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7.62x39mm ammo tested in bbl lengths from short to long

Discussion in 'Rifle Country' started by R.W.Dale, Nov 28, 2008.

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  1. R.W.Dale

    R.W.Dale Member

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    Over on AR15.com I offered to compile a bunch of data concerning how 7.62x39 preforms in diffrent bbl lengths. I figured I'd share it with you guy's first.

    The rifles used for this test differed greatly from one another so please don't take this as "one size fits all" data.

    The rifles used were as follows

    1. A norinco 16.5" paratrooper SKS .310bore

    2. is a 20" Model 1 Sales AR15 upper .310bore

    3. a custom bolt gun with a 1/15 inch twist bbl that's 26" long and has a .308 bore

    All chrony readings were taken at 12 feet with a model F1 without sky screens against a uniformly Grey overcast sky and an air temp of 55 degrees. Perfect chronographing weather.

    Part 1 factory loads

    154 grain WOLF sp


    16' bbl........20" bbl........ 26" bbl
    2042............2106............2273
    2025............2110............2265
    2015............2113............2261
    2041............2125............2256
    2033............2124............2250

    avg velocity
    2031............2115............2261



    123 grn Monarch FMJ

    16' bbl........20" bbl........ 26" bbl
    2354............2432............2599
    2345............2418............2595
    2377............2405............2593
    2315............2453............2548
    2330............2422............2601

    avg velocity
    2344............2426............2587


    125 grn Remington SP

    16' bbl........20" bbl........ 26" bbl
    2265............2261............2428
    2238............2308............2444
    2202............2304............2437
    2191............2366............2485
    2224............2264............2486

    avg velocity
    2224............2300............2456


    Part 2 hand loads

    for these loads the 26" rifle was omitted and the SKS had the gas piston removed due to slamfire and cycling concerns

    170grn Sierra .308 diameter 30-30 flat point, magtech SR primer, 28.0grs H335

    16' bbl........20" bbl

    1921............1968
    1924............1967
    1931............1970
    1936............1970
    1896............1985

    avg velocity
    1921............1972


    125 grn nosler b-tip, magtech SR primer, 25.5grs AA1680

    16' bbl........20" bbl

    2256............2359
    2226............2355
    2243............2361


    avg velocity
    2241............2358



    The only real loser in all this is the anemic Remington ammo, this stuff just reinforces my assertion that anything METRIC factory loaded in this country is going to suck.

    The most interesting find was just how fast and accurate these loads were when fired from as accurate platform as possible through a 26" tube

    5 shot groups for the factory loads in the Stevens 200 were as follows
    154grn Wolf 1.2"
    123grn Monarch 1.37"
    125grn Remington 1.0"
     
    Last edited: Nov 28, 2008
  2. Winston_Smith

    Winston_Smith Member

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    Nice data. I just stocked up on some monarch from academy so this is nice data to have. The monarch looks to be pretty hot stuff. Thank for your efforts.
     
  3. jpwilly

    jpwilly Member

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    Rem is way underloaded! Curious why Wolf Military Classic Ammo wasn't also tested in 122gr or Winchester White Box from Wally World? Would like to have seen those included. Otherwise good info. Thanks.
     
  4. R.W.Dale

    R.W.Dale Member

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    Two reasons

    Even though I had a box of mil classic on hand my AR15 will not ignite the stuff.

    I didn't have any win ammo on hand, the ammo tested was what I happened to have.

    I'm most impressed with the Monarch fodder especially the combination of accuracy and velocity from the Bench gun. Just over MOA for less than $5 a box and at a smoking velocity too. I wish I had bought another 1K
     
  5. XD-40 Shooter

    XD-40 Shooter Member

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    With my Yugo SKS, which is a 24" barrel with the grenade launcher, I'm getting 2450-2500 fps with the 122 grain Wolf FMJ and I'm getting 2150-2200 with the 154 grain Wolf SP's. The extra 4" of length is giving me 75-100 fps. The grenade launcher acts like an expansion chamber, its not rifled, but it still contains the gas from the powder.
     
  6. Mike U.

    Mike U. Member

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    I've been hoping someone with a chrony and weapons in 7.62x39 with different barrel lengths would do this type of testing.
    Thank you, krochus. :)

    IIRC, someone mentioned in another thread that Monarch is a re-badged version of Sapsan. Anybody know if this is true?




