exceeding book maximum length?

phlegethon

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  • Nov 4, 2018
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    How much does this matter? If I've measured the distance to the lands with the Hornady/Stoney Point tool, and I load to -0.020 based on that, but this ends up being significantly more than the OAL suggested for that bullet in the reloading manual, is that something I should worry about or not?
     
    I load 243 and 300WM well beyond book max length so I can use heavy/long bullets, worked up to a safe pressure of course. The one down side is my loads are manual feed only, but it works for my purposes.

    Mike
     
    SAAMI spec max COAL is for ammunition manufacturers to stay within so firearms and magazine manufacturers know what to design around and visa versa. You are safe.

    I measured my magazine interior length to know what my rifle max COAL is, then measured ogive to tip of a sample of bullets and subtracted three times the variance just to give me room for error and different lots and now just worry about controlling CBTO variation. I got lucky that max CBTO group size and .020" deeper give the same group size so I just target the middle and run with it. That puts me about 0.070" over SAAMI maximum COAL. I'm not worried. That max mag length still leaves a 0.080" jump. If I were willing to single feed I'd go that full length more.
     
    Loading manual max is generally set by the SAMII cartridge drawing. That is also the highest pressure. This then becomes a worst case.

    As you load out the pressure drops so you can load more powder to increase velocity.

    These long loads then become single loaded unless you are using a short body cartridge in a 308 magazine.

    David
     
    I load 308 long-ish. Like 2.860 in my mags.

    You can fit more powder, so work up slow. But I'm pushing my 308 pretty hard. I was at 45.2gr with no pressure signs, no hard lift. That's with a 178 eldm at 2712fps. But you gotta work up to the higher charges.
     
    The following is a general statement since the OP did not specify the bullet type or weight.

    If your recommended COAL is 2.8000” then it sounds like you have a long throat/leade which in essence give you a larger chamber. You should be safe and you will probable see lower velocities and probably lower pressures for a given load tested in a SAAMI chamber and barrel.

    If your recommended COAL is less than 2.700” then I would think you should consider following that recommended COAL.
     
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    The following is a general statement since the OP did not specify the bullet type or weight.

    If your recommended COAL is 2.8000” then it sounds like you have a long throat/leade which in essence give you a larger chamber. You should be safe and you will probable see lower velocities and probably lower pressures for a given load tested in a SAAMI chamber and barrel.

    If your recommended COAL is less than 2.700” then I would think you should consider following that recommended COAL.

    This. Granted you are following load data for that particular bullet.
     
    The following is a general statement since the OP did not specify the bullet type or weight.

    If your recommended COAL is 2.8000” then it sounds like you have a long throat/leade which in essence give you a larger chamber. You should be safe and you will probable see lower velocities and probably lower pressures for a given load tested in a SAAMI chamber and barrel.

    If your recommended COAL is less than 2.700” then I would think you should consider following that recommended COAL.
    Yes, this is what I was getting at. It’s not the COAL for the cartridge in general, it’s the specific bullet. This is the 129 gr Interlock SP that Hornady gave in their rebate. For that specific bullet, they recommend a COAL of 2.690, but at -0.020 I’m closer to 2.780. Even loading at or below their recommended charge, could this still cause problems?
     
    Yes, this is what I was getting at. It’s not the COAL for the cartridge in general, it’s the specific bullet. This is the 129 gr Interlock SP that Hornady gave in their rebate. For that specific bullet, they recommend a COAL of 2.690, but at -0.020 I’m closer to 2.780. Even loading at or below their recommended charge, could this still cause problems?
    no
     
    Yes, this is what I was getting at. It’s not the COAL for the cartridge in general, it’s the specific bullet. This is the 129 gr Interlock SP that Hornady gave in their rebate. For that specific bullet, they recommend a COAL of 2.690, but at -0.020 I’m closer to 2.780. Even loading at or below their recommended charge, could this still cause problems?

    No
     
    Just to clarify, leave .264” ( One caliber) of the bullet in the neck of the cartridge.
    That’s a good point. I’ll have to check that when I get home. I also wonder if their recommended length is because of the cannelure, which is well beyond the case mouth. But I’m not crimping so I’m not sure that really matters.