Ramshot Magnum Powder

[matty_1210]

Can I load 303 British with Ramshot Magnum, if so what load?

[ovenpaa]

I would have thought Ramshot Magnum is going to be very slow for the .303 - you could virtually fill the case and not get close to your pressure limits nor get much beyond 2100fps. I can check this with Quickload if you need something to work with.

[meles meles]

Why do Magnum powders burn slowly ?

[phaedra1106]

Why do Magnum powders burn slowly ?

It's the combination of chocolate and ice cream, the required low temperatures impair the ignition thus slowing the burn rate, honest

[matty_1210]

umm a bit of a pain.

I've got a tube of magnum but I'm never going to be loading any thing like 7mm or 338 Lapua and trying to get powder on the Isle of Man is difficult.

[ovenpaa]

This is what QL suggests on the subject:


Cartridge : .303 British
Bullet : .311, 174, Sierra HPBT MatchK 2315
Useable Case Capaci: 49.530 grain H2O = 3.216 cm³
Cartridge O.A.L. L6: 3.075 inch = 78.11 mm
Barrel Length : 25.6 inch = 650.2 mm
Powder : Ramshot Magnum (Big Boy)

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.408% 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

-04.1 96 47.00 2012 1563 24133 5472 69.4 1.752
-03.7 97 47.20 2022 1580 24452 5520 69.7 1.742
-03.3 97 47.40 2033 1597 24776 5569 70.1 1.732
-02.9 97 47.60 2044 1614 25106 5617 70.5 1.722
-02.4 98 47.80 2055 1632 25442 5666 70.9 1.712
-02.0 98 48.00 2066 1649 25783 5714 71.2 1.703
-01.6 99 48.20 2077 1667 26129 5763 71.6 1.693
-01.2 99 48.40 2088 1685 26482 5811 72.0 1.683
-00.8 99 48.60 2100 1703 26841 5860 72.4 1.674
-00.4 100 48.80 2111 1722 27206 5908 72.8 1.664
+00.0 100 49.00 2122 1740 27575 5957 73.1 1.654
+00.4 101 49.20 2134 1759 27955 6005 73.5 1.645
+00.8 101 49.40 2145 1778 28340 6054 73.9 1.635
+01.2 101 49.60 2157 1797 28730 6102 74.3 1.625
+01.6 102 49.80 2168 1817 29129 6151 74.7 1.616
+02.0 102 50.00 2180 1836 29535 6199 75.0 1.606

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 100 49.00 2336 2109 33138 6835 85.4 1.517
Data for burning rate decreased by 10% relative to nominal value:
-Ba 100 49.00 1900 1395 22762 4774 58.6 1.814

[Laurie]

The key points in the above table are the charge burn % value which runs at 69 to 75%, and the PMax psi value (estimated maximum chamber pressure) that runs from 24,000 to 29,500 or so psi, these showing how badly matched this propellant grade is to the application. When you get these sorts of burn rates and low pressures, (.303 wanting to be in the 40,000 - 45,000 psi range and 100% charge burn or close), the inevitable result is inconsistent pressures and velocities due to the propellant failing to reach its 'working pressures' and a very dirty barrel indeed, likely brass and chamber walls too.

Ramshot powders are also double-base ball type, and these usually need loads that take them close to full pressures to burn well. With this level of mismatch, there is even a small possibility of something seriously bad happening - major pressure spike or hangfire.

[matty_1210]

So 47 to 50 grains will work.

I will try to get some thing better for 303. Thanks for the help.