Velocity of 6mm250 load

[ptf18]

List: Would anyone venture an estimate of velocity of a 6mm250 cartridge that uses 32gns of Varget with a MOLIED SMK 107 bullet. This is shot out of my Savage Model 12 with a 30" 1/8 twist barrel.

Thanks,
Lester

 

[techshooter]

Here is what QuickLoad predicts:

Cartridge : 6 mm 22-250
Bullet : .243, 107, SRA HPBT MatchK 1570, Friction Proofed
Cartridge O.A.L. L6: 2.728 inch or 69.29 mm
Barrel Length : 30.0 inch or 762.0 mm
Powder : Hodgdon VARGET

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 71 25.60 2421 1392 30528 5588 97.2 1.781
-18.0 73 26.24 2472 1452 32441 5720 97.8 1.732
-16.0 75 26.88 2523 1512 34457 5844 98.4 1.685
-14.0 76 27.52 2574 1573 36580 5961 98.8 1.640
-12.0 78 28.16 2623 1635 38817 6070 99.2 1.597
-10.0 80 28.80 2673 1697 41173 6172 99.5 1.556
-08.0 82 29.44 2722 1760 43655 6265 99.8 1.516
-06.0 84 30.08 2770 1823 46270 6349 99.9 1.479
-04.0 85 30.72 2818 1886 49025 6424 100.0 1.442
-02.0 87 31.36 2865 1950 51930 6492 100.0 1.407 ! Near Maximum !
+00.0 89 32.00 2912 2014 54992 6558 100.0 1.374 ! Near Maximum !
+02.0 91 32.64 2958 2078 58221 6622 100.0 1.341 ! Near Maximum !
+04.0 92 33.28 3003 2143 61629 6685 100.0 1.310 !DANGEROUS LOAD-DO NOT USE!
+06.0 94 33.92 3048 2207 65227 6747 100.0 1.280 !DANGEROUS LOAD-DO NOT USE!
+08.0 96 34.56 3093 2273 69027 6807 100.0 1.251 !DANGEROUS LOAD-DO NOT USE!
+10.0 98 35.20 3137 2338 73044 6865 100.0 1.223 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 89 32.00 2992 2127 64024 6337 100.0 1.296 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 89 32.00 2790 1849 45994 6738 98.6 1.478

This forum doesn't like the tabular data from QL, but the above data,if you can read it!) shows that the 32 grain load hits about 2912 fps @ 55KPSI.

Note that this load is assuming that the COL is 2.728",0.250 of the bullet in the neck).

This load is also nearly right on the optimum exit time criteria for a 30" barrel, 1.368 mS. If you get about these velocities, you should be right at a good node.

QL usually gets you to within about 2%, but this is not always the case, as powder burn rates vary from lot to lot, and your barrel and bullet combination can make for other variations. I always start about -3% from the QL predictions, and test fire before working up to the final value.

Cheers,

 

[ptf18]

Thank you all.

Lester