Q about a shooting session with BP and smokeless

[Big Mak]

Typically I shoot one, or the other, in my 45/70 Trapdoor but never in 7 years have I used them both in same session. (AA5744 and a 405 gr bullet OR real BP, either 65 gr or 68 compressed, depending on the bullet)

Any reason not to follow up a BP session with some smokeless in the same rifle, after cooling the barrel and running a few patches down the barrel of course.
We're talking about a new Sharps 45/70 rifle.

[Lead pot]

Mak,

Please don't take this wrong for what I'm about to say. It's your rifle so do what you like.
I have seen three rifles fragment using 5744, a Ballard I stood close by when it went. I seen the remnants of a 74 sharps and a 85 high wall, both reproductions not originals. I have shot 3031 in my 74 sharps a few times but it jus made me uneasy. A light load can be just as dangerous as a heavy over load in these large capacity cases.
But to answer your question if you can change loads after cleaning I see no reason why not. But I would not use a jacketed and shoot a GG lead with out totally cleaning the copper out before doing it or shoot black then smokeless jacketed bullet. The copper fouling will trap the black powder fouling under it and make a mess when the trapped fouling ruined the bore.
I made a mess out a fine roller when I was a kid back in the 50's doing this.

[Big Mak]

Thanks for the feedback LP. Did you know that Powder River cowboy 45/70 loads are 26 gr of AA5744? (405 bullet) The owner gave me their recipe. They made them from 2007 until closing the doors, around 2017.
I had used them for 2 years in my trapdoor with no ill effects before I started rolling my own. They measure 1200 fps. Very mild.
Very sorry for your experiences! I primarily use BP 80% of the time now.

Also, I've never used copper 45/70 bullets. If I cast em, then I blast them, except before I reloaded and bought low pressure loads from Powder River.

[country gent]

I would recommend a decent cleaning between the 2. Powders dont always get along causing poor accuracy, another issue might be the possible baking cooking or hardening of BP fouling with the smokeless.I personally dont care for the light smokeless loads. Just to much airspace for me. A good dose of properly compressed black Powder wads and bullet seem to do best for me with single digit SDs and very low ESs.

[rfd]

if the gun is of modern steel, and rated for smokeless cartridges, proper aa5744 loads should not be of concern in that particular gun. i shot a LOT of aa5744 under greasers in rollers and sharps before i got the holy black religion and have never once looked back at that white devil dust aa5744 should NEVER be accompanied by wads or fillers as therein could lie a bomb in the making (as noted via the quigley match rules concerning double base powders). this powder is meant for the cartridges of yesteryear and are claimed to not be position sensitive. using it after or before firing black powder cartridges might, and probably will, only account for consistent accuracy issues unless rifling cleaning is accomplished prior to shooting.

from accurate arms ...

"It (5744) can best be described as a fast burning Rifle or slow burning Magnum handgun double base “hybrid” powder, having the typical chemical composition of handgun powders i.e. 20% NG – and the geometry of a typical extruded single perforated rifle powder.

Rifle applications:

This makes the powder very ignitable, which makes it ideal for low loading density applications, such as reduced loads on bottle neck rifle calibers, and low performance “straight case” designs, such as the old “black powder” calibers i.e. 45-70 45-110 50-110 etc.

The powder is virtually insensitive to powder position, and there is no need for “fillers”. It will deliver consistent results at low performance levels. Although there will be some un-burnt powder (see paragraph below) the performance will remain consistent.

Due to its ignitability, any strength rifle primer can be used.

Handgun applications:

This powder makes for an excellent powder in large capacity handgun calibers such as 44/45 “Magnum” types or “std” cases with similar capacities. With some of these calibers full power or close to full power is achievable, usually at full case/maximum loading densities. The powder can also be at reduced levels in handgun calibers, but with same effect re un-burnt powder. (See paragraph below)

Un-burnt powder granules:

Although, this is a powder recommended for reduced/low performance loads, it cannot be completely efficient (clean burning) at very low Pressure/performance levels of <18000psi.

It still is a modern, high-density, smokeless powder, with limitations regarding complete combustion at very low chamber pressures. With nitro-cellulose based “Modern” powders, the burn rate and pressure are directly proportional.

This means that some level of un-burnt powder will be present, constituting the remainder of some of the powder granules. This cannot be improved with primers or crimp etc, the only way to eliminate this, is an increase in chamber-pressure."

[sharpsguy]

Mak--Listen to Lead Pot. He knows what he is talking about. In my experience, going back and forth between black and smokeless will keep your barrel from settling in. Also, and I have gotten careless about this, shooting grease groove bullets in a barrel that has a history of shooting paper patched ammo will cause accuracy to suffer. I will add that none of my Sharps or my roller has ever seen a jacketed bullet

[Big Mak]

Roger wilco, thanks for the feedback guys!