Real Black vs Pyrodex velocities

[Nuthatch]

According to my BP loading manual, Pyrodex gives a slightly higher velocity than real black. Last weekend, I was sighting in checking my zero on my Hawken for hunting season. This rifle was dead on at about 2" high at 50 last year. And by dead-on, I mean that I could hit a 1" circle at 50 yards with a good rest. With roundball, I have to have the sight at its lowest setting for this zero. It's a cheap plastic sight from Traditions. Because I use it on backpacking trips, I had even superglued the sight in place at the lowest notch so it wouldn't move on me out in the backcountry.

I wanted to use my homemade powder and caps this year. So I took some shots with a 70-grain equivalent load of homemade black (original loading was 70 grains Pyrodex) and was consistently hitting about 6" high at 25 yards. The group was great -- not much more than an inch or two. But consistently 6" high. For kicks, I took aim at an empty gas can sitting at 100 yards, figuring that 6" high at 25 should put me roughtly dead on at 100. Through the smoke, I saw that gas can tumble back off the stump -- a near perfect hit in the center of the can.

Unfortunately, I didn't chronograph any shots to see if my velocity was any higher. But, based on the point of impact, it appears that I'm getting WAY more speed out of this loading. So what gives? Can 70 grains of real black actually give higher speeds than 70 grains of Pyrodex? Can hotter caps give that much more speed? Can a different powder shift the point of impact up without actually increasing the velocity? The patch/ball combo is the same. The sights are the same. The only change is the powder & caps. Scratching my head on this one.

 

[azmntman]

Home made vs factory Goex or equivalent is yer answer. Not a pyrodex fan but used it for years when black was unavailable locally. Never had any performance issues from Pyrodex even with REALLY old can. Stick with what works. Note your next batch or home made may perform differently too. No way to have the same standards for consistency the big factory products have, so just check and adjust zero with each patch.

 

[Ozark Mtn Muzzleloader]

Your home made powder is probably (almost certainly) producing lower velocities than pyrodex causing the higher impacts. The lower speed causes the ball to be in the barrel longer thus exiting the muzzle when the barrel is higher in recoil. This phenomenon is easily observed in fixed sight handguns. Lighter bullets (faster) impact lower while heavier (slower) bullets hit higher. Obviously once further range (drop) enters the picture it becomes less cut & dry or as obvious. I’m fascinated with the concept of making the powder & caps. How are you doing it?

 

[brownac1983]

Are you press corning your powder? Have you checked it by weight against the scale on your powder measure?

 

[SDSmlf]

According to my BP loading manual, Pyrodex gives a slightly higher velocity than real black. Last weekend, I was sighting in checking my zero on my Hawken for hunting season. This rifle was dead on at about 2" high at 50 last year. And by dead-on, I mean that I could hit a 1" circle at 50 yards with a good rest. With roundball, I have to have the sight at its lowest setting for this zero. It's a cheap plastic sight from Traditions. Because I use it on backpacking trips, I had even superglued the sight in place at the lowest notch so it wouldn't move on me out in the backcountry.

I wanted to use my homemade powder and caps this year. So I took some shots with a 70-grain equivalent load of homemade black (original loading was 70 grains Pyrodex) and was consistently hitting about 6" high at 25 yards. The group was great -- not much more than an inch or two. But consistently 6" high. For kicks, I took aim at an empty gas can sitting at 100 yards, figuring that 6" high at 25 should put me roughtly dead on at 100. Through the smoke, I saw that gas can tumble back off the stump -- a near perfect hit in the center of the can.

Unfortunately, I didn't chronograph any shots to see if my velocity was any higher. But, based on the point of impact, it appears that I'm getting WAY more speed out of this loading. So what gives? Can 70 grains of real black actually give higher speeds than 70 grains of Pyrodex? Can hotter caps give that much more speed? Can a different powder shift the point of impact up without actually increasing the velocity? The patch/ball combo is the same. The sights are the same. The only change is the powder & caps. Scratching my head on this one.

I don’t think you mentioned it, but did you try your Pyrodex load at the same time (you know a ‘control’ group) to be sure nothing changed with the gun? And are you confident your Pyrodex hasn’t degraded over time? This past July 4th brought out an unopened pound of the stuff from 1989 (according to the label) and loaded it up in a short blunderbuss with a cotton ball on top of the charge for the ‘young at heart’ to make noise. Got nothing more than a ‘pisssst’ and a puff of smoke. Loaded up the same charge (by volume) of Goex and rattled the windows.

Another thought, I see from your profile you are in California. Any chance you are using non-lead roundballs? Maybe a different lot since last time out?

Whatever is going on, without a chronograph to confirm velocities, you will likely just be guessing.

 

[Nuthatch]

Home made vs factory Goex or equivalent is yer answer. Not a pyrodex fan but used it for years when black was unavailable locally. Never had any performance issues from Pyrodex even with REALLY old can. Stick with what works. Note your next batch or home made may perform differently too. No way to have the same standards for consistency the big factory products have, so just check and adjust zero with each patch.

