Anyone have a conversion factor for Cordite to IMR 3031 ? kinda new to the game and haven't seen one.

I wouldn't use 3031 as it can become critical in too narrow a window. Either Alliant Reloder 15 or 4831, IMR or H. Hornady factory is loaded with H4831.

Start load with 400 grain would be about 64 grains RL 15, plus 2 grains Dacron fill or Kynoch foam wad. Start load with IMR 4831 would be about 76 grains, no filler required. Work up to standard velocity adjusted for barrel length, shooting over a chronograph.
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"Serious rifles have two barrels, everything else just burns gunpowder."

Thank you for your quick response 400 Nitro Express, I'll avoid IMR 3031

I just loaded 20 rounds of it for my big hog hunt this weekend; 70 grains of 4350 groups best in my K gun. good luck. I also load 76/4831 but it kicks a bit more for the same results. Like was mentioned, they don't use 3031 any more, although years ago, that was the thing to do. However, if you have a Ruger, you can do things that you wouldn't want to do in a DR.

RW are you using a vintage double or a newer rifle?

In my vintage dou ble RL-15 gives me very consistant velocities. I've been using RL-15 for over 13 years now in my double.

Mark,
can you please explain ? and would this apply to this caliber only ? I am curious because I have been given a load using 3031,from a very trusted source for my 470,I am also wondering ,given the differences in different lots of powder with Rx 15,why still it is as popular as it is,thanks.

quote:

Originally posted by 400 Nitro Express:
I wouldn't use 3031 as it can become critical in too narrow a window. Either Alliant Reloder 15 or 4831, IMR or H. Hornady factory is loaded with H4831.

Start load with 400 grain would be about 64 grains RL 15, plus 2 grains Dacron fill or Kynoch foam wad. Start load with IMR 4831 would be about 76 grains, no filler required. Work up to standard velocity adjusted for barrel length, shooting over a chronograph.
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"Serious rifles have two barrels, everything else just burns gunpowder."

To answer a few questions raised on the forum. I have a C Boswell 450/400. It shoots well with RL-15. However, I too have a reloading formula for my 470NE given to me from a trusted source in Enid Oklahoma using IMR 3031. Since I have a fair amount of IMR, I just wondered if there was a conversion factor to help work up a load with the IMR in my 450/400. The Rl-15 seems to work better in my 470 also so I might just avoid the IMR 3031 all together.

RW I will be glad to email you the "Reloading the Nitro Express" article by Ross Seyfried. Just send me our email addy. rkmojo@aol.com

I know the "source" well, and damned few are as competent. On this question, there are certainly different schools of thought though.

Back in the early days of reloading the large flanged nitros - after the source of factory ammunition closed down and handloading became necessary - the most common approach was to use a modern powder that produced the same ballistics with a charge of the same or similar weight as the original charge of Cordite - usually IMR 3031. As Graeme Wright writes in the current edition of "Shooting the British Double Rifle", reports circulated about unpredictable pressure excursions with it, resulting in "rifles being jammed shut, stretched actions, actions coming loose after only a few rounds and rifles blowing up". Ross Seyfried wrote that he felt 3031 could produce pressure spikes (become "critical") with only with slight increases in charge when working up in the large cases. Graeme Wright seems to agree that it isn't suitable for these cartridges, saying "This is not to say that there is anything wrong with IMR 3031. It is just to say that it is not suitable in large cases". The next step was RL 15 and 4831.

So yes, IMR 3031 was the most common powder used in these cartridges in the early days of reloading them, and is now out of favor. Despite having chronographs and access to at least some pressure tested data today, it still isn't difficult to get it seriously wrong in a double rifle if you don't know what you're doing. Given that chronographs were anything but common in those days, and pressure tested data for these cartridges with any propellant other than Cordite nonexistant, is it possible that the problems reported with 3031 back then were simply the product of necessarily flying blind? I think it probable. Still, 3031 is faster burning, so there's less room for error, and I want all I can get.

Who knows who is right? The man has damn few peers and his opinion is nothing if not well informed. He's certainly entitled to a slight difference of opinion.
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"Serious rifles have two barrels, everything else just burns gunpowder."

400 Nitro Express, thankyou for our words of wisdom and experience. I am a novice and certianly want as much room for error as possible. I just hads some extra powder and was curious about using it in another rifle. But no more than it costs I think I'll use RL15 since it seems to work well in both double rifles I have. Thanks RW Taylor