and don't bump your shoulder unless you have to. Some have even gone as far as cutting the belt off the cases (tried it myself) but that wasn't a good solution either. It's the soft brass.

    In my 6.5-300 Weatherby, I switched to using WW Super 300 H&H brass and blowing it out rather than using the 300 Weatherby brass. The same load in 300 Weatherby brass open the pockets up in 3 or 4 firings, but I still have roughly (90) some out of (100) 300 H&H Winchester cases that I bought back in the early 90's and have been fired more than 4 times and those pockets are still tight enough to safely load and shoot again.
    You don't have that option with 378 brass obviosuly.

    Let me know if this didn't answer your question.

    Steve
     
  10. Brent

    Brent Well-Known Member

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    Thanks Steve,

    Can you buy the 416 Rigby brass from someone other than Norma? What I'm really wondering is which case is of a stronger desighn and by what MFG? Which case would you use?

    I know Lapua redesighned the Rigby case for added strength BUT, they shortened it too. I wish I could get the same speed from the Lapua brass, it is the quality I'm really looking for. I'm just afraid I would be pushing the PSI higher than I want to to get the velocity, been there done that and only found accuracy with one gun that way.

    Maybe I'm being a little to technical but this won't be cheap and I don't want to do it twice if I don't have to.

    Thanks for your help Steve,
    Brent
     
  11. Steve Shelp

    Steve Shelp Well-Known Member

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    Can you buy the 416 Rigby brass from someone other than Norma?
    Bell Labs might make the Rigby brass, but I'm not sure. I'm not aware of any others, besides Norma though. A couple of close friends bought some 404 Jefferies brass from Bell when RWS quite making the 404 stuff. All reports I heard was that it was absolute junk for any type of accuracy work. Wall thickness variations was several thousands of an inch. Guess you don't need much better for use in a double rifle to stop an elephant at 50yds though. So you can't blame them I guess.

    What I'm really wondering is which case is of a stronger desighn and by what MFG?
    Well for all out case capacity yes the Weatherby or the Rigby is going to have more room over the 338 Lapua as you already stated. But both brands are made by Norma so you have the softness issue to deal with. With the 378 brass you have the belt issue to deal with also. So based on this I would go with the Rigby over the Weatherby.

    Wonder if Darryl could give us an idea of how many loadings he gets on his cases using his standard hunting load that doesn't wreck the cases in 2 firings.?

    If whatever number he gives is suitable for you then go with the Rigby and have some fun.

    Which case would you use?
    Me personally... I would go with the tough 338 Lapua case improved more than what I have (there's room!!) in a long barrel and 3200fps should be easily obtainable. I know of a rifle with the same exact chamber I have (cut with the same reamer) and used 96gr of R25 without pressure and got 3165fps in a 45" barrel. I've used that same 96gr load in mine and got 2925fps average in a 32" barrel. I believe this barrel may be too long for this setup. maybe?? If you went with a 38-42" barrel using the slow burning powders you should easily end up over 3200fps. If not you could always use the R25 about stay jsut shy of 3200fps. That 86gr load of r25 i nthat rifle was shooting consistant 8" 10 shot group in competition and that was without a whole lot of load workup.
    You can't beat the toughness of the Lapua brass. My 338 Lapua brass also holds approx 1.5gr more water internally than my 338 Lapua Norma brand brass also. I've got up to 17 loading on a couple batches of cases in my 338 using Lapua brass. And some of it was shot in hot southern July/Aug weather when the bolt got sticky on opening. But I haven't lost a Lapua case from a loose primer pocket yet. Only 2 or 3 neck/shoulders cracking out of the original 100 cases. 3200fps with that 300gr bullet is very good! are you going to be able to match the 338/416 Imp 1 for 1... no. So I guess the question to ask, is that extra 100fps that is possible in the Rigby case really critical to you and your intended application? If yes then its the Rigby, if not then the Lapua would be my choice. IMO.

    I know Lapua redesighned the Rigby case for added strength BUT, they shortened it too. I wish I could get the same speed from the Lapua brass, it is the quality I'm really looking for. I'm just afraid I would be pushing the PSI higher than I want to to get the velocity, been there done that and only found accuracy with one gun that way.
    see my comments above. that 96gr laod of R25 at 3165fps was a safe repeatable load in that rifle. Yes I've seen that to many times of someone trying to make a rock bleed and it doesn't work. But in this case I think you can come very very close to the intended velocity with good accuracy based on the above info.

    Maybe I'm being a little to technical but this won't be cheap and I don't want to do it twice if I don't have to.
    I'll roger that. I've given all the facts I know, and some personal opinion above. Have fun selecting your new toy. That's part of the fun.

    your welcome. Let me know what your thinking in return.

    Steve
     
  12. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Hello

    I get 5 to 7 loadings from the 416 Norma brass when I cut the load down to 117 Grs from 122.5 Grs.

    Brent

    You would have had more capacity had I sent you a fired case instead of a full length resized one. It would have been about 12 more grains total had I not sized it over the standard 378 case.

    The 338/378 IMP Weatherby case and the 338/416 Imp should have the same capacity.
    The 33 Baer is the based on the 378 Weatherby case OR the 416 case. When improving them to the SAME deminsions they are both identical in capacity as stated by Bruce Baer who built mine.

    Later
    Darryl Cassel
     
  13. Brent

    Brent Well-Known Member

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    Thank you Steve, Darryl,

    Darryl,
    The 33 Baer, is that what the 338/378 IMP is? And your 338/416 IMP is the same without the belt, do I understand you correctly?

    Steve,
    my decission is now even harder, thank you very much. [​IMG] If you would, tell me about your ideas to improve the Lapua even more.

    The other two really have the case capacity over the Lapua so far, but the Lapua cases are much better, Hmmm when I'm all done I know I'll have one of each I just know it.

    5 to 7 loadings, uggg. I guess annealing wouldn't be an issue though. It would be nice starting over with new brass before necks get brittle. But I hate starting over with new brass. The wheels are turnin, and the brains on overload trying to weigh all this out.Thanks guys, I'll have to engrave your names on this when I'm all done for all the help your giving me. [​IMG] [​IMG]

    I'm goin to bed, I have to try the new Oehler 43 out tomarrow for the first time. [​IMG]
     
  14. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Brent

    Thant's correct.
    The 33 Bear is the same powder capacity when you imp the 378 Case to the 416 Imp case.

    The difference is, no belt on the 416 case and there is on the 378 Weatherby.

    You would have to do a lot of shooting to start out with say 100 to 200 cases and load them up 7X. Really not so bad considering how powerful these rounds are and how fast you can launch those 300 gr bullets.
    I am pushing mine and if you droped back a bit you could get more lkoadings per case.
    I run mine at NOW at 3200 FPS as mentioned before to save case life. When I go full tilt I have run it at 3310 FPS and that's when I only got two loadings from the cases.
    To make that bullet REALLY perform, it seems that you need to run it at least 3100 to 3150. Anything over that is icing on the cake and the bullet is MUCH flatter and performs on game much better. A longer barrel is a must to do it though.

    Later
    Darryl