Black powder felt recoil?

[Hogpost]

I love the boom and flash and heavy recoil of black powder, but the reason always given for the heavier felt recoil seems incomplete. Absolutely, that 50% of the powder charge that remains unburned and is ejected with the bullet has some effect, but it cannot be all of it. In my 44-40 revolver, for instance, Swiss FFFG feels a whole lot stiffer than Unique, even when the muzzle velocity with the same bullet is similar. But 50% of 35 grns BP is only 17.5 grns, much of which remains in the barrel as fouling. Adding 10-15 grains to the bullet (5-8% of a 200 grn bullet) would not make that much difference in felt recoil.

In my opinion, the other reason is the extremely fast burning rate of BP, resulting in an almost instantaneous "hammer blow", rather than the slightly longer "push" of progressive-burning smokeless. While the total recoil energy (mass x velocity) may be the same, it feels stiffer with BP because it is felt less (in microseconds) gradually.

However, that's just my engineer's guess. Anybody out there have some real information?

[Springfield]

Actually I have always felt the opposite, BP has a softer "push" while smokeless has a sharper Bang to it. BP is usually still burning while the bullet goes out the end of the barrel while smokeless is usually done by then.

[Hogpost]

It's difficult to compare BP & smokeless rounds when the performance of the two loads is different: most smokeless loads provide higher velocity and/or use different bullets. Try 44-40 in a 7 1/2" Colt, the Lyman 427098 bullet: 35 grns FFFG Swiss versus 9 grns Unique. The Unique provides 986 FPS, while the BP gives only 909 FPS, but virtually anyone holding the gun will tell you the felt recoil is noticeably greater with the BP. Try a direct comparison like this, and I think you will see what I mean.

And that orange flame you see exiting the barrel rarely includes any un-detonated powder, unless in the case of an overloaded muzzle loader. It consists mostly of glowing bits of fouling, the hot residue of the burned BP. One of the reasons most indoor ranges will not permit BP shooters is that their floor is littered with unburned "progressive" smokeless, and the falling hot embers of BP may ignite it.

But Springfield, I appreciate your input, and it's not different from many folks I've talked to. I could easily be 'way off base.

[Springfield]

I bet if you downloaded the Unique to equal the BP velocity you would see a difference. I shoot BP in my 45 auto in Wild Bunch matches. I fill the case all the way with fffg and use a 260 grain bullet and the recoil is still much more manageable than any kind of full power smokeless. Maybe all the smoke and noise is making it seem like it has more recoil.

[RMulhern]

I've shot thousands upon thousands of rounds through .45 Colt SAA revolvers with SP and the felt recoil of 37 grs. of FFF BP is more potent on recoil! As for rifles in the 12# class or slightly heavier.....even with the 50 2 1/2 case....the felt recoil...IMO....is nothing compared to the same weight rifle in say a....300 Win Mag with a good 1000 yd. target load!

[NickSS]

I have been shooting black powder in rifles for over 45 years and the last 22 years I have been shooting BPCR matches. That said I will say that the felt recoil is greater using black powder compared to smokeless powder for a given bullet and a given velocity. When shooting my 45-70 with 535 gr postels over 65 gr of FFG after firing 50 rounds prone in a day my shoulder is tender. Shooting the same bullets pushed by AA 5744 at the same velocity firing 50 rounds prone in a day and my shoulder does not feel any affect at all. As a result I never fire heavy bullets in my 45-70 without a recoil shield on my shoulder. Other wise I start flinching on the second day of a two day match. Why this is I do not know but I suspect it is becasue of the greater volume and weight of the gas blowing out of the muzzle gives a greater recoil due to the jet effect of the gas. With smokeless there is less gas so less push.

[Stampede]

I have mixed “feelings” about the BP or Smokeless kick backs.

The kickback with my .45-120SS is very hefty but not unbearably (I love it). But the kick back from my .300WM is way more and my .338LM is in between!!!! Go figure.

There is all so a weight issue with the gun it self. I have three .50-70 (12.7x44R) rifles. My Remington RB is a light weight compared to my RB Husqvarna infantry rifle and kicks therefore even more with the same BP load.

I my experience the BP loads “Push” and the Smokeless “Kicks” more, but hey that’s my opinion.

Peter (Stampede)

[Hogpost]

NickSS & RMulhern, thanks, that's exactly what I'm talking about: with the SAME bullet & velocity (or same total muzzle energy) & SAME gun weight, the BP load always feels seriously heavier.