Pyrodex works but only kinda sorta. 1st shot rarely has any hang ups. But 2nd & 3rd shots almost always ignite slow. Real black feels more like centerfire to me. So I'm switching.

 

[Nuthatch]

Your home made powder is probably (almost certainly) producing lower velocities than pyrodex causing the higher impacts. The lower speed causes the ball to be in the barrel longer thus exiting the muzzle when the barrel is higher in recoil. This phenomenon is easily observed in fixed sight handguns. Lighter bullets (faster) impact lower while heavier (slower) bullets hit higher. Obviously once further range (drop) enters the picture it becomes less cut & dry or as obvious. I’m fascinated with the concept of making the powder & caps. How are you doing it?

That makes some sense. Thanks for that insight. Sounds like I need to also check to see if I see the same POI off hand or on a softer rest if it's a recoil thing. I notice changes like that from airguns where velocities are low. Maybe that's what I'm seeing.
Sorry -- forum rules prohibit talking about how to make powder & primers.

 

[Nuthatch]

Are you press corning your powder? Have you checked it by weight against the scale on your powder measure?

I won't talk about how I make the powder (forum rules). Only that I was using a 70 grain equivalent load. In my case, it's 100 grains by volume, which is 70 grains by weight. My can of Schutzen 3F weighs almost exactly the same weight as by volume (70 grains by volume = 70 grains on the scale). I had done some testing of my powder on a different gun and found that all I needed to do was up the powder charge by 40% to get the same POI vs Pyrodex. Never chrono'd the stuff though. Granted, all those tests were done in the winter where, here, humidity is very high. It's dry as a bone now.

 

[Nuthatch]

I don’t think you mentioned it, but did you try your Pyrodex load at the same time (you know a ‘control’ group) to be sure nothing changed with the gun? And are you confident your Pyrodex hasn’t degraded over time? This past July 4th brought out an unopened pound of the stuff from 1989 (according to the label) and loaded it up in a short blunderbuss with a cotton ball on top of the charge for the ‘young at heart’ to make noise. Got nothing more than a ‘pisssst’ and a puff of smoke. Loaded up the same charge (by volume) of Goex and rattled the windows.

Another thought, I see from your profile you are in California. Any chance you are using non-lead roundballs? Maybe a different lot since last time out?

Whatever is going on, without a chronograph to confirm velocities, you will likely just be guessing.

A control load -- that would have been smarter. Now I'm starting to think I shouldn't take that rifle out hunting just yet...

I tried a couple bismuth balls but most of the shots were the same ol' Hornady swaged lead balls I've been using. They impact the same anyway.

 

[brownac1983]

In my case, it's 100 grains by volume, which is 70 grains by weight. My can of Schutzen 3F weighs almost exactly the same weight as by volume (70 grains by volume = 70 grains on the scale).

I think that might be your answer, or at least part of it. Your powder is less dense, which means it has more surface area for a given weight. More surface area means it'll burn faster than the same charge of the same granulation of black powder at standard density. In essence, your 3F might behave more like 4F.

 

[Nuthatch]

I think that might be your answer, or at least part of it. Your powder is less dense, which means it has more surface area for a given weight. More surface area means it'll burn faster than the same charge of the same granulation of black powder at standard density. In essence, your 3F might behave more like 4F.

That bears some thought for sure. A quick google search found this old document: THE INFLUENCE OF PHYSICAL PROPERTIES ON BLACK POWDER COMBUSTION, which had this to say on page 39 of the pdf.

"however, it is clear that flame spread rate decreases as density increases."

My first thought is that I need to stay with very moderate powder charges if the burn rate is more along the lines of 4f powder -- pressure spikes could become dangerous. My second thought is that, yes, it is possible that low density powder could be giving me higher velocities. The POI is about what I would expect from 90+ grains of 2F Pyrodex. But that 2F Pyrodex would burn slower and have less pressure than a faster burning powder.

I think I'm going to have to do some more shooting & pull out the chronograph to know for sure what is happening on my velocities.

Thanks for that thought.

 

[brownac1983]

Ye

That bears some thought for sure. A quick google search found this old document: THE INFLUENCE OF PHYSICAL PROPERTIES ON BLACK POWDER COMBUSTION, which had this to say on page 39 of the pdf.

"however, it is clear that flame spread rate decreases as density increases."

My first thought is that I need to stay with very moderate powder charges if the burn rate is more along the lines of 4f powder -- pressure spikes could become dangerous. My second thought is that, yes, it is possible that low density powder could be giving me higher velocities. The POI is about what I would expect from 90+ grains of 2F Pyrodex. But that 2F Pyrodex would burn slower and have less pressure than a faster burning powder.

Thanks for that thought.

