An Observation on Fouling

[Jim Leinicke 7368V]

As a rule, I shoot relatively light, conventional skirmish loads of faster burning powder (Goex 3fg or Swiss 2fg). I have not really shot much GOEX 2fg simply because I tend to get a lot of fouling in equivalent 2fg loads. However, for deer hunting I load 70 grains GOEX 2fg and the Hodgens skirmish bullet because it is very accurate, flat-shooting, and absolutely devastating on a deer. When I cleaned my rifle after last weekend's hunt (Three rounds fired) I noticed again, as I have noticed before, that there was no appreciable fouling in the barrel. In fact, I believe I could have simply run an oiled patch through the bore and let it go at that.

I am wondering why a 70 grain load of 2fg is so extremely clean burning, while a 43 grain load leaves appreciably more fouling? My guess is that the much higher breech pressure of the hotter loading results in a much more efficient use of the powder. Does anyone have any thoughts on this?

Jim Leinicke
7368V

[P.Altland]

Talked to Frank Garrett once and he said that he used so much powder in his Sharps carbine that barely any smoke left the barrel. More powder + back pressure = more chamber pressure and more efficient combustion. Ever look at someone's barrel who blows off their powder charge at the end of a relay without loading the bullet (which is against the rules)?


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[RaiderANV]

Yes......very against the rules and a penalty.

[John Bly]

Jim, I've been shooting black powder cartridge silhouette for over 20 years now with a 45/70 and a 40/65. Common wisdom among fellow shooters is that to reduce fouling you increase the powder charge. I know it sounds odd but the reasoning is that the higher charge increases pressure which increases the temperature of the burning powder which in turn results in more complete combustion thus less fouling. Another reason could be that the higher pressure results in more ejecta from the muzzle leaving less fouling in the barrel. It could be both. Take your pick.

[jonk]

It's true with smokeless as well. Try loading about 25 gr of 4895 in a 30-06 case vs. 50 and you'll get a lot of unburnt powder. Simply less pressure from a smaller charge to complete combustion. With smokeless it manifests as unburnt powder, with black as more residue.

Oddly, the most accurate load for my musket is using 3f. For my carbines it is 2f, using a lighter load. So just when you think you have a good reasoned approach, out the window it goes...

[Jim Leinicke 7368V]

Now that you mention it, I used to load 28 grains of IMR4198 and some pretty light .45 bullets in an old trapdoor when I was a kid, and there were usually unburned grains left in the breech with those light loads. Anyway, I have heard from all sorts of sources that the best blackpowder load in any breechloader is all the powder you can cram into a case, and I suppose this efficiency of combustion issue is what the old timers were referring to. Anyhow, I think over the winter I may do a bit of experimentation with heavier 2fg loads just to see how I do with them.

Thanks for the responses, folks. And have a Happy Thanksgiving.

Jim Leinicke
7368V

[jonk]

Well now you've opened a can of worms with the whole "best cartridge load is the most bp you can cram into the case."

The use of fillers (COW, kapok, carded wool, etc.) says a lot of guys would disagree. Me being one of them. On a lark I tried 40 gr of 3f in my trapdoor with cornmeal filler. Outshot a compressed case full and no two ways about it. My buddy Ian who shoots BPC silhouette matches has even found that on a calm day, said load will still knock down targets at 550 yards in a silhouette match and he really had the other shooters talking as to what he was shooting. As that's another can of worms, I'd say that all the filler there is having a sealing/scrubbing effect on the fouling, which is another option to consider. The same light load of smokeless that doesn't burn completely often WILL with the use of a filler; which is again, yet ANOTHER can of worms as it is a different ball of wax from bp fillers in terms of doing it safely.

However, the general idea of more powder equals a cleaner burn is very true... the Brits for instance when they switched to the .303 initially used a very heavily compressed load of black, and were getting close to smokeless velocity and cleanliness...

[John Holland]

A great topic & thread going here!

