Safe load for Trap-door Springfield Rifle?

[Rapidrob]

I need a safe load using IMR 3031 pushing a 460 grain round nose flat based LEE cast soft bullet.
After much research I found that 37 grains with no Dacron wad and magnum primer should be no more than 14,000 PSI and 1,200 fps.
I do not have another powder on hand that would work.
Have any of you used this load?

[NSB]

In sixty years of loading the only powder I’ve ever, repeat EVER, had that failed to ignite and caused a bullet to lodge in the bore was 3031 in a 45-70. For the record, I hand dip each load and trickle up to the correct charge in my 45-70 rifles. My point is, if you’re using 3031 in light charges use the Dacron fill. Not a Dacron “wad”, a Dacron filler. The charge of 3031 in my gun looked like a lump of brown goo that got hard. It melted, it didn’t ignite.

[Larry Gibson]

I have used a commercial cast (unknown make or mould) 460 gr bullet over 36 gr od 3031 with a dacron filler for right at 1200 fps out of my H&R Officer's Model 45-70. I did not pressure test it but it was relatively mild. Accuracy was very good with the dacron filler.

[Rapidrob]

I took 60 rounds to the range for a 200 meter test on AR550 armor man torso target
My rifles front sight blade was changed to a modified taller blade and the rifle shot very low at 200 meters. After finding the zero, The rifle shot accurately with no issues.
I did use IMR-3031 @ 37 grains and a Dacron "tuff" and the RCBS 460 grain RNFB bullet sized to .458 and,ready for this.... Lee Factory crimp die just to keep the bullet from being blown forward by the primer, a Winchester Magnum LR .
I did notice as the barrel heated up rounds missed the target to the right. The Windage adjustment worked though not very precise as one would expect ( not a Buff sight )
I used Red Rooster bullet lube and did get some leading. I may have to try another brand to see if the leading is reduced.
One other club member used my loads as well and shot very well with the Buffington rear sight and original front sight blade on his rifle. His first shot was three feet high at 200 meters. Once the sight was lowered to the lowest point and he held at six o'clock the rounds were on target. After the shoot the missed shots were easy to find as they left a large crater with a ditch. All bullets found mushroomed very well.
When struck the 100 pound target jumped and spun on its chain. Impact is impressive.
I've been shooting the .45-70 rifles since '72 and the trapdoor for the last 30 years. I'm a fan of the Marlin 1895 rifle and that was my go-to big bore hunting rifle.
This is the first time I used a safe smokeless powder load in the trap door rifle and it did much better than I'd thought it would. I know there are better powders but your not going to find them on the shelf or at a price that is not greed driven.
Here's the target after 50 odd hits. 20 of the rounds were powder coated and measured .460 and shot to the same place as the plain Jane bullets.
Lee make a mold for 405 grain hollow based .459 ( Mine' ball type) bullet that looks interesting. I may buy it and try those for some fun.
Here is the 200 meter target after 50 some odd hits. The support pole caught one. Five of the missed shots recovered from sand. The red Rooster lube is some tough stuff.