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Thread: Optimal Barrel Length

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    Member .338-06's Avatar
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    Default Optimal Barrel Length

    Can anyone tell me how you would go about determining optimum barrel length for a cartridge? Where velocity gain is greatest, before you get into diminishing returns. I know that many BPCR guns have +30" barrels, but is that really needed? I am asking in general, but specifically I'm interested in .300 Win Mag. Thanks.

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    Depends on what load you are shooting.

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    Member Big Al's Avatar
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    I really don't see that you give up that much going to 24" barrel on a .300 mag.

    Unless of course your shooting competitively. If your an F class shooter, then longer is better 30 to 32". But if your hunting, I just can't see how the extra fps will be worth the inconvenience.

    If we were talking about say the 6.5's then ever little bit helps, a lot.

    When the gain is less than 25 fps per inch. I really don't see the need to keep going longer, as a general rule.
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    Shooting a cartridge the likes of the 300 Win mag would achieve its highest velocity from a barrel of about 27 inches. With a little more powder to burn, such as 30-378 WBY or 300 lapua the 30 " will work better. For a hunting rifle that you'll need to carry this isn't very practical. The 300 Winny with a 24" will give up very little in field performance to the longer tubes and the practical portability of less barrel is of value. With that same volume of powder, as we go up in caliber we can use less barrel. Such as 22 or 23" on a 338, 20-22 on a 375, etc. The vloume of powder vs the volume of barrel gives us what is called expansion ratio and as that goes up (more barrel volume) we can get by with less barrel length. It is this expansion ratio compared to powder gas volume (how much of what powder) that gives us the optimum barrel length.
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    Member Dan in Alaska's Avatar
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    Personally, I like a rifle that has a great feel to it and balances well. I've been moving towards shorter barrels, as of late, because of their better handling characteristics. Velocity is one thing, but in a hunting rifle, handling is everything. I gladly give up a little velocity to gain some balance and better handling.

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    What Murphy said. A friend insisted on cutting his 300 Winnie to 18 inches for "ease of carry," in his own mind at least. Noisiest, flashiest rifle I've evern been near.

    He must have been a little suspicious about the results, because it took me more than 5 years to talk him into shooting it over my chrono. Noisiest, flashiest 308 Winchester you'll ever see.

    He'll still brag about the 300 Winnie as the ace number one all around Alaska rifle and snear at anyone who likes a 308 or even an 06. His version of the story is that my chrono is bum.

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    Member Dan in Alaska's Avatar
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    I did say that I'd be willing to give up a "little" velocity. Your buddy sounds a bit extreme.

    Most of my hunting rifles have 20-23" barrels, which is a little shorter than the usual 24-26" found on many factory rifles.

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    Thumbs up Optimal BBL. Lengths

    "Optimal" would be defined by the hands of the shooter and precisely what the individual is attempting to achieve. This is the part of the Outdoors Directory Forums that addresses Shooting (of all disciplines) - so not just hunting applications. I'll run with the shooting part first then talk a little shop with regards to hunting specifics.

    As your posting describes, the cartridge of discussion is the .300 Winchester Magnum.

    Like Murphy stated, a 26-27" barrel has routinely cooked out about the best in this class of case, primer, powder, and projectile host of recipes.

    Could you go longer? Well sure... nevertheless, where are the real world benefits to doing so at what cost?

    I agree and disagree with some other postings when it comes to everyday use or hunting. Handy, versatile, and fitting I do indeed find more favorable than every precious fps or ft. lbs. of energy we might achieve from an optimal bbl. length for a given cartridge. Could ya haul around that 30" bbl. .300 WIN MAG? Well of course! 10 ga. shotguns with 3.5" chambers, 30" barbells and a whole lotta gun metal still find a way into the fields! Musket muzzle loaders did not require wheels!!!

    Here's a couple of practical examples:
    With non-magnum & most magnum cartridges in bolt guns especially from say .243 to .338 --- I'll be hesitant to go under 20" bbl. unless given a special set of circumstances.

    Once I go the .35 to .375 calibers - I generally go 18"-20" barrels (as I see they give up very little real world ballistics). I'll relate that when I go with a shorter bbl. - it is about the carry length not about overall weight loss. In fact, I prefer a heavier shorter bbl. rifle configuration for these calibers.