And I agree with virtually everyone else that the larger mass of ejected BP fouling essentially adds to the bullet weight, which is part of the cause of heavier felt recoil. (Approx 50% of BP charge weight remains as solid material) But I also think the almost instantaneous "hammer blow" of BP combustion, compared to "progressive" SP is an additional factor in the feel.

I'm hoping someone out there has some real data on that because I think many of us would like to know. I sure would!

[TXGunNut]

I've always felt the "push" and "boom" of a BPCR fired w/ BP was more pleasant than an equivalent SP load but NickSS has proved that theory wrong. I don't shoot SP in my BP guns and vice versa so I doubt I'll do any testing on my own in rifles. Thanks guys, interesting thread.

[Chicken Thief]

100degF at 10% hum compared to 100degF at 90% hum. Which is warmer?

See the problem?

You cant compare BP recoil and SP recoil.

BP flamefront moves way way below half the speed of SP. The top speed of bp is somewhere aroung 2000fps and the max speed with SP is over 5000fps.

[Hogpost]

Aw, Cheese, Chicken Thief, let's stay on point here, and stick with real info:

1. FACT: (repeated God knows how many times from hundreds of shooters) using the SAME bullet launched at the SAME velocity from the SAME gun, the recoil from the BP load FEELS heavier.

2. FACT: under the conditions indicated above, one reason is that BP ejects a large mass of solid (fouling) material, roughly equivalent to 50% of the charge weight. This mass is additional to the bullet weight, resulting in an ACTUAL increase of total energy including recoil. (Energy = Mass x Velocity squared). This is one reason for fact #1.

3. Black powder combustion is very very much quicker than smokeless, which is why smokelesss is also called "progressive" burning. SP initially accelerates the projectile at a slower rate than BP, but continues to do so much further down the barrel than BP. Your "flame front" velocities are irrelevant, as SP combustion velocity increases with chamber pressure, unlike BP. Thus, by comparison, BP deals a sort of "hammer blow" to the projectile, while smokeless delivers a more gradual acceleration.

Since #1 and #2 and #3 are FACTS, I wanted to know if there was FACTUAL support for the concept that #3 is an additional contributing factor to #1; and I would dearly like to see some real DATA.

[mustanggt]

The question is "Felt recoil" right? It feels like more force is slamming into my shoulder when I fire a black powder load and I love it. :-D

[Cap'n Morgan]

I love the boom and flash and heavy recoil of black powder, but the reason always given for the heavier felt recoil seems incomplete. Absolutely, that 50% of the powder charge that remains unburned and is ejected with the bullet has some effect, but it cannot be all of it. In my 44-40 revolver, for instance, Swiss FFFG feels a whole lot stiffer than Unique, even when the muzzle velocity with the same bullet is similar. But 50% of 35 grns BP is only 17.5 grns, much of which remains in the barrel as fouling. Adding 10-15 grains to the bullet (5-8% of a 200 grn bullet) would not make that much difference in felt recoil.

In my opinion, the other reason is the extremely fast burning rate of BP, resulting in an almost instantaneous "hammer blow", rather than the slightly longer "push" of progressive-burning smokeless. While the total recoil energy (mass x velocity) may be the same, it feels stiffer with BP because it is felt less (in microseconds) gradually.

However, that's just my engineer's guess. Anybody out there have some real information?

I simply believe the difference is due to accelerating a larger mass (boolit+powder) over a shorter time. Even with everything else equal, the extra 28 grains when comparing 35 grains BP to 7 grains Unique will increase recoil 20%. I don't think the "rocket effect" at the muzzle has any significant effect on recoil in a low pressure round like the 44-40.

[montana_charlie]

It might be a 'fact' that hundreds say BP recoils harder, but I doubt that those 'hundreds' obtained their findings by shooting identical rifles, to test their similar loads.

Because 'felt' recoil is the critera, all kinds of extraneous factors enter into this pointless discussion. Rifle weight, balance, buttpad, even the shape of the buttstock is material to how the recoil 'feels'.

If there is a machine that can produce the 'hard facts' that you are asking for, it's output would not take 'feelings' into account.
Therefore, while you might have a scientifically provable 'number' for your records, you would still get argument from human shooters.

