Short Barrelled 7.62 x 51mm

Discussion in 'Weapons, Equipment & Rations' started by wellyhead, Aug 30, 2011.

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  1. Following on from the cut off SLR thread, has anyone any knowledge of, or insane opinions on, the effectiveness of a 7.62 x 51 mm rifle with a barrel 16 inch or less

    Is there a payoff on calibre vs length in respects to range ? Opinions on accuracy etc
     
  2. Generally, the shorter the barrel, the less accuracy at range.
     
  3. True but it's important to note that the length of barrel isn't directly responsisble for reduced accuracy at range it's that the reduced velocity from shorter barrels makes the round more prone to being blown off target and it will go transonic earlier which leads to a large and sudden drop off in accuracy.

    There is a widespread belief that longer barrels are more accurate than short ones but it isn't really true in simple terms.
     
  4. 16 inch is fine for most 7.62mm/.308 rifles, only if your after serious accuracy past 600 mtrs do you need anything longer.

    the basic rule is - barrel length gets you more velocity. barrel weight (big heavy tubes!) gets you more accuracy.


    the main problem with short barrels is more muzzle blast, and its closer to your ears.
     
  5. And for a given weight a short thick barrel will be more accurate than a long thin one.

    Which can adversely effect shooting, making the weapon appear inaccurate.
     
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  6. Shorter barrels also mean a shorter sight radius and therefore a drop in accuracy*.


    *Assuming that you are using iron sights of course.
     
  7. Not on the FAL/L1A1 orM16.

    --------------------------

    I've shot both the L1A1 with 21" barrel & para FAL with 17" barrel over a chronograph with the same SA surplus ammunition & the average drop in velocity was less than 70fps.
    Accuracy was better at 300yds with the para but it was wearing an Eotech vs irons on the L1A1.

    The shortest barrelled FAL I've fired was 14" plus a fixed brake to take it over 16"(US SBR reg's) & accuracy was definitely compromised on that particular rifle. Can't say the fall in accuracy was down to barrel length with a single sample though.
     
  8. You are right of course. I really shouldn't post before I've had my coffee in the morning.
     
  9. Not if you use ammunition that has been designed for use in that shorter barelled weapon, I presume.
     
  10. If range isn't an issue (eg urban <400m), 7.62 NATOs superior barrier penetration will make it worthwhile to use a sub-16" barrel
     
  11. I know the 5.56 v 7.62 argument rages supreme and I don't wish to dwell on all the intricacies too much, what I was looking at is wheter a short 7.62 could make up for the bullpup 5.56 over range. Now at battle distances, from what I am reading here, there is little differance in accuracy, my question is how they compare 400-600 ?
     
  12. what your trying to say is 'use faster burning propellents to be more efficient in shorter barrels'.................. and you get a huge jump in chamber pressures.

    Internal ballistics - Wikipedia, the free encyclopedia

    barrel length is matched to muzzle velocity, there is a min barrel length in any caliber where its no longer efficient in use of its propellent and a lot of the energy is wasted in muzzle noise and flash, ie- the M4 carbine.
    5.56mm has a higher velocity than 7.62mm and needs a longer barrel to efficiently use the powder.

    rough rules for this - 18 inch for 5.56mm at 3000 fps, and 16 inch for 7.62mm at 2600fps. any less than these and the FPS really starts to drop off.
     
  13. lets put it this way, the L129a1 sharpshooter rifle (which is an AR based rifle) with a 16 inch tube is still deadly accurate at 600 meters

    a 20 inch barreled AR(M16) in 5.56mm is really pushing it at 500 meters.

    whats needed is a family of gats in both 5.56mm and 7.62mm so the deployment can set itself up with one or the other or mix of both to suit the tatical requirment.
     
  14. jim24

    jim24 Book Reviewer

    The first Army to use the M16,AR15 was in fact the British who purchased 10.000 rifles in 1961, before even the USAF got them a few years later, at the time it was stated that there was no need for it to be used at any ranges greater than 400mtrs,
     
  15. trying to hit a fig11 at 300 with the M16a1 floppy brings out the best rifleman skills and the worst language from any soldier.