    At the .416 to .458 calibers - I'll go 16.5"-18" barrels (again not sacrificing much in the form of real world requirements).

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    Member aksheephuntress's Avatar
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    Quote Originally Posted by Brian Richardson View Post
    "Optimal" would be defined by the hands of the shooter and precisely what the individual is attempting to achieve. This is the part of the Outdoors Directory Forums that addresses Shooting (of all disciplines) - so not just hunting applications. I'll run with the shooting part first then talk a little shop with regards to hunting specifics.

    As your posting describes, the cartridge of discussion is the .300 Winchester Magnum.

    Like Murphy stated, a 26-27" barrel has routinely cooked out about the best in this class of case, primer, powder, and projectile host of recipes.

    Could you go longer? Well sure... nevertheless, where are the real world benefits to doing so at what cost?

    I agree and disagree with some other postings when it comes to everyday use or hunting. Handy, versatile, and fitting I do indeed find more favorable than every precious fps or ft. lbs. of energy we might achieve from an optimal bbl. length for a given cartridge. Could ya haul around that 30" bbl. .300 WIN MAG? Well of course! 10 ga. shotguns with 3.5" chambers, 30" barbells and a whole lotta gun metal still find a way into the fields! Musket muzzle loaders did not require wheels!!!

    Here's a couple of practical examples:
    With non-magnum & most magnum cartridges in bolt guns especially from say .243 to .338 --- I'll be hesitant to go under 20" bbl. unless given a special set of circumstances.

    Once I go the .35 to .375 calibers - I generally go 18"-20" barrels (as I see they give up very little real world ballistics). I'll relate that when I go with a shorter bbl. - it is about the carry length not about overall weight loss. In fact, I prefer a heavier shorter bbl. rifle configuration for these calibers.

    At the .416 to .458 calibers - I'll go 16.5"-18" barrels (again not sacrificing much in the form of real world requirements).


    ...Just want to mention this awesome -handling, and performing gun we have...one of my favorites-

    -feels real nice, comfortable to shoot...and just a matter of knowing the ballistics of your gun, picking the ammo you want, and sighting-in accurately...most imp, though...knowing your ballistics-

    -it's a mod. 61 SAKO in the .338....barrel is real short...entire rifle length is only 40"....
    -nice negotiating the alder and Devil's Club down here on the Peninsula...


    ...-I think you would really like it, especially with your understanding and appreciation of overall barrel length...



    ...kind of messed - up picture quality...but a good representation of that SAKO .338- and I am 5'4"

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    Member markopolo50's Avatar
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    I wonder if the guys at Winchester, when they made the model 67, (22 short, long and long rifle) had the right idea when they made it with a 27" barrel?? This was quite a while ago, they started making them in 1934. Murphy, that was a real good explanation of barrel length. I see now why some of the bigger bore rifles come with 20 and 22" barrels. Thanks again.

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    Member .338-06's Avatar
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    I wasn't as clear as I could have been in my first post. I'm not asking about hunting, all my hunting rifles have barrels under 24". I guess what I'm asking is does anyone know a formula for determining where the velocity of a cartridge peaks inside a barrel. Or if not a formla, then how is the velocity peak discovered. Geez, that still isn't clear. We've all heard things like, "Shorten the barrel and you loose 100fps each inch". I'm trying to find out if there is a way to find out, other than through trial & error, when you stop gaining velocity due to barrel length or when the gains become less than 100fps to pick a number.

    Murphy, thank you for the 27" number and the expansion rate vs. gas volume explaination.
    Do you have a formula for this, or know where I can find it?

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    I am no expert in this field, by far. But just to add complication to your request, I do not believe that the answer you are lookin for is a simple formula or equation. Something not mentioned above, you have to consider powder burn rates. There are powders that will burn fast and give your cartridge optimal performance at say 22-23", when there are other powders that burn slow and will like a 26-28" barrel. If all things were set and remained constant, sure, you could develop a formula for acceleration vs. distance before drag, but you can totally skew those numbers by simply switching powders. (.02)

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    I guess it is a personal thing. I like the muzzle to be just a little heavy, so it follows the wood to the cheek. So make mine in the area of 26".
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