Saturday 26 September 2009

or maybe something a bit bigger? .338-06 A-Square

The fact that any kind of load that achieves decent speeds for the KJG leads to compressed loads in .338 Federal led me to looking for other options. Now I don't want a Magnum for 2 reasons.

1) I don't see any reason. I am not likely to shoot much further than 200m, so why would I need a Magnum?
2) I have found a full length moderator that basically looks like thicker barrel and has a diamter of 25mm, ie looks like a match barrel. This moderator at the moment can use a maximum of 30-06 Ackeley Improved, so I am hoping that the .338-06 will be usable. As that moderator involves drilling holes into the last 1.5" (make that 38mm) of the barrel the usable length goes down to 20.5", ie 520mm. Quickload still recommends Nitrochemie A/S 0300, so that is what I am using here.



**** Input data:                        Date: 26-Sep-2009     Time: 23:03:18
Cartridge................. = .338-06 A-Square
Projectile type........... = 8.58, 9., Möller 8,5 mm KJG S with boattail  

Max.avg.pressure(Piezo A-S)=448 MPa     Shot start / init pressure = 15 MPa
Projectile weight       (g)= 9.01       Groove calibre          (mm)= 8.59
Length of cartridge    (mm)= 84.84      Length of case          (mm)= 63.35 
Case capacity       (cu.cm)= 4.48       Length of projectile    (mm)= 30.48 
Length of barrel       (mm)= 520.7 
**** Values calculated:
Seating depth          (mm)= 8.99       Volume displaced    (cu.cm)= 0.52 
Comb.chamber volume (cu.cm)= 3.96       Projectile travel      (cm)= 46.63 
**** Input data:
Propellant type........... = Nitrochemie A/S 0300
Charge weight...........(g)= 3.592      Load density......(g/cu.cm)= 0.907
Heat of Explosion   (kJ/kg)= 3950       Ratio of spec. heats cp/cv =  1.2401 
Solid density     (g/cu.cm)= 1.62       Weighting factor...........= 0.50
Burning rate factor Ba(1/s)= 0.675      Pro-/degressivity factor a =  0.94 
Burning limit ......... z1 = 0.5        Combust.Chamber Vb     (m³)= 3.962196E-6
Factor.................. b = 1.7        X-S.Area of Bore      A(m²)= 5.695E-5
Bulk density      (g/cu.cm)= 0.944      Projectile mass mp     (kg)= 9.007E-3
Loading ratio           (%)= 96.0       Projectile travel x     (m)= 4.6634E-1
**** Results calculated:
Maximum pressure ........  =  420 MPa     Way of projectile at Pmax=  41.4 mm
Muzzle velocity  ...... Ve =  981m/s      Muzzle pressure .......Pe=  64 MPa
Project. energy at muzzle =  4336J      Fraction of powder burnt  = 100  %
Projectile travel time from 10% Pmax to muzzle = 0.85 ms


KJG needs at least 750 m/s to open properly, so that needs to be achieved at whatever range one intends to hit. As the below ballistics table shows, this lets me do that to slightly beyond 250m:

 Muzzle velocity  : 981 m/s
 Crosswind speed  : 0 m/s
 Ballistic Coefficient(s) (G1):
 C1=0.362@V>800 m/s;
 C2=0.307@V>400 m/s;
 C3=0.335@V>340 m/s;
 C4=0.272@V>300 m/s;
 C5=0.253@V>0 m/s;


 Optimum trajectory information :
 Optimum sight-in range (X) = 190 m
 with max. ordinate above LOS at range (M)= 113 m
 and max. point blank range (P)= 220 m.
-------------------------------------------------------------------------------------
 Sight-in clicks, 1 click = 1.0 cm/100 m or 0.394 in/100 m
 Height of sight above bore axis = 3.6 cm or 1.417 inch
 Gun is zeroed-in at 200 m,
 by sighting-in at level firing
-------------------------------------------------------------------------------------
 Range  Velo Time of  Energy   Path    Deflection    Total  Sight correction  Target
        city  flight            to    at crosswind    drop   for setting new   lead
                                LOS    of 0.5 m/s              zero range     10 m/s
-------------------------------------------------------------------------------------
·Meter   m/s     s    Joule     cm     cm      MOA     cm    Clicks     MOA      m  ·
-------------------------------------------------------------------------------------
|    0   981  0.0000   4336    -3.6    0.0   -----     0.0   ------    -----    0.00
|   25   958  0.0258   4132    -0.6    0.0    0.02     0.3     +2.2    +0.76    0.26
|   50   935  0.0522   3936    +1.8    0.1    0.04     1.3     -3.6    -1.25    0.52
|   75   912  0.0792   3749    +3.5    0.1    0.06     3.0     -4.7    -1.61    0.79
|  100   890  0.1069   3569    +4.5    0.2    0.08     5.4     -4.5    -1.53    1.07
M  118   874  0.1273   3444    +4.7    0.3    0.09     7.6     -3.9    -1.36    1.27
|  125   868  0.1353   3396    +4.6    0.4    0.10     8.6     -3.7    -1.27    1.35
|  150   847  0.1646   3231    +4.0    0.5    0.12    12.7     -2.6    -0.91    1.65
|  175   826  0.1947   3072    +2.4    0.7    0.14    17.6     -1.4    -0.48    1.95
X  200   805  0.2255   2919     0.0    1.0    0.17    23.4      0.0     0.00    2.25
|  225   782  0.2570   2754    -3.3    1.2    0.19    30.1     +1.5    +0.51    2.57
P  229   778  0.2621   2727    -4.0    1.3    0.19    31.2     +1.7    +0.59    2.62
|  250   758  0.2892   2590    -7.6    1.6    0.21    37.7     +3.0    +1.05    2.89
|  275   735  0.3224   2433   -12.9    1.9    0.24    46.4     +4.7    +1.62    3.22
|  300   712  0.3570   2283   -19.5    2.3    0.27    56.3     +6.5    +2.23    3.57
-------------------------------------------------------------------------------------
M = Peak vs. L.O.S, X = Set Zero, P = Max. Point Blank Range
Elevation above Angle of Site (0.0 deg.)  = 0.0772 deg.





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