CM

[plourbag]

Stampede, I notice your comparing calibres. I've only started using BP loads in my 45/90 and haven't cronographed them to compare them to smokeless but I find smokeless much more comfortable with the same projectiles and as much FFg as I can compress in the case without distorting it. However, I have shot a lot of large calibre smokeless "African" calibres in my mispent youth and found that gun weight and stock configuration have a heck of a lot of effect on perceived recoil. I have had rifles in the same calibre, shooting the same ammo; one was extremely comfortable and the other crossed my eyes(I had a .505 Gibbs that I could only sell to someone I disliked). I'm not recoil sensitive (my mates reckon I'm a masochist). I notice others on this post use the same rifle for BP and smokeless so my comment only refers to your post. Anyway, shoot whatever you're comfortable with as long as it hits where you're pointing. After all it's the most fun you can have with your pants on.

[redneckdan]

One of the reasons most indoor ranges will not permit BP shooters is that their floor is littered with unburned "progressive" smokeless, and the falling hot embers of BP may ignite it.



I have seen this happen first hand, it is a pretty interesting occurrence.



I bet if you downloaded the Unique to equal the BP velocity you would see a difference. I shoot BP in my 45 auto in Wild Bunch matches. I fill the case all the way with fffg and use a 260 grain bullet and the recoil is still much more manageable than any kind of full power smokeless. Maybe all the smoke and noise is making it seem like it has more recoil.

Interesting. Is holy black required for the wild bunch match? Does it cycle your 1911 okay with a stock recoil spring?

[Hogpost]

By the way, the specific data I would like to see is related to my original question about the combustion rate of BP being faster than smokeless: surely someone out there has come across some charts or graphs of pressure over time while the bullet is in the barrel, comparing BP versus smokeless.

[LazyJW]

By the way, the specific data I would like to see is related to my original question about the combustion rate of BP being faster than smokeless: surely someone out there has come across some charts or graphs of pressure over time while the bullet is in the barrel, comparing BP versus smokeless.

Way back in the foggy reaches of my caffeine crazed memory banks, I recall an article in Guns & Ammo(?) by Ross Seyfried (I think). Very foggy, so I'm not going to be too adamant.

Short story: said article showed pressure traces of Black Powder versus Smokeless. BP had a significantly SLOWER pressure curve rate, contrary to popular belief. The pressure rose much slower, peaked lower, and ended later.

This was some years back, and I doubt that I saved the article, just working on memory here.
Joe

[Springfield]

BP has a lower and slower pressure curve. Just read any article about shooting Smokeless in an old Damascus barrelled shotgun the the charts come out of the woodwork. They all say the opposite of you, the smokeless peaks way sooner than BP, thus the danger of shooting a smokeless shotgun round in a BP designed barrel and blowing it up. And no, BP is not required, nor even recommended for Wild Bunch matches. My stock 1916 Colt 1911 works fine as long as I use a heavier than normal bullet, as the BP doesn't provide a sudden enough push to work the slide otherwise.

[Ed in North Texas]

Aw, Cheese, Chicken Thief, let's stay on point here, and stick with real info:

1. FACT: (repeated God knows how many times from hundreds of shooters) using the SAME bullet launched at the SAME velocity from the SAME gun, the recoil from the BP load FEELS heavier.


Since #1 and #2 and #3 are FACTS, I wanted to know if there was FACTUAL support for the concept that #3 is an additional contributing factor to #1; and I would dearly like to see some real DATA.

There is the problem. "...the BP load FEELS heavier." You are trying to get an answer which quantifies a subjective determination.

[Greg Mercurio]

For Hogpost:

The mass of ejecta, burned or unburned is equal. Mass of gas or mass of unburned BP is the same regardless of state. The only way to increase the mass of the ejecta is to add mass to the bullet or the powder. It can't magically happen at ignition.

I'm also challenging your statement that BP has a faster burn rate than SP. If it's true that BP ejecta is 50% unburned, by definition the burn rate is in fact slower than SP, as the burn "event" is of much shorter duration with SP. Not sure I could make the claim that 50% of the ejecta in an SP charged rifle is coming out of the barrel unburned. I suspect pressure/time curves would prove this out.

But that's just my opinion. YMMV. :popcorn:

[Greg Mercurio]

My suspicion on felt recoil is that the BP event duration creates the impression of a larger thump than with SP, even though the G-forces applied to your shoulder are roughly equvalent. The math doesen't change whether it's BP or SP. Mass is mass. Yes there is a velocity differential, and that is also perhaps even more causal than the mass component of the equation, but it's late, and I'm hugry, and not inclined to dig out the calculator to run "what-ifs".

