IMR 3031 load data (replicating 303 Mk. VIIz)

Although I’ve had a bit of a look round this forum, I’ve never actually posted here before. I’ve only just made an account today as a matter of fact.

I will be acquiring a 1921 Lithgow SMLE Mk. III* quite soon, and I’ve been looking into reloading as a bit of a side hobby (and to save a little bit of money. 20 rounds of PPU 303 is about $35 here). I want to replicate the military load as closely as possible.

From a little bit of research, it seems (correct me if I’m wrong) that 303 Mk. VIIz was a wartime expediency loaded with DuPont No. 16 powder instead of cordite (which was used in Mk. VII). I then discovered that IMR 3031 is basically a development of the No. 16 powder. As a result, I assumed that IMR 3031 would be perfect for replicating the velocity and pressures of Mk. VIIz ammo, being almost the same as the powder that was actually used.

The trouble is, I haven’t been able to find any load data for IMR 3031 with a 174 grain projectile. I also have had trouble finding any historical information regarding the original No. 16 load in Mk. VIIz to use as a guide (well, there is a weight of around 40-41 grains mentioned on Wikipedia, but I had hoped to find some information from a more reputable source).

My question is, simply, can anyone help me? My main aim, as I mentioned earlier, is simply to replicate the performance of Mk. VIIz, namely a muzzle velocity of around 2400fps. I would greatly appreciate any advice.

Thanks,

William

britrifles, thanks for the information regarding powders. I have read before that AR2208 is a good powder for reloading 303, and now that you've mentioned it I may consider using that instead. Just a quick question for you: what exactly are the benefits of having lower pressure? Is it to do with protecting the rifle, or something else? Also, thanks for the heads-up on the Sierra bullets. Sounds like I'll give them a try when the time comes.

SW28fan, I'm afraid that the link isn't working for me. Something about my IP address being banned(?). I'll try it again on another device and see if it works.

Shamu, thanks for letting me know! Although I may end up using AR2208, I think I'll still have a bit of an experiment with 3031, so the data you've given me will be quite helpful.

Thanks again,

William

Because I’m up for a bit of experimentation, I probably will get some 3031 soon, and I’ll certainly follow your advice!

I suppose I may need to buy a chronograph if I want to know the muzzle velocity, though. Is there a way to work up a load without using one?

Thanks,

William

Thanks for the information again.

As to my purpose, I certainly don’t plan on competition shooting or anything like that. I’ll mainly just be shooting for fun, and possibly to eradicate the occasional pest (I live on a farm, so there’s usually something to shoot). I suppose I just want a load that’s ‘close enough’ to Mk. VII, mostly for historical interest. That’s the reason I’m buying the rifle after all.

Because of that, I think that AR2208 will be perfect for what I want to do, especially if it’s better for the barrel’s longevity. It turns out that there was an almost full tin in my dad’s garage, so I’ve accidentally acquired some now anyway. It was manufactured in 1987(!), but I suppose it’s still alright. It certainly looks fine.