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Barrel Length and Velocity

Discussion in 'Rifle Country' started by JustsayMo, May 6, 2006.

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  1. JustsayMo

    JustsayMo Member

    Oct 20, 2004
    the Evergreen State
    I have three Marlin 39's all with different barrel lengths. Golden 39A with 24" barrel, Golden 39A Mountie with 20" barrel and a Marlin 39TDS with a 16" barrel. I thought it might be interesting to compare velocities with a few varieties of ammo. I also tested some pistols with 5.5", 4-5/8" & 2" barrels to compare.

    Sunny, Breeze 7-18 mph, some higher gusts, quartering from rear. 65* F. Chrony Alpha master set up 12' in front of muzzle. Up to 15 shot strings. Listed fastest to slowest.

    FEDRAL 550 Pack 37g copper HP
    -Marlin 39A (39A) 24" barrel 1263 fps (averaged). Very good+ accuracy
    -Marlin Golden 39A Mountie (Mountie) 20" barrel 1254 fps Very good+ accuracy
    -Marlin 39TDS (TDS) 16" barrel: 1254 fps Very good Accuracy
    -Ruger Single Six (RSS4") 4-5/8" barrel: 1110 fps, Very good accuracy
    -Ruger Single Six (RSS5") 5.5" barrel: 1072 fps, Very good accuracy
    -Iver Johnson TP22 (TP22) 2" barrel: 961 fps, OK accuracy

    CCI Mini Mag 40g solid, copper
    -39A: 1255 fps, OK accuracy
    -Mountie: 1225, Good accuracy
    -TDS: 1221 fps, Fair accuracy
    -RSS5": 1067 fps, OK accuracy
    -RSS4": 1063 fps, OK- accuracy
    -TP22: 923 fps, OK accuracy
    Notes: This was the only ammo that the 5.5" Ruger Single six shot faster than the 4-5/8" barrel

    Aguila SE Subsonic 38g lead hollow point
    -TDS: 1007 fps, Good+ accuracy
    -Mountie: 994 fps, Very Good+ Accuracy
    -39A: 984 fps, Very good accuracy
    -RSS4": 923 fps, Very good Accuracy
    -RSS5": 901 fps, Very good Accuracy
    -TP22: will not cycle this ammo
    Notes: It was interesting to see that the 16" barrel produced the greatest velocity.

    CCI CB Long 29g Lead Solid
    39A: 677 fps, Fair- accuracy, VERY quiet
    Mountie: 675 fps, OK accuracy
    TDS: 668 fps, Good accuracy
    RSS4": 573 fps, OK- accuracy
    RSS5": 561 fps, OK- accuracy
    TP22: Did not test

    CCI Blazer 40g Lead Solid (20-30 years old)
    39A: 1230 fps, OK accuracy
    Mountie: 1203 fps, Very good- accuracy
    TDS: Did not test
    RSS5": 1012 fps, Good accuracy
    RSS4": Did not test
    TP22: Did not test

    Accuracy definitions; 25 yards for rifle, 25 feet for pistols.
    Excellent= 5 shot group covered by a tack
    Very Good= 5 shot group covered by dime
    Good = 5 shot group covered by a nickle
    OK = 5 shot group covered by Quarter
    Fair= 5 shot group covered by a Fitty cent piece
    Poor= anything bigger

    Other Notes:
    -The Chrony Alpha Master was easy to use. I had it set up within minutes the very first time.
    -The Marlin Mountie is my least Ammo finnicky of my rimfires. It seems to shoot everything at least OK.
    -The Marlin TDS is the most finnicky. Amazingly though it shoots the CB longs better than anything else I own. It must be a female.
    -The TDS also produced the highest velosity of the subsonic ammo.
    -I was suprised to see that the 4-5/8" Ruger Single Six usually produced better velocity than the 5.5" version. Cyclinder gap? tighter bore?
  2. 45crittergitter

    45crittergitter Member

    Sep 24, 2003
    It's commonly accepted that the .22 LR begins to lose velocity after about 16" of barrel. Of course, each lot of ammo and each barrel will vary....
  3. MachIVshooter

    MachIVshooter Member

    Aug 11, 2005
    Elbert County, CO
    I wouldn't say they loose velocity after 16", but the gain is so minimal that there is no reason to go longer other than sight radius. With various types of ammunition, very negligable average gains going from 16" to 22". Certainly not worth mention, since the standard deviation of rimfire ammo can easily be that much.

    CB's and the powderless aguila's, however, do loose velocity in longer barrels. The Aguila's are actually much faster out of a short handgun barrel.
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