For quite some time, the consensus among BPCR shooters was that straight cases were always easier to shoot well than bottlenecked cases in the belief that the bottleneck shape contributed to very stubborn fouling in the throat of the rifle. Mike Venturino suggests that Sharps introduced the .40-70 Sharps Straight precisely in order to get around the fouling issue with the .40-70 SBN.
I have shot a number of bottleneck rounds over the years -- .40-70 Sharps BN, 11 mm Mauser, 11.15 X 58 mm Austrian, .43 Spanish and a couple of others -- and found the problem of throat fouling to be fairly consistent. However, I never really shot more than a few dozens of these rounds out of individual rifles, and never did the serious homework and experimentation that might have led to a solution to the issue. Over the years, I have heard of a few shooters out there getting very good performance out of some of the BN rounds, including one of the oldest in existence, the .44-77.
So I thought I would ask if anyone here is aware of the current "state of the art" regarding the bottlneck rounds and how to make them shoot consistently and cleanly.
I am of course talking about shooting pure black, no substitutes and no duplexing.
All comments most welcome.

Bill, I don’t know what the science would be behind bottlenecks causing more fouling over straight cases other than, perhaps, a straight case offers the expulsion of the burnt solids an easier pathway than a bottle neck.
That said, how much of a hassle is dealing with the fouling?
In competition, bores are wiped between shots.
In a hunting situation, one or maybe two shots are the norm, so not much of an issue there.
The difference in how the Americans developed their black powder cartridges as opposed to the British is quite interesting.
The Americans, utilizing falling block actions exclusively, just kept on lengthening the case to fit more powder.
The British, largely adopting the Martini, had to expand and bottleneck their cartridges to fit in more powder, and so it stuck, the straight 450, 500s and 577s being exceptions.
In competition shooting, bottleneck cartridges were the norm even when true falling blocks (Gibbs, Westleys, Fraser’s etc.) were the preferred rifles.
I suppose one just needs to decide if the fouling is an issue needing to be dealt with.

Yes I have built many BPC rifles with bottle neck cartridges; mostly 38-56, my favorite, and the 40-65 which is not really a bottle neck. Also made a couple of wildcat 40 cals on 45-70 brass.
The only way I found to make them work with zero drama is to load ten percent 5744 under the black powder. That will make them shoot clean as any modern load. Used to use 4579 but they quit making that. Not legal in NRA competition.
But I could win the local buffalo match any time I wanted to.

Thanks fellas.
Huvius, you are right that some of the early long-range target rifles were in bottleneck chamberings. The Remington No. 1 in .44-90 shot by Hepburn, Fulton and Bodine in the Creedmoor Match of 1874 comes to mind. I am not sure how they managed the fouling, but they certainly did -- possibly aided by the quality of powders available at the time. Ned Roberts says the Remington mid-range target rifles were chambered in .40-70 BN, or .44-77 if requested.
Tom, duplexing is a great workaround. Hadn't tried it with 5744.

Duplex is the answer. I've found that I don't have to use the full 10%, 5 seems to work just as well.

"Bill, I don’t know what the science would be behind bottlenecks causing more fouling over straight cases other than, perhaps, a straight case offers the expulsion of the burnt solids an easier pathway than a bottle neck."

Its the smaller area of the barrel what is the problem as the residue can spread more on a large diameter bore.

quote:

Originally posted by Nordic2:
"Bill, I don’t know what the science would be behind bottlenecks causing more fouling over straight cases other than, perhaps, a straight case offers the expulsion of the burnt solids an easier pathway than a bottle neck."

Its the smaller area of the barrel what is the problem as the residue can spread more on a large diameter bore.

What if we are shooting a straight 45/90 as opposed to a 90gr charge in a 450 No.2 Musket?
Same charge, same bullet.
Is the No.2 expected to foul more simply based on the necked cartridge?

Yes.
I do not know the real reason other than the obvious: case shape is different.
I just make it go away.

In poking around on the Net, I read that duplexing with a few grains of FFFFg under a normal charge of FFg was apparently practiced at the end of the buffalo slaughter. Not sure if this had any effect on fouling.

quote:

Originally posted by Huvius:

quote:

Originally posted by Nordic2:
"Bill, I don’t know what the science would be behind bottlenecks causing more fouling over straight cases other than, perhaps, a straight case offers the expulsion of the burnt solids an easier pathway than a bottle neck."

Its the smaller area of the barrel what is the problem as the residue can spread more on a large diameter bore.

What if we are shooting a straight 45/90 as opposed to a 90gr charge in a 450 No.2 Musket?
Same charge, same bullet.
Is the No.2 expected to foul more simply based on the necked cartridge?

I expect it to be a difference in fouling management in the cartridge design, how does the lube groves in the bullet look, how forgiving are the neck and throat area to fouling, are the shooter expected to fire a lot of ammo or only a few during a hunt.