Need a little load data help

[Gnome75]

I have been reloading 303 British with 150 gr interlock and IMR 3031. I want to start using 123 or 125 (.310) projectiles with the IMR 3031 because they are cheaper. I don't have load data for the combo I want to use.

So the question is what is a safe range for how much IMR 3031 I should be putting in?

Is there such thing as too low amount of powder?

I don't hunt do I don't care about getting top performance. I am just taking it out plinking

 

[bugs]

.303 start with 38gr 42 is listed as max load good luck

 

[Gnome75]

.303 start with 38gr 42 is listed as max load good luck

Ok, thanks.

 

[Chilly807]

As to your "too low an amount of powder" question, I think the answer is yes.
I've read a bit about "secondary explosion" or detonation, which as I understand it occurs when the primer flashes over the surface of the powder charge rather than burning evenly from the case head end of the cartridge.
Essentially it burns from both ends, causing much more of the powder to ignite immediately than would normally occur. This can, apparently, result in extreme high pressure spikes.
I'm relatively new to reloading, but this was something I've read in a couple different places.
The Hornady manual makes mention of it indirectly, warning against using very low charge weights in some calibres due to possible high pressure. .243 Winchester page has that warning for sure.

 

[nitro-express]

I have been reloading 303 British with 150 gr interlock and IMR 3031. I want to start using 123 or 125 (.310) projectiles with the IMR 3031 because they are cheaper. I don't have load data for the combo I want to use.

So the question is what is a safe range for how much IMR 3031 I should be putting in?

Is there such thing as too low amount of powder?

I don't hunt do I don't care about getting top performance. I am just taking it out plinking

I'll add a comment; I have used the 150 interlock, and 3031, but when I changed to Varget and Speer Hotcor 150's my groups were cut in half. I've gone through 200 bullets in the last couple of months, they are a winner in my book. General consensus is that the 303 Br prefers a heavy bullet, the military bullet was 174 gr. I have used 3031, and military loads are loaded with 3031 or a very similar powder. 3031 is pretty stable and it's claim to fame is that it mimics cordite, so the sights on the several million SMLE's in service didn't have to have there sights adjusted.

Starting with the fifth, the Hornady manual has data on using the 7.62x39 bullet, and they list 3031, same numbers as below, 37.2 > 42.9, 2500 > 2900. I looked up data on the Hodgdons site, and 3031 was not on the list. As you can see from the data, there may be better choices for powder. You may want to be as close to 3000 fps as you can get. At that velocity that bullet should get things done. Milk jugs full of water, pop or cheap beer cans get RTS pretty quickly. Just my guess, I haven't used that bullet yet, but given the scarcity of 303 bullets, I may try some SST's. I have 2 fantastic 303 Br shooters, and they aren't selling, so I may have to keep them and have the fun myself. I am also considering using cast, the LEE DC C312-185-1R looks interesting. And my starting powder for those would be 3031. Keep us posted.