Thursday 17 September 2009

.338 Federal

The .338 Federal is a nice "against the trend" development by Federal. All tests seem to agree that it is quite a deadly little cartridge, which is basically a necked up .308 Winchester. I had a few doubts about usability with KJG, which demands rather high speeds, but it looks good:

**** Input data:                         Date: 17-Sep-2009     Time: 01:21:09
Cartridge................. = .338 Federal
Projectile type........... = 8.58, 9., Möller 8,5 mm KJG S with boattail
 
Max.avg.pressure(Piezo Wil)= 415 MPa     Shot start / init pressure = 15 MPa
Projectile weight       (g)= 9.01        Groove caliber         (mm)= 8.59
Length of cartridge    (mm)= 71.12       Length of case         (mm)= 51.16 
Case capacity       (cu.cm)= 3.73        Length of projectile   (mm)= 30.48 
Length of barrel       (mm)= 560 
**** Values calculated:
Seating depth          (mm)= 10.52       Volume displaced    (cu.cm)= 0.61 
Comb.chamber volume (cu.cm)= 3.13        Projectile travel      (cm)= 51.94 
**** Input data:
Propellant type........... = Nitrochemie A/S 0300
Charge weight...........(g)= 3.04        Load density......(g/cu.cm)= 0.972
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)= 3.126347E-6
Factor.................. b = 1.7         X-S.Area of Bore A(m²)= 5.695021E-5
Bulk density      (g/cu.cm)= 0.944       Projectile mass mp(kg)= 9.007E-3
Loading ratio           (%)= 103.0       Projectile travel x(m)= 5.1936E-1
 
**** Results calculated:
Maximum pressure ........ =  400 MPa     Way of projectile at Pmax =  32.7 mm
Muzzle velocity  ......Ve =  949 m/s     Muzzle pressure .......Pe =  48 MPa
Project. energy at muzzle =  4053 J      Fraction of powder burnt  = 99.8  %
Projectile travel time from 10% Pmax to muzzle = 0.92 ms


This looks like a nice starting load for this cartridge and it only slows down to < 750 m/s beyond 225 m which strikes me as OK. The BC of the short 8.5mm KJG are not overwhelming but still the ballistics look sufficient. Wants!



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