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Barrel Length and Velocity Difference

Discussion in 'Mossberg MVP Bolt Action' started by hombre243, Nov 20, 2014.

  1. hombre243

    hombre243 20g Premier Member

    Messages:
    665
    Good morning.

    Is there a source that can tell me how much difference in velocity there would likely be between the shorter barreled MVPs and the 24" models? I have never seen barrel length specified in the load books.

    Thanks in advance.
    h
  2. Water Monkey

    Water Monkey The man, the myth, the monkey Moderator Supporter

    Messages:
    3,760
    I'm sure there is but you will have to chrono your results based on your loads.

    But, depending on your use, the length in barrel shouldn't make much of a difference out to 300 yards
  3. nitesite

    nitesite Sheepdog Moderator "Philanthropist"

    Messages:
    5,515
    There are very loose "rules of thumb" estimates for every loss (or gain) of barrel length. BUT:

    What applies to rifles isn't always the same as for handgun length barrels. It is totally unpredictable unless you actually use a $125 chronograph to verify how your particular MVP shoots. It's not just the barrel length and chamber. It matters what powder burn rate, the distance the actual bullet is set off the lands before entering the rifling, the chamber dimensions, whether the case is neck-sized only (personalized for that individual gun) or is full-length sized (factory spec), the friction area of the bullet contacting the bore, the length of the barrel, which primer was used with what powder, if the bullet is a flat base or a boat tail, Factory ammo using non-canister powder or a handload, on and on and on and on and on..........

    Sorry, but there simply isn't a way to even remotely guess how your particular rifle will speed or slow a bullet's MV based on just the barrel length.

    All that said, most estimates for rifle barrel lengths say that you will see less than 50-fps increase/decrease for every inch gained or lost. But it is imprecise as hell.
  4. LAZY EYED SNIPER

    LAZY EYED SNIPER Overwatch Staff Member Administrator Supporter "Philanthropist"

    Messages:
    21,112
    ^ What he said.

    Ammo manufacturers usually list their test barrel lengths on their website with the load specs. That being said, their velocity specs are only true to the barrel they used, to the ambient temperature, elevation, and several other external factors at which the rounds were tested.

    In any case, difference in muzzle velocity between common barrel lengths is negligible as it applies to practical shooting purposes. You will likely experience as much variation in muzzle velocity using the same ammo in the same rifle on two days with varied temperatures. Only way to know for sure is to invest in a chronograph and compile your own data...
    hombre243 and nitesite like this.
  5. hombre243

    hombre243 20g Premier Member

    Messages:
    665
    Thanks guys. I didn't know if there would be much of a difference. Evidently not. I did a little searching and found an article at Guns.com. 'Splained everything perfectly. I do have a Beta Master Chrony. As soon as I get the rifle I will shoot a few and actually see what I am getting.

    As long as I can get close to load manual data that will be good enough. I noticed now that it was mentioned, Speer manual does give barrel length for the loads they put in the manual but there is no comparison of different barrel lengths. No need. Here's the link:

    http://www.guns.com/2012/02/16/the-myth-of-barrel-length-and-velocity-loss/
  6. nitesite

    nitesite Sheepdog Moderator "Philanthropist"

    Messages:
    5,515
    ^ What he said. :D
    hombre243 likes this.
  7. VitSports6

    VitSports6 20g Supporter

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    820
    John A. and hombre243 like this.
  8. hombre243

    hombre243 20g Premier Member

    Messages:
    665
    New post on old topic...

    I found that my MVP shot the crap out of the centers of many papers at 50-100 yards and velocity was never checked, and the loads were never chosen by velocity. They were worked up in my rifle and chosen for uniformity. By far the best load I encountered was with IMR8208. Somewhere between 24 and 25 grains. It did not matter what the temperature was. However it is a bench gun style and too heavy for this old fart to lug around hunting. I did find out too that meeting the factory velocity is not as important as finding the ONE or TWO loads my rifle likes and loading as many identical loads from same lot numbers of ingredients. I have a couple thousand 5.56 or .223 loads stored. I even loaded a couple hundred neck sized only just for S&G. Now that the weather is on the verge of clearing up...BTW it's FRICKIN SNOWING here...I will attempt to get all my new acquisitions sighted in and woods ready.

    It is by far my favorite rifle hands down.
    meanstreak and nitesite like this.
  9. Daryll

    Daryll .270 WIN Supporter

    Messages:
    277
    Generally its reckoned to be about 25-30 fps per inch... so the same load shot through a 20'' barrel will be about 100fps slower than from a 24'' barrel.

    Load data isn't always correct... while developing loads for my MVP in .223, I used Ramshot TAC and the load i settled on should have been pushing a 69gn SMK at about 2800fps, (according to Ramshot load data), but it was repeatedly chrono'd at about 2650fps.... and that was from a 24'' barrel, same as the load data.

    ... but its a tack-driver load (~0.3 MOA), so i'm not going to mess with it..!!
    meanstreak likes this.

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