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Thread: Discrepancies in load data?

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    Member AKsoldier's Avatar
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    Default Discrepancies in load data?

    I found some conflicting data today while putting together some .243 Win. with 85 gr. Barnes TSX and IMR 4350. According to The Lee Second Edition reloading manual, the starting charge for the 85 gr. Barnes X bullet using IMR 4350 is 43.2 grains, and the max load is 45.0 grains.

    Hogdon's website has conflicting data though. The same bullet and powder combo there is listed as a starting charge of 43.0 grs, and a max load of 47 grs. compressed.

    I'm not really concerned, since I've already done some load development with this combo and had no problems. I just thought it was strange, especially for a 2 full grain difference on the max load. I went with 45 grains, in case anyone is wondering. My last set with this combo was 44.5 grains and I felt I could bump it up a bit.

    Has anyone else run into conflicting load data like this?

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    Supporting Member iofthetaiga's Avatar
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    Yup. I find differences like that among different manuals all the time. That's the fun part of having many different manuals, you get to compare recipes, extrapolate, use your head a little bit. Check out the differences in the Barnes manuals. The data in the manual for the blue coated bullets was WAY more aggressive than prior or subsequent manuals. They really thought that blue coating was magic! STARTING LOADS in that book with those bullets resulted in cratered primers and a locked up bolt in my 338-06. The moral of the story is...
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    Quote Originally Posted by AKsoldier View Post
    I found some conflicting data today while putting together some .243 Win. with 85 gr. Barnes TSX and IMR 4350. According to The Lee Second Edition reloading manual, the starting charge for the 85 gr. Barnes X bullet using IMR 4350 is 43.2 grains, and the max load is 45.0 grains.

    Hogdon's website has conflicting data though. The same bullet and powder combo there is listed as a starting charge of 43.0 grs, and a max load of 47 grs. compressed.

    I'm not really concerned, since I've already done some load development with this combo and had no problems. I just thought it was strange, especially for a 2 full grain difference on the max load. I went with 45 grains, in case anyone is wondering. My last set with this combo was 44.5 grains and I felt I could bump it up a bit.

    Has anyone else run into conflicting load data like this?
    All the time. Differing chambers, differing barrels, various manufacturers of cases/differing lot #s by the same manufacturer, different lots of powders, etc. Changes to any or all of these things change the outcome of the load data.
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    Member GrizzlyH's Avatar
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    Only thing I can think, is they are testing loads in different firearms for the load data? Possible I guess.
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    Maybe I'm wrong, but I assumed the industry standard for testing was a pressure barrel. I wouldn't think there would be much variation there.

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    Quote Originally Posted by AKsoldier View Post
    Maybe I'm wrong, but I assumed the industry standard for testing was a pressure barrel. I wouldn't think there would be much variation there.
    Being new at getting back into loading, you got me on that. I haven't loaded in 40 years, but geared up to start. Good info to know though. Guess I'll compare all my data books before starting a set of loads for sure.
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    Quote Originally Posted by AKsoldier View Post
    Maybe I'm wrong, but I assumed the industry standard for testing was a pressure barrel. I wouldn't think there would be much variation there.
    Considering your example, Hogdon has a pressure barrel and Lee has a pressure barrel. That means two different barrels with different chambers. Pressure barrels are normally chambered to minimum specifications, but they will vary according to the age/use of the chambering reamer, skills of the machinist, individual specs of the rifle barrel, etc. Not to mention that the altitudes of load testing will vary as will the temperatures, humidity, moon phase, ad nauseam, ad infitum. Even if the load data was obtained in the exact same pressure barrel under the same conditions, using different individual lots of the same loading components (brass cases, primers, powder, bullets) will create contrasting pressure readings with identical charge weights, OAL, etc.
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    Supporting Member iofthetaiga's Avatar
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    Quote Originally Posted by 1Cor15:19 View Post
    Considering your example, Hogdon has a pressure barrel and Lee has a pressure barrel. That means two different barrels with different chambers. Pressure barrels are normally chambered to minimum specifications, but they will vary according to the age/use of the chambering reamer, skills of the machinist, individual specs of the rifle barrel, etc. Not to mention that the altitudes of load testing will vary as will the temperatures, humidity, moon phase, ad nauseam, ad infitum. Even if the load data was obtained in the exact same pressure barrel under the same conditions, using different individual lots of the same loading components (brass cases, primers, powder, bullets) will create contrasting pressure readings with identical charge weights, OAL, etc.
    Add to that some loads are not shot in pressure barrels, but a specific production rifle, which will generally be noted on the first page of the recipe in question, along with primer, brass spec's, etc. And, if not indicated, you can't assume that a given load was test fired at all. Some data has been computer generated and published without being test fired in ANY barrel...
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    1st Cor:I understand there will inevitably be differences, but enough to account for a 2 full grain increase on the max load? That can't be right. I'm thinking maybe when the Lee manual was printed IMR 4350 may have been a new powder and data has come out since that shows it's safe to push it harder than previously thought.....? I dunno.

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    Quote Originally Posted by AKsoldier View Post
    1st Cor:I understand there will inevitably be differences, but enough to account for a 2 full grain increase on the max load? That can't be right. I'm thinking maybe when the Lee manual was printed IMR 4350 may have been a new powder and data has come out since that shows it's safe to push it harder than previously thought.....? I dunno.
    2 grains is not that much discrepancy, I've seen that much and more difference (over and over) between various lots of the same powder.

    IMR 4350 was in use prior to WWII so its not been new in a long time.

