.303 reload data

[gunnut69]

Does anyone have a recipe to match the mk7z, I want to use IMR4895 with a 174gr FMJBT?

Thanks

[Parashooter]

IMR data, piezo pressure -

303 BRITISH
WIN. CASE; REM. 9 1/2
SIERRA 180 GR. SPITZER
.311" DIA.; 24" BBL.; 3.035" C.O.L.
Powder Charge Vel. p.s.i.
IMR 4895 41.0 2399 46100

QuickLOAD estimates -

Cartridge : .303 British
Bullet : .311, 174, Sierra HPBT MatchK 2315
Cartridge O.A.L. L6: 3.075 inch or 78.11 mm
Barrel Length : 25.0 inch or 635.0 mm
Powder : IMR 4895

Predicted data by increasing and decreasing the given charge,
incremented in steps of 3.0% 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
-06.0 87 38.54 2403 2231 37179 6442 97.2 1.422
-03.0 90 39.77 2473 2363 40447 6624 98.1 1.369
+00.0 93 41.00 2543 2498 44002 6787 98.8 1.318
+03.0 96 42.23 2612 2635 47876 6929 99.4 1.269 ! Near Maximum !
+06.0 98 43.46 2680 2775 52102 7049 99.8 1.223 ! Near Maximum !

[Art]

174 gr. boat tail bullets actually mimic the ballistics of the 174 gr Mk VII pretty closely when it comes to ballistic coefficient because the first 1/3 of the Mk VII bullet under the jacket is aluminum making it very long for a flat base spitzer bullet weighing 174 gr. My manual (Hornaday) doesn't list IMR 4895 in its powders for .303 British but I believe the U.S. government manufactured MK VIIz for the Brits in WW II using IMR 4895. If so it is a propellant that was actually used in military Mk VII ammunition. Both factors lighten your load in your quest.

Bottom line - any load that gets you velocities between 2425 fps and 2475 fps should work ok. According to parashooter's data that probably means somewhere between 39 and 40 gr of IMR 4895 which sounds about right to me.....

[Sunray]

Mk VII ammo used a 175 grain BT at 2440 fps. The data below was tested by Steve at .303british.com with a 174 grain Matchking. OAL - 3.075 inches.
Start: 38.0 grains (2196 fps) Max: 42.0 grains (2468 fps)

[Parashooter]

Mk VII ammo used a 175 grain BT at 2440 fps. . .

No, the Mk.VII bullet features a flat base. The boattail version was the Mk.VIII (Mark 8).

[Art]

No, the Mk.VII bullet features a flat base. The boattail version was the Mk.VIII (Mark 8).

Yup, and the only difference between Mk VII and Mk VIIz is the propellant. MkVII uses cordite and Mk VIIz uses nitro cellulose ball, flake or stick powders which is what the OP indicates will be used in his loads. Cordite is a bit hard to get these days.