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Thread: .308/N140 very smokey

  1. #1

    .308/N140 very smokey

    Tikka T3 Lite, .308, 20" barrel with Atec Maxim mod.
    load:
    Sako brass. Full resize once fired.
    Powder N140.
    Bullets. BT 150. Amax 155.
    primer. Federal 210
    i made some loads using the above, starting from 42.6. 43.1. 43.6.
    The loads shoot well enough but a lot of smoke after firing each round. Also the neck before the shoulder is quite dirty.
    I thought Vhit powder was a clean burning powder.
    I use the loads mainly for stalking with a bit of practice on the range.
    has anybody had similar?
    Thanks
    Norm

  2. #2
    These charges are too low. Yes, I know they're in line with Viht's data, but that's notoriously conservative for 308 Win for some reason. Work up in small steps, 0.3 or 0.4gn. You should be able to exceed 46gn comfortably with the 150, and 45.5-46.0gn with the A-Max. Note that the 155gn A-Max produces higher pressures than most other 155gn match bullets which can usually take another half grain charge weight.

    Increased charges and higher pressures will increase the burn efficiency and produce a bit less smoke, but you'll always get some especially with a 20-inch barrel. The amount of fouling on the neck / shoulder is partly a powder issue, but is very much determined by the case to chamber fit and speed of obturation after initial ignition. You may be setting shoulders back a bit too far if full-length sizing using the default die setting with the die body in hard contact with the shellholder. the ideal set-up pushes shoulders back by two to three thou' (a mere one thou' in match rifles) - enough to ensure 100% reliable chambering, but with minimum shoulder to chamber clearance. Fed 210 primers are generally regarded as 'warm', so should be fine for rapid ignition and initial charge burn, but a primer change may help. Don't use Magnum primers in the 308 though.

  3. #3
    Also have a look at the thread that I started 'Blackened Cases'. The revelation for me was twofold. Firstly to set the bullet deeply and secondly to use a Lee Factory Crimp die.
    I can also confirm that the current Vihtavouri loads are conservative. They have been reduced substantially in recent years.

  4. #4
    I use 44.5grs behind 155gr smk which are really good

  5. #5
    Think they are going 2800fps

  6. #6
    pulled this off as i shall be trying it soon, as i use h4895 at this time but we know that sorry

    Enlarge table (new window)

    .308 Winchester

    Test barrel: 610 mm (24), 1 in 12 twist
    Primers: Large Rifle
    Cases: Lapua, trim-to length 51,00 mm (2.008)

    Bullet Powder Starting load Maximum load
    Weight Type Mfg C.O.L Type Weight Velocity Weight Velocity
    [g] [grs] [mm] [in.] [g] [grs] [m/s] [fps] [g] [grs] [m/s] [fps]
    9,7 150 HPBT Sierra 71,0 2.795 N140 2,62 40.4 752 2467 3,06 47.3 869 2851
    9,7 150 Mega Lapua 65,2 2.567
    N140 2,35 36.3 715 2346 2,95 45.5 824 2703
    9,7 150 SPBT Sierra 70,0 2.756
    N140 2,71 41.8 767 2516 3,05 47.1 858 2815
    9,7 150 Lock Base Lapua 70,0 2.756
    N140 2,75 42.4 800 2625 2,90F 44.7F 853 2799
    10,0 155 HPBT Sierra 71,0 2.795
    N140 2,40 37.0 717 2354 2,86 44.2 827 2712
    10,0 155 Scenar Lapua 71,0 2.795
    N140 2,38 36.7 686 2251 2,81 43.4 807 2648
    10,0 155 Scenar SJ Lapua 71,0 2.795
    N140 2,66 41.0 767 2516 2,95 A 45.5 A 855 A 2805 A
    1) A muzzle velocity exceeding 1000 m/s ( 3300 fps) may lead to severe barrel fouling!
    F = Full case
    C = Compressed load

    A = Accuracy load

    LIGHT GREY TEXT BOX INDICATES MAXIMUM LOAD - USE WITH CAUTION!
    LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED

  7. #7
    Quote Originally Posted by swarovski View Post
    Think they are going 2800fps
    No way.

    47.0 grains is giving 2760 fps in my standard length (22") barrel.
    If I'm going to be accused of it then it's just as well I did it.

  8. #8
    My 308 has a 26 inch barrel and I lied, I checked my chrony records and it was 2799fps

  9. #9
    Found some other figures a bit slower Attachment 44357na na na na na
    Last edited by swarovski; 11-07-2014 at 12:28.

  10. #10
    46.5g N140 with 155 Amax gives me 2890 fps out of a 26" barrel. Its a hot load but very accurate.

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