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Barrel Length & Velocity in 7.62x54R

Discussion in 'Firearms' started by Silversnake, Dec 29, 2012.

  1. Silversnake

    Silversnake Silverback


    Interesting study by a Florida engineering student looking a velocity as 2 inch sections of barrel were removed from a Mosin Nagant. Found it while considering the Ruger Scout Rifle because it only has a 16.5 inch barrel in .308. The Nagant only lost an average of 100ish fps from 20.75 to 16.75 inches. Acceptable to me.
  2. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    I'd be really interested in seeing if velocity increases with increasing bbl length. There has to be a way to harness that fireball. All the same, the loss is way less than I would have expected.
  3. BTPost

    BTPost Old Fart Snow Monkey Moderator

    Powder Burning Properties have a significant impact on Velocity, as well as barrel length. I wonder if the Student took those factors into account when he was doing his study, or just used one specific Cartridge Lot?
  4. Tikka

    Tikka Monkey+++

    He probably shot some surplus. ;)

    BT is correct, burn rate (fast or slow), primer and other factors have a definite affect as any reloader who owns a chronograph will testify.
  5. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    The kid said it was milsurp, 147 gr Bulgie. Can't help thinking that it was all the same batch in a spam can.

    Now, the fireball might be different with the different bullet, but I've a batch of 182 gr Bulgie that is not at all hesitant to belch fire from both the rifle and the carbine, and they are easily seen in broad daylight.
  6. BTPost

    BTPost Old Fart Snow Monkey Moderator

    Means that there is MORE Powder, that is burning slower, than the barrel can Hold, before the projectile exits.... Poor choice of Ammo, for that specific weapon.... Flare is BAD, for that reason... It demonstrates that there is unburnt Powder being spewed from the muzzle. The ideal situation for ANY FireArm/Cartridge combination, is to have just enough Powder, that it is completely consumed, and burnt into Gases, as the projectile exits the muzzle. No More, No Less.... and requires fine tuning the loading to a very fine detail. Burn Rate, Pressure, Powder Composition, Primer, Projectile Mass & Shape, and Barrel Length, all factor into these requirements... A very tricky calculation, that is most often arrived at, by Empirical Testing.... ......
  7. Tikka

    Tikka Monkey+++

    I am prone to agree with you.

    Is it unburnt powder? I've seen the floor sweepings from an indoor range burn. A quick flash burn, it is very similar to burning arty or mortar's excess charges.

    It sounds as if the Ruskies didn't care anymore about signature than they did their troops.
  8. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    If it is powder, it doesn't seem to survive the afterburner. But to tell the truth, I've never looked for it in the grass. I do know that firing them prone is apt to start a grass fire in dry conditions.
  9. Tikka

    Tikka Monkey+++

    Even if you did look, it would be difficult to see on grass.

    Expansion after the muzzle is wasted powder. As I believe it went smokeless around 1908 the case capacity wouldn't have been optimized for smokeless. Plus, it is loaded to be about the same as US 30 Cal.
    Starting fires is way too much signature.

    There are about 6-8 surplus loads for the 7.62x54R to choose from and a bud swears by Czech Silver point and a Yugo load.
  10. -06

    -06 Monkey+++

    Have a small amount of commercial Boxer brass that is easily reloadable. The fireball effect can be eliminated by proper powder loads. As pointed out the Mosin was originally a black powder or Cordite powered round which required more powder than modern rounds. Simply adjust your powder and the fireballs will disappear.
    BTPost likes this.
  11. Tikka

    Tikka Monkey+++

    True, due to case capacity probably a slow burning powder would be best. It would take experimenting (doesn't it always? ;) ) but easily possible.

    7.62x54R Russian @ www.reloadersnest.com

    And the good news is reloader's nest agrees with us. ;)

    As reloading a 45-70 with black powder is really super easy; I am curious how easy it would be with 7.62x54R

    I never could convince myself to use kapok and "fast" powder in pistols. ;)
  12. Legion489

    Legion489 Shining the Light of Truth

    Interesting read. There was a 300 fps drop in velocity from 28" to 16" (yes, OK, 28.75" to 16.75") and "only" a drop of 100 fps in the last four inches. 300 fps is actually a fairly large drop in velocity when dealing with effectiveness. Too bad he could include photos of the fire ball (called muzzle flash for those who want to attack me for not using proper terms) as at 16.75" it would be truly impressive. Even out a 20" carbine like the M-38 and M-44 the muzzle flash is quite imposing and can easily be seen from space at night in areas with out a lot of light pollution.

    If you are planning on using your rifle at night with a 16"-20" barrel you will need to plan on a large to huge muzzle flash out of any rifle sized cartridge that will tend to blind you and point out to anyone watching where you are. Personally I'm not sure that is a good trade off for the shorter, and admittedly handier, barrel length.

    The 7.62x54R was never a black powder cartridge and never used cordite. It was not, as Chick Blood, the ed of AMERICAN GUNSMITH claimed, a rimfire cartridge either. The 7.62 is the barrel diameter (.310"), the 54 is the length in mm, and the R means rimmed, like the .303 British and .30-40 Krag. The .30 Army (Krag) was the first cartridge loaded with smokeless powder in the US and never used black powder. The .30-30 was the first COMMERCIAL cartridge loaded with smokeless powder and never used black powder either. The .303 British originally used black powder (it was formed as a pellet and placed in the case and then the case necked around it, so it is nearly impossible to get the "proper" amount of loose black powder in a modern case, or a 1890's case either for that matter) and later used cordite. The Russians had their own smokeless powder plants and never used cordite, an English powder, in Russian made ammunition. The British .303 cartridge and Lee-Enfield (called a "Long-Tom" due to barrel length by the troops) was not finalized until very late December, 1888. If the committee had waited another few days, possibly as little as three more, it would have been finalized in 1889. The rifles and ammunition were not actually made until very late 1890 and the troops never saw any until 1891 (some source say 1892) and the whole army never had them until 1895 or so when the last of the old Martini-Henry rifles were turned in by British troops.
  13. Legion489

    Legion489 Shining the Light of Truth

    I was asked for sources as to the 7.62x54R and .303 Brit. NO military manual, COTW, cartridge collector's book or other source, even on the net, lists the 7.62x54R ever being loaded with black powder. Smokeless powder was in wide use at the time (1891) and England, America, Germany, Russia militaries were using it for all ammuntions.

    As to the .303 Brit being a black powder cartridge, this is well known and stated in many military manuals, cartridge collectors books and other sources. The book on the .303 Brit (don't have it handy to tell you the name, a quick web search will turn it up easily) talks about the cartridge being loaded with black powder and that the powder was formed into a pellet and the case necked down around it, as do early British military manuals, collectors books and other sources. There was a story on the .303 and it's history printed in the GUN DIGEST that also mentioned it as well. The reason was the early smokeless powders used by England eroded the rifling too quickly and they needed to change the type of rifling to a different type for use with smokeless powders. Cordite, made and used only in England, which is made as a long "stick", is also loaded the same way, the powder is placed as a bundle in the .303 case (if you pull the bullets from some of the large straight cased nitro powders you will see the powder is tied with silk string!) and then the case necked down. If the 7.62x54R is loaded with cordite, it was loaded in England as the powder was never loaded by any other country.

    All the above can be checked by dropping the NRA a letter and asking as well. If anyone has any information that contadicts the above, I would enjoy hearing the source and where it can be found. I hope this clears up any confusion.
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