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Thread: 357 mag velocity vs barrel lenghth?

  1. #1
    Boolit Man
    Join Date
    Sep 2009
    McCarthy, Alaska

    357 mag velocity vs barrel lenghth?

    I have only recently become aware that the 357 turns into a different animal when shot from longer barrels than the typical handgun has. Does anyone know at what length the velocity peaks in this caliber using 2400 burn rate powders?

    I have an Encore and wondered if a say, 14" handgun barrel would give up much to a 16 or 18".

  2. #2
    Boolit Master
    Join Date
    Feb 2006
    SW Washington

    barrel length

    I have never done a write it down comparison though I believe that more barrel length keeps increasing velocity with slower powders a lot. With H110 and 2400 a 24"shoots at least 100 fps faster than a 20". I have only had a chronograph for about a year and I still don't use it much. I am more interested in accuracy than velocity. A 14" barrel ought to get it going fairly well. Most of the uncounted thousands of .357 I have shot were fired out of a Ruger blackhawk with a 4&5/8"
    Barrel. I have a six inch S&W and a 20" carbine and a friend has a 24" rifle. I will have to get the chrony out someday when he is here and try the same ammo in three guns. Cylinder gap might skew results though.
    Besides that I went to the gun show today and found SR4759---------$160.00 eight pounds. Didn't want to spend the money. Maybe it will still be there in January?

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  3. #3
    Banned Bullshop Junior's Avatar
    Join Date
    Mar 2005
    Gonzales Texas
    I think is all depends on the load. What kind of powder you are using, what bullet/boolit you are using, and how what primer you are using, and so on. I don't think that there is one barrel length that will give top velocity with every load with every powder with every bullet. If you want that, you would have to have a custom barrel for every load that you shoot.
    I think what in a pistol about a 12" is as far as I would want to go. It may not give you the highest velocity, but once you go over that barrel length, it just does not seem like a pistol any more. I think the best compromise is the Marlin 94 lever gun.

  4. #4
    Boolit Master

    Shiloh's Avatar
    Join Date
    May 2006
    Upper Midwest
    If the powder is still burning, and gasses expanding, velocity should increase till it is consumed.

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  5. #5
    Boolit Master
    Join Date
    Mar 2008
    Just my opinion, and worth exactly what you paid for it...

    Most handgun loads are developed for far shorter barrels than yours.

    2400 will probably be an excellent powder with your 14 in. barrel.

    I don't know if it holds for longer barrels, too, but velocity seems to vary ~25-50 fps per inch added or subtracted from barrel length in the range of "usual", which is 2-6 in.

    The Speer handbook does have some loads listed for their standard length barrel, 6 in., I think, and some "short barrel" loads from a S&W 2 1/2 in., using the 135gr JHP.

    The velocity differences between barrel lengths are instructive, but probably not very useful for estimating velocity from a much longer barrel.

    It seems to me I have seen the information you are looking for in a reloading manual, but I can't remember which one. That might be a good place to start.

    Orrr...call the Alliant 800 number, and tell one of their friendly techs what you have, and see what he recommends. Good luck with your search!

  6. #6
    Boolit Master awaveritt's Avatar
    Join Date
    Sep 2009
    Central Texas
    My Lyman Pistol and Revolver Handbook, 3rd Ed. has an entire section devoted to the Contender/Encore type guns. Their 357 load with 2400 is:

    Lyman 358156 SWC starts with 10.6 gr. =1138fps Max is 14.0gr =1466fps.

    Sierra 158gr. JSP starts with 11.3gr. =1093 Max is 14.9gr.= 1491

    This is out of an Encore with 15" barrel. Hope this helps

    My old Speer #10 book has a 357mag handgun section (6" Ruger I think) and a 357mag rifle section (marlin test gun). The velocity difference between the two loads is between 400-500 fps.
    A significant difference, I'd say.
    Last edited by awaveritt; 01-14-2010 at 05:22 PM. Reason: text added.

  7. #7
    Boolit Man Jacko.357's Avatar
    Join Date
    Dec 2009
    Sth East Queensland Australia
    This link is worth having a look at. They conducted a study using a wide range of real world firearms not test barrels and have data indicating velocity obtained for a number of commercially available pistol / lever cartridges in firearms with widely differing barrel length's.

    Last edited by Jacko.357; 01-16-2010 at 07:57 AM.
    "To my deep mortification my father once said to me,'You care for nothing but shooting, dogs and rat catching, and you will be a disgrace to yourself and all your family."'

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  8. #8
    Boolit Master

    GP100man's Avatar
    Join Date
    Jul 2006
    Southeast, NC (Coastal plains)
    Another 2 cents

    My findings with revolvers meets snipers remarks , Ive run 2, 3,4 & 6" 357s over my chrony & found the gain with the same ammo very close to 50 fps gain / inch .

    In a 14" or longer I`d probably be looking at IMR4227 /SR4759 powders .

    IMR 4227 is good in revolvers but ya just can`t get the speed that H110 offers .

  9. #9
    Boolit Master
    Join Date
    Apr 2005
    Kansas US of A
    IMHO this has gotten turned 180 degrees from originall question and issue. You can't really compare a revolver to a break action or lever gun can you? I suppose but it is not on equal ground.
    Rickk, step over to the LASC webiste and have a look at some work with the 357 mag in an FA. Uh and I know that goes against my above comment, but most FA's are comaparble to a good rifle. I used and worked up to one of the loads mentioned there. It was one of the better loads in the FA and worked even better in the TC. It is a MAGNUM, so if you don't like recoil don't even look at it.
    I have a RCBS 180 sil bullet with a lilgun load and it will do right at 1700 out of my 10" barrel.
    Lilgun has gotten some bad press in wheel guns but I see none of it in the TC.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check