I have a question in the same vein as what is being discussed, but in the opposite direction. What are your thoughts on breech loading black powder cartridges that are using light loads, no filler, and an air gap between the powder and the bullet? Example: A .44-40 with 17 grains of 3F and bullet seated at the neck, which leaves a large air gap. So, when loaded and fired from a horizontal position the powder at best is laying along the bottom of the case from the primer to the bullet. The primer has to be igniting the powder across the top of the spread out powder charge. I know people doing this and have seen some extremely tight groups being produced by this method. All of this takes me back to the Buckskin Report days and their Black Powder Cartridge magazine where the scared me half to death with the word "detonation" of a powder charge if things weren't loaded properly....whatever that is. I never did understand exactly what they were trying to impart to their readers!

Do any of you have any thoughts on this?

JDH

[bobanderson]

I've also shot BPCRS for about 20 years. In my experience, the degree of fouling is more affected by the type of powder and the quality of your bullet lube. I started out shooting "Elephant droppings", then went to Goex cartridge grade, Swiss in 1 1/2 and 3f and finally Goex Express, which is the predecessor of Old Eynsford.

In each instance as I changed powder quality and upped the charge to maximum capacity and even compressed loads, the fouling was always watched closely because in a short timed string of shots, a fouled out barrel can destroy a score.

My take is fill the case to capacity with a fine granulation, quality powder and use a good lube (I'm NOT a fan of SPG) and fouling is at it's least. I've noticed that you can look down the barrel after a shot and if you have good fouling control, the residue is accumulated at the bottom of the barrel and the top half or so is almost clean. In breechloaders, shooting cast bullets sized at least .002 over groove diameter will go a long way in reducing fouling buildup, IF your lube is good.

JDH,
I've shot less than full cases (17 grains of 3f) for years in a 45 Colt at breakable targets at skirmish type events (See Black Powder Through the Ages on Facebook) and have had excellent accuracy. I think the whole detonation thing is more with smokeless shooters using small charges of fast pistol powder, like Bullseye.

[jonk]

Well detonation with any powder is another interesting question. I think that with ANY powder, black included, the culprit is one of two things. Either:
1. If the powder is below the level of the primer and the flame can flash over the top, two sections of the power may be simultaneously ignited, creating a secondary explosion effect when the two flame fronts meet; or
2. The primer is of sufficient force to blow the charge- and bullet- forward, often wedging it an inch or so into the rifling, but only partially igniting the powder column. The bullet at this point acts as an obstruction, and if maximum loads are being used, can raise pressures to an unpleasant extreme.

In the smokeless world, this is usually caused by using too slow of a powder for the case. Actually, very FAST and easy to ignite powders, such as bullseye, are largely position insensitive, and it isn't an issue. They conflagrate fast enough that it isn't a problem. Using a coated slow powder- especially ball or some very slow stick powders- it can be more of an issue. Even then, it's a once in a blue moon thing, something we've heard about but few shooters (luckily) ever see. Naturally, too HIGH a charge of a fast smokleless powder just creates a bomb in front of your face.

Which brings to point the question of reduced loads of black with an air space.

First off: a lot of companies and even militaries had loads using less than a case full of powder. There is certainly a question of load density at work here. A sharps rifle charge for instance creates an air space issue by its very nature, and isn't an issue. My personal thought is as long as load density is 2/3-3/4 at a minimum, no issue will be had. Not that I advocate trying it, it's each shooter's own decision.

My gut feeling is that it is more issue in a muzzle loader due to point 2 above. The primer cap has enough force to blow past some of the charge, ignite a small part of it, expand a bullet skirt or upset a patch into the rifling, creating an obstruction that pressure has to really build behind to get moving. Isaac Newton at his finest; getting an object moving requires a certain force, and KEEPING it moving- and accelerating down the barrel- requires LESS force than to get it moving again from a dead stop, and it is the gentle push created by initial ignition that gets it moving safely. As a shooter cannot reliably estimate load density with a front stuffer short of "fully seated on the powder" not seating it reliably to the powder creates this possibility. Such control IS however possible in a cartridge gun.

That said, There is still the question of point 1 above. Secondary explosion effect. If you get below a certain load density (case being filled a certain percent) there is still the chance of two wave fronts of flame meeting.

So: to sum up I would personally judge a muzzleloader to be shot safely using the ball seated fully only; a breech loader or other cartridge gun to be safe so long as the air space doesn't exceed a certain percent of the case volume (your call on what that may be).

Personally I just use filler or wads to take up said space, as it provides a good secondary characteristic of a gas check effect.