    Hmmm...haven't been to Arfcom's dark side in a couple of weeks. Better mosey on over and catch up. ;)
     
  7. R.W.Dale

    R.W.Dale Member

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    All indication point to the stuff being rebranded Barnual, which is very good stuff
     
  8. gvnwst

    gvnwst Member

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    Nice data krochus. Can you get some ballistics charts up for this info?
     
  9. R.W.Dale

    R.W.Dale Member

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    I could calculate them up using my "POINT BLANK" program, but I'd be completely lost as to how to post em in a readable format. I really struggled with the HTML needed for this small collection of numbers.

    I'll see what I can do for a simple 100 200 and 300yd energy and trajectory table
     
  10. gvnwst

    gvnwst Member

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    Cool, thanks.
     
  11. R.W.Dale

    R.W.Dale Member

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    as best I can calculate the ballistics are as follows, based on a 200yd ZERO

    154 grain Wolf SP, ballistic coefficient .3302

    range........elevation........velocity........energy

    16.5" bbl

    100yds........+4.64"........1813fps........1124 fpe
    200yds........+0.00"........1614fps........890 fpe
    300yds........-17.78".......1432fps........701 fpe


    20" bbl

    100yds........+4.20"........1891fps........1223 fpe
    200yds........+0.00"........1685fps........971 fpe
    300yds........-16.39".......1497fps........766 fpe


    26" bbl

    100yds........+3.46"........2029fps........1407 fpe
    200yds........+0.00"........1811fps........1121 fpe
    300yds........-14.35".......1612fps........888 fpe



    123 grain Monarch FMJ, ballistic coefficient .257?

    range........elevation........velocity........energy

    16.5" bbl

    100yds........+3.44"........2042fps........1139 fpe
    200yds........+0.00"........1765fps........850 fpe
    300yds........-14.72".......1517fps........628 fpe


    20" bbl

    100yds........+3.12"........2118fps........1225 fpe
    200yds........+0.00"........1833fps........918 fpe
    300yds........-13.74".......1578fps........680 fpe


    26" bbl

    100yds........+2.66"........2268fps........1404 fpe
    200yds........+0.00"........1971fps........1061 fpe
    300yds........-11.71".......1701fps........790 fpe


    125 grain Remington SP, ballistic coefficient .267


    range........elevation........velocity........energy

    16.5" bbl

    100yds........+3,93"........1941fps........1046 fpe
    200yds........+0.00"........1684fps........787 fpe
    300yds........-16.15".......1454fps........587 fpe


    20" bbl

    100yds........+3.57"........2012fps........1124 fpe
    200yds........+0.00"........1747fps........847 fpe
    300yds........-15.02".......1510fps........633 fpe


    26" bbl

    100yds........+2.97"........2157fps........1292 fpe
    200yds........+0.00"........1879fps........980 fpe
    300yds........-13.11".......1629fps........736 fpe
     
    Last edited: Nov 29, 2008
  12. ByAnyMeans

    ByAnyMeans Member

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    Krochus:

    Did you see a big difference in your groupings when using 308 diameter bullets in the guns. I ask because I am looking into reloading 7.62x39 for my AK and it would be easiest and cheapest to use the .308 diamter I have for my .308 bolt gun. I heard everything from "it will be a tackdriver in the bolt gun and okay in the AK, hey it's an AK anyway who cares" to "if you do that you will blow your AK up in your face. You seem to be very knowledgable in this department so any info you could share would be appreciatted.
     
  13. R.W.Dale

    R.W.Dale Member

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    In all the .310 bored rifles I've tried .308 bullets in none showed the slightest reduction in accuracy because of it. Many reloading dies for 7.62x39 come with two expander balls for .308 and .310 diameter bullets just for this reason.

    I have however noted that with low pressure loadings the smaller bullets tend to produce somewhat lower velocities, but this disparity all but disappears when full throttle loads are used.

    many don't realize that .310 bores tend to have deeper rifling than STD american .30 caliber. guns. While the BORE may be .002" larger typically the measurement between the lands will still mic .300 just like any 30 cal. This means that you still have plenty of grip on .308 bullets in a .310 bore. I theorize that between the bullet jacket material displaced by the rifling and bullet obturation there's more than ample bullet seal generated to prevent any significant amount of gas blowby

    that or......

    when it comes right down to it .002 just isn't very darn much
     
  14. ByAnyMeans

    ByAnyMeans Member

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    Thanks for the reply and figured you were the one to ask. I never thought about the dies and your right all the ones I looked at had both 308 and 310
     
  15. Dr. Tad Hussein Winslow

    Dr. Tad Hussein Winslow member

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    Very interesting; thank you!
     
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