    Max charges in loading manuals are simply a good guideline; they are certainly not holy writ. Reloading manuals suggest something along the lines of a 5-10% decrease from max as a starting loads and increasing judiciously to allow for various maximum charges in different rifles. A reliable chronograph will help establish if your loads are haywire by comparing your velocity with your expectations. Start low, work up slowly and measure your progress. I suspect you'll find your results will be safe, but that velocity will not be in line with the published results for that particular powder charge.
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    Quote Originally Posted by 1Cor15:19 View Post
    2 grains is not that much discrepancy, I've seen that much and more difference (over and over) between various lots of the same powder.

    IMR 4350 was in use prior to WWII so its not been new in a long time.

    Max charges in loading manuals are simply a good guideline; they are certainly not holy writ. Reloading manuals suggest something along the lines of a 5-10% decrease from max as a starting loads and increasing judiciously to allow for various maximum charges in different rifles. A reliable chronograph will help establish if your loads are haywire by comparing your velocity with your expectations. Start low, work up slowly and measure your progress. I suspect you'll find your results will be safe, but that velocity will not be in line with the published results for that particular powder charge.
    I've been loading for quite a while, this is just the first time I've found a discrepancy. I suppose it's because I'm rather poor in the manual area. I only have two - the Lee and a Lyman. Most of my data I have found online so I don't see the need to buy a lot of manuals. I can attest to the difference between rifles too. I remember loading some 165 gr. Speer hot cores in my .300 Win Mag. I used a charge of H1000 just about a half grain above the starting load and they wound up cooking out at over 3200 fps. I think the max load was supposed to be around that velocity.

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    Quote Originally Posted by AKsoldier View Post
    I've been loading for quite a while, this is just the first time I've found a discrepancy. I suppose it's because I'm rather poor in the manual area. I only have two - the Lee and a Lyman. Most of my data I have found online so I don't see the need to buy a lot of manuals. I can attest to the difference between rifles too. I remember loading some 165 gr. Speer hot cores in my .300 Win Mag. I used a charge of H1000 just about a half grain above the starting load and they wound up cooking out at over 3200 fps. I think the max load was supposed to be around that velocity.
    I think I have bought every load data manual that Sportsmans sells since last fall, knowing I'm getting serious about loading my own again. I spent a fortune (in my book) for RL-17 powder and am determined to make it work in all my rifle loads, even if not published yet by Alliant. I did some googling and found guys that have used 17 in non published loads yet by Alliant and it's looking good to me. It's still a matter of loading it to your specific gun and caliber in my opinion. Start small and work up to a satisfactory load. Hell, I'm 60 now and half crippled up, so if you don't hear back from me, I screwed up a load with RL-17.......LOL
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    I've got three 7x57's, three 358 Winnies, and three 257 Roberts. Each of them has a different max and chronoes differently with the same loads. And each has a "max" different than book max.

    Name of the game.

    I bet you could take two pressure barrels in a row off a production line and they'd give different results.

    Another name of the game.

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    Conflicting load data is normal for all the reasons listed and reasons we haven't even thought of yet. ALWAYS start low and work up. Do not ever start with anybodys max load and think it will be ok. There really are way to many variables, none of which can be exactly matched, to use the manuals for more than a starting point and which powder should give you the highest velocity.

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    AKsoldier:
    Them boys are right, all right.

    I'm sure, that in the future, you will run into Data from different manuals that are pretty far apart.

    One reason might be the way the DATA is presented. Some give it with a graph, and the velocities at the top. Others give just the figures. One helps to compare powders but may not be as exacting.

    I think that some of it may be Mathmatically Derived, but I dunno for sure.

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    Quote Originally Posted by Smitty of the North View Post
    I think that some of it may be Mathmatically Derived, but I dunno for sure.
    I've wondered about it, but the folks I used to know at Sierra denied it.

    One other point worth considering- Some of the old manuals still floating around and one still in print (PO Ackley) are downright dangerous if you go right to the max load listed. You can't even come close to getting some of his max charges into a case with drop tubes and the pressures will lock up a bolt and blow primers. Speer Manual #9 and earlier were almost as bad.

    I have no clue where they got some of their max charges, but they certainly didn't come from any firearm built on this planet.

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    Quote Originally Posted by BrownBear View Post
    One other point worth considering- Some of the old manuals still floating around and one still in print (PO Ackley) are downright dangerous if you go right to the max load listed. You can't even come close to getting some of his max charges into a case with drop tubes and the pressures will lock up a bolt and blow primers. Speer Manual #9 and earlier were almost as bad.

    I have no clue where they got some of their max charges, but they certainly didn't come from any firearm built on this planet.
    Are you implying that Mr. Ackley was an alien, or that you don't any guns previously owned by him?
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    I have an old Ackley book and volumes 1,5 and 13 from Speer. Some of their loads are just plain scary assuming you can even get the loads in a case. As Ackley was making his own chamber reamers, I suspect he was giving his chambers a long throat which drops pressures quite a bit. Where Speer got their numbers I have no clue,but some of their loads are actually more powder than you can get in a case.

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    When I first ran into this problem many years ago BTI (before the internet), I asked someone who had been loading a lot longer than me. Two bits of advice I still follow; "You don't start at the max load, you idiot!" and "The people who sell powder have no interest in you blowing up your gun with their powder." He didn't say 'you idiot' in the second part, at least not out loud.

    The first bit of advice means that the starting, or min. load, is safe. The second bit means that when in doubt, go with the powder company's manual over the bullet company's.
    This has worked for me over the years. Oh, and ignore loads in gun mags and now the internet.
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    Same O same O, start low and work up. About 9000 posts on here say that and I agree totally. Work up a load for your particular gun, starting low and work your way up. Chrono is good, but acurassy is the main outcome as long as your not showing stress on your brass after test firing. Find your spot, write it down, and live with it.
    I can do the impossible right away. Be patient, miracles take me a bit longer.

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