Pistol cartridge lever gun barrel length: 16" vs. 20"

Discussion in 'Rifle Country' started by vincyr, Aug 23, 2016.

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  1. Llama Bob

    Llama Bob Member

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    Of course a longer barrel doesn't ALWAYS offer more velocity. To clarify, there are three forces on the bullet:
    1) pressure force (pressure x bearing surface) from the combustion gas behind it
    2) pressure force from the normal atmosphere in front of it (very small compared to peak chamber pressure)
    3) friction with the barrel.

    As long as 1) is bigger than 2) or 3), the bullet keeps accelerating. As the bullet moves forward, the space in the barrel behind it increases, causing the pressure for 1) to drop. When it gets to be less than 2)+3), the bullet will decelerate rather than accelerate.

    The whole point of Quickload is to accurately simulate this process so we don't have to wave our hands and guess about it. And having done so, we can answer the first of OP's questions: you'll gain about 50 ft/s with a 180gr bullet going from 16" to 20". Whether you feel that 50 ft/s matters is a separate question.
     
  2. Girodin

    Girodin Member

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    How is the buttstock any different between the two?

    I am not going to use a .357 on game outside of 200 yards and would prefer to be inside of 150. At those distances I do not see much difference in terms of either external ballistics or terminal ballistics.

    Sight radius assumes iron sights. I generally prefer to use irons though, not from a performance aspect per se, but because an optic spoils the aesthetics. Even when using irons I don't believe that advantage outweighs the handiness of the smaller lighter gun. I realize you can add a peep to both, but adding a peep gives the 12" gun an advantage over the 20" with buck horn sights. Again obviously you can add the peep to the 20" gun and have the advantage there.

    I'm not saying someone else has to make the same calculations, but actually using both guns, that is how I see it. I hand load and seek performance that is better than many anemic factory loads. That said, I am not trying to hot rod a .357 mag into a 30-30. If I need or want a true rifle round I will use one.
     
  3. bannockburn

    bannockburn Member

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    Having tried different barrel lengths in lever action carbines I have to say I really like the overall handiness and compactness of the 16" barrel model.

    001_zpseab50252.jpg
     
  4. Gordon
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    Gordon Contributing Member

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    I fooled with both lengths in .357 and .44 in the 80s and 90s and chronographed extensively my loads. I ended up keeping the 16" .357 Marlin and the 20" .44 mag. The amount of slow powder you can stuff in a .357 is just enough less than what a .44 mag holds that there is less than 100 fps advantage in the longer 20" .357 . A .357 MAX can use 20" but the regular .357 can't from my findings. The .44 maxes out in 20" BTW (I had a Remington 788 .44mag with a 22" and a roling block conversion with a 24" and there was no real increase in velocity) as it hold about 10 more grains of powder than the .357 does in heavy loads.
     
  5. CraigC
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    CraigC Sixgun Nut

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    Been there, done that. IMHO, they're neat guns but in practical use, I'll take the extra 4" of sight radius.


    Nobody said that but in this particular case, there is velocity to be gained above 16". The point is that folks think powder burning is what accelerates the bullet down the barrel. In reality, the powder is "burned" in a very, very short length. The expanding gases are what accelerates the bullet down the barrel. The bullet stops accelerating when the gases stop expanding, which happens long after the powder is "burned".


    You're referring to a 12" leveraction SBR then? I assumed the 12" .357 reference was a Contender.


    Yes, it does assume iron sights. Since we're talking leverguns, it's a safe assumption.

    IMHO, assuming iron sights, a 20" would have a huge advantage over anything 12". Sight radius, velocity, noise, muzzle blast, etc..
     
  6. CraigC
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    CraigC Sixgun Nut

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    Comparing different guns with different length barrels doesn't really tell us a lot. Any differences noted can easily be attributed to variations between guns. But I agree that there's no velocity to be gained over 20".
     
  7. Girodin

    Girodin Member

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    Exactly

    How many 12" SBR lever guns in 357 mag have you actually used? People can reach different opinions. I'm curious what use you are basing yours on.
     
  8. AlfonsDeWolf

    AlfonsDeWolf Member

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    Waterman, "at least 200-250 fps faster from 16" to 20" barrel"?!?! You said it, now show proof of that if you will.
     
  9. CraigC
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    CraigC Sixgun Nut

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    I don't have to have ever even handled one. Having owned 16" leverguns, I don't believe the slight and questionable improvement in handling is worth losing 4" of sight radius. I'm surely not going to give up another 4". As I said, I'll take the extra 4" or sight radius, decreased noise, decreased muzzle blast and increased velocity from the 20". Sorry but I bought into the short barrel fad early on but no longer drink the Kool Aid. Eventually, the novelty wears off. Which is why I'd rather have a 20" or even 24" levergun over a 16" or anything shorter.

    The only use where I can see a 12" lever having an advantage would be suppressed with an optic.
     
  10. stoky

    stoky Member

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    I had a 16" '92 that worked very well for me in 100yd competition. A big difference (to me) between 16" and 12" would be the requirement for fed.gov paper, unless the 12" was C&R............but still. :(
    I saw about 40fps/inch in .308 and .223 experimenting, but it doesn't seem like it would be that much in pistol cartridges.
     
  11. AlfonsDeWolf

    AlfonsDeWolf Member

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    Not meaning to hijack (probably am), what's a favorite new .357 lever gun recommendation?
     
  12. Redlg155

    Redlg155 Member

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  13. stoky

    stoky Member

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    It looks like it doesn't go longer than 18" for pistol cartridges (without perusing every sub menu layer), so it's not particularly relevant to the OP question. :rolleyes:
    There's a 3" barrel length in the table for .223 rifle. :what:
     
  14. Crunchy Frog

    Crunchy Frog Member

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  15. Redlg155

    Redlg155 Member

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    True...it does not publish the velocities for a 20" barrel, but it does show that the difference between a 16" and 18" barrel to be insignificant, thus you can expect the pattern to continue.

    What did surprise me is the velocity increase in the .223 from 3" upwards.
     
  16. CraigC
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    CraigC Sixgun Nut

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    You can't just look at 16" and 18", you have to look at the trend. Many loads will peak more than once. If you look at the 110gr load, it hits 1725fps in 12", then drops, then peaks again at 1790fps in 16", then dips, then rises yet again. BBTI would be a far better reference in this context if it went all the way to 24" and included more sporting loads. Rather than focusing on almost strictly lightweight self defense fodder. As it is, it is of limited utility. You can't really conclude that it peaks at any length without being able to see where it starts to fall off.
     
  17. AlfonsDeWolf

    AlfonsDeWolf Member

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    Thanks Frog, didn't know the Miroku rifles were still being produced. Very nice stuff
     
  18. 19-3Ben

    19-3Ben Member

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    Ok, I'm a little late to the party here, but I LOVE my Rossi M92 in .357mag, with 16"bbl.

    I can't speak to velocities because i don't have a chrono. I do have a buddy with a 20" model and we've compared them side by side. the 16" is a faster, more nimble gun due to less weight out front. The 20" has a very slight accuracy advantage due to increased sight radius, but if I get a skinner peep sight, I'm sure the accuracy would even right out.


    If I were hunting, and wanted something faster and more nimble to maneuver, as well was be able to change direction on a moving shot, the 16" would get the nod. It would also get the nod if I used it for HD (my M92 actually is my HD rifle). If I were competing, and knew that nothing mattered more than straight accuracy and I would be shooting from a fixed position, the 20" would get the nod.
     
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