Yeah, I'd definitely be cautious abut the burn rate. You may have good results if you adjust your granulation to compensate. For example, if your 3F burns like 4F, then your 2F might burn like 3F. I'm 100% sure there's more to it than simply granule size, but that might get you in the ballpark of 3F equivalent.

 

[Archer 756]

BS who really cares, just shoot. I don't think that anyone is that perfect at shooting all I know that my load of BP, kills deer

 

[Nuthatch]

Ye

Yeah, I'd definitely be cautious abut the burn rate. You may have good results if you adjust your granulation to compensate. For example, if your 3F burns like 4F, then your 2F might burn like 3F. I'm 100% sure there's more to it than simply granule size, but that might get you in the ballpark of 3F equivalent.

Looking more closely at the grain size, I’m guessing my homemade screens out a combo of 2-4F. The shapes are irregular. So if I’m averaging around 3F in size but in a lower density, then my burn rate might more closely approximate 3-4F, resulting in higher pressure and velocity. My reloading manual suggests that just going from 2F to 3F gives 100+fps. And I know from previous testing that my POI is what I typically see with a 90-100 grain charge of Pyrodex RS. So, yes, it’s possible that my speeds are faster (albeit with possible pressure issues).

 

[Nuthatch]

BS who really cares, just shoot. I don't think that anyone is that perfect at shooting all I know that my load of BP, kills deer

Glad you know. I don't yet know.

 

[brownac1983]

Looking more closely at the grain size, I’m guessing my homemade screens out a combo of 2-4F. The shapes are irregular. So if I’m averaging around 3F in size but in a lower density, then my burn rate might more closely approximate 3-4F, resulting in higher pressure and velocity. My reloading manual suggests that just going from 2F to 3F gives 100+fps. And I know from previous testing that my POI is what I typically see with a 90-100 grain charge of Pyrodex RS. So, yes, it’s possible that my speeds are faster (albeit with possible pressure issues).

Yeah, I think that's likely. your bigger surface area due to density and irregular grain shape is giving you a faster burn rate, which would result in reaching peak pressure earlier in the combustion cycle. There should be an ideal grain size where your powder would have approximately the same burn rate as commercial 3F, but it'll take some experimentation to find it. A proper chronograph would be really helpful if you go down that road.

As far as pressure goes, there's not really a great way to know the pressure curve unless you actually instrument a test barrel, but one experiment you could do, if you have access to various guns of the same caliber and different barrel lengths, is chronograph them all with the same load. If the longer barrels have significantly higher velocity than the shorter barrels, that would be an indication that the bullet is leaving the muzzle before the powder charge has burned completely, and that load would benefit from a slower burning powder (larger grain size, all else being equal). Conversely, if your longer barrels aren't showing a significant velocity increase over the shorter barrels, that would be an indication that the powder is burning completely, which means you probably have an early pressure spike. I haven't run this experiment personally, so surprise results are a possibility.

 

[brownac1983]

BS who really cares, just shoot. I don't think that anyone is that perfect at shooting all I know that my load of BP, kills deer

My mom killed a deer with an '85 Chevy van. Some of us like a challenge.

 

[Nuthatch]

Yeah, I think that's likely. your bigger surface area due to density and irregular grain shape is giving you a faster burn rate, which would result in reaching peak pressure earlier in the combustion cycle. There should be an ideal grain size where your powder would have approximately the same burn rate as commercial 3F, but it'll take some experimentation to find it. A proper chronograph would be really helpful if you go down that road.

As far as pressure goes, there's not really a great way to know the pressure curve unless you actually instrument a test barrel, but one experiment you could do, if you have access to various guns of the same caliber and different barrel lengths, is chronograph them all with the same load. If the longer barrels have significantly higher velocity than the shorter barrels, that would be an indication that the bullet is leaving the muzzle before the powder charge has burned completely, and that load would benefit from a slower burning powder (larger grain size, all else being equal). Conversely, if your longer barrels aren't showing a significant velocity increase over the shorter barrels, that would be an indication that the powder is burning completely, which means you probably have an early pressure spike. I haven't run this experiment personally, so surprise results are a possibility.

Great thoughts. I now have more experiments to run -- likely AFTER I get my deer.

 

[Johnny Tremain]

weight against the scale on your powder measure?

How about by volume, not weight. They are quite different

 

[brownac1983]

How about by volume, not weight. They are quite different

Grains is ALWAYS a measure of weight. Powder measures are a way of approximating a charge based on an assumed density of 1.72-1.80 grams/cc, which is the standard for commercial powder. That's the purpose of measuring the weight of a charge against the powder measure, to verify the actual charge (in grains) against the powder measure scale. A less dense powder measured to the 75 grain line on a volume powder measure will not be 75 grains of powder, so you have to know your density and adjust your measure accordingly.

Substitutes like Pyrodex are measured by volume, not by grains. They're calibrated to provide an approximately equivalent charge to black powder when measured with a volume scale, although the weight will be different.