45-70 subsonic loads

[Sigfla]

I have the load data for 410 Subx bullets with tight group. I am prob gonna use those to hunt with. I want some 500gr plinking rounds to mess with and show off the quiet heavy hitter. I have a few bottles of tightgroup (preferred powder) and 2 small bottles of trailboss (would prefer to save rather than plink with). Either way my thought was to start at the 410 grain 13 grains of Tightgroup load from hogden in the 500 grain lead rounds. I figure it may put me at or a little over subsonic and I can go down from there.

 

[dellet]

Depends on the rifle, but probably not the best plan.

The likelihood of that load being over subsonic velocities is out weighed by the likelihood it will be over pressure.

Honestly about half of Hodgdon data for the 45-70 is questionable at best and unsafe for Trapdoor and early rifles. Generally the three pressure levels for 45-70 are 20,000 psi for trapdoor rifles, 30,000 for modern lever actions, 40,000 for strong actions. The 410 grain bullet load is estimated at 28,000 psi. Probably half the rifles on the market, are questionable at that pressure. Note that Hodgdon lists the same pressure limits for trapdoor and lever actions.

Adding 100 grains of bullet weight without reducing charge weight will probably push the pressure near 40,000 psi. Depends on your rifle.

Ruger #1, Winchester Miroku 1885, Marlin lever actions no problem.

All this is complicated by the fact everyone’s go to first sign of pressure is flattened primers. In the case of the 45-70 and other black powder cartridges, trying to read a primer rated for 2-3 times the pressure that the action blows up in your face, is counter productive.

You might look at some other data, but generally heavy bullets with trapdoor rated pressures, will be sub sonic.

 

[nakneker]

I’ve been using a lot of AA5744 is sub loads and mid range loads in quite a few big bore cartridges. It works great in the 45-70 albeit hard to find right now. Below is a link from UR Reloader that or may not help, they use the bullet you mentioned with 5744 and IMR 4895 which should be easy to get. Recently Trail boss hit the market it again but it went fast but if you see 5744 it’s a great option. It’s also not position sensitive in the case which is something I like a lot. I’m using it 45-70, 444 Marlin, 45 Colt, 44 mag and 38-55.

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[Sigfla]

Depends on the rifle, but probably not the best plan.

The likelihood of that load being over subsonic velocities is out weighed by the likelihood it will be over pressure.

Honestly about half of Hodgdon data for the 45-70 is questionable at best and unsafe for Trapdoor and early rifles. Generally the three pressure levels for 45-70 are 20,000 psi for trapdoor rifles, 30,000 for modern lever actions, 40,000 for strong actions. The 410 grain bullet load is estimated at 28,000 psi. Probably half the rifles on the market, are questionable at that pressure. Note that Hodgdon lists the same pressure limits for trapdoor and lever actions.

Adding 100 grains of bullet weight without reducing charge weight will probably push the pressure near 40,000 psi. Depends on your rifle.

Ruger #1, Winchester Miroku 1885, Marlin lever actions no problem.

All this is complicated by the fact everyone’s go to first sign of pressure is flattened primers. In the case of the 45-70 and other black powder cartridges, trying to read a primer rated for 2-3 times the pressure that the action blows up in your face, is counter productive.

You might look at some other data, but generally heavy bullets with trapdoor rated pressures, will be sub sonic.

It’s a TC encore with a 16” custom fast twist MGM heavy barrel.

 

[XTR]

Somewhere around 10g or 11g of Unique has been used under 405s in a 45-70 for a very long time. A pound goes a long way

 

[dellet]

I would stay away from the Ruger/strong action loads, too many other good loads available, without risking long term damage to the contender.

The titegroup load is not something I would do without running some models because it barely make velocity with a 410 grain bullet, and will only get slower with a higher pressure with the 500 grain bullet. Then since you have a 16” barrel, you’ll need to add more powder to make up for the velocity drop, unless you want to shoot at 900 fps.

Basically any load you find around 1300 fps in a 24” barrel, normal for published data, is a potential sub load. That opens up a lot of combinations. Just be mindful of ultra fast powders and trying to reach published velocities.