You can test this endlessly here:
http://www.handloads.com/calc/recoil.asp

In terms of the dreaded physics, the human body percieves G-loading very differently than a lab instrument. You might not even feel a G-load of 15G's for 15 milliseconds, but spread that same 15 G's over 300 milliseconds, you will perceive all manner of different sensory inputs. The Air Force did a ton of Human Factors testing over the years after WWII to determine how the body responds to G's as the piston aircraft were replaced by the first generation of jet fighters. Most if not all of it is available if anyone wants to pore over old data.

Just one old coot's opinion, nothing more. :drinks:

[LUBEDUDE]

I normally shoot smokeless in cowboy matches. But when I do shoot BP, wow, what a breeze. It feels less to me, more like a push than a snap.

Don't care what the facts are, recoil is all subjective.

[RMulhern]

Anyone that can't stand the felt recoil of a BPCR needs to stick to a .22 LR!!

[hepburn45110]

I have a Highwall in 40/65. I use a 370gr bullet and breech load 1/16 ahead of the case with black or smokless. The gun is loaded for 1260fps with both powders. A 50 shot match with smokless is not unpleasant. A fifty shot match with black is much more tiring. With black, the initial shock is a bit softer but it lasts longer. The rifle moves back further and twists a lot more making it more difficult to control with black. I think that the burn characteristics and powder colum weight of black cause this.

[bigted]

here is a fun thing to do when you try to pass off the "mass is mass" theory.......

load a 45-70 case with 50 grains of 3031 behind a Lyman 457125 520 grain boolit.

now load this same boolit with 50 grains of 2 f black powder and fill the rest of the case with cornmeal to the bottom of the boolit so it compresses the column around 1/8th inch.

now take your trusty Ruger # 1 out side and shoot the bp load first.......then touch off the 3031 load after and reply which one "felt" heavier.

mass is mass indeed...may make sense on paper but lacks something in reality.

[Hogpost]

Dang, Greg, you are absolutely right! I had forgotten my high-school physics: gas is mass. Apparently so have some prominent writers like Randfy Wakeman (ChuckHawks) who says "“Black powder and black powder substitutes are horrifically inefficient propellants; fully half of the powder charge does not change to gas, remaining a solid all the while. That gets pushed out your muzzle as well, and adds to recoil.”

So it's the full powder charge mass that is additional to the bullet weight, not just a part of it. (Although not all of it will exit the muzzle at the same velocity as the pressure drops quickly when the bullet exits, and some of the crud, as we all know, remains in the barrel as fouling.)

That's actually a better, more complete explanation of why a BP charge, ejecting the SAME bullet at the SAME velocity, provides measurably greater total recoil: it's the difference between 9 grns Unique and 38 grns FFFG in a 44-40.

(Again, this all refers to same bullet weight, same velocity: a SP load providing higher velocity, or using a heavier bullet, is apples-to-oranges.)

As to the burn rate of BP, what I meant by "unburned" refers to the chemical inefficiency of BP compared to smokeless: a higher percentage of the original charge remains as solid matter (fouling). I still believe that BP generally combusts more quickly than "progressive" SP, with the pressure generally peaking earlier; but I could easily be wrong, and there are undoubtedly exceptions in both direction. I'll try a couple of powder companies, and see what they say.

Thanks all of you for your inputs!

[Jeff Houck]

Here is the formula for recoil:
2
[(wght of bullet)x(mv)+(wght of powder charge)x(4700)] /64.348)x(wght of gun)

Weight of bullet is in pounds
Velocity of the bullet in fps
4700 is the velocity of the gas in fps
Weight of powder charge is in pounds

example 1 – smokeless powder (Unique)
500 gr. bullet = .0714285 lbs.
15 gr. powder = .0021428 lbs.
2
[(.0714285 lbs.) x (1150 fps) + (.0021428 lbs.) x (4700 fps)] / (64.3480) x (12 lbs.)

2
[82.14 + 10.07] /772.18

2
[92.21] /772.18

8503.41/772.18

11.01 lbs recoil

Example 2 – black powder
500 gr. bullet = .0714285 lbs.
70 gr. Powder = .010 lbs.
2
[(.0714285 lbs.) x (1150 fps) + (.010 lbs.) x (4700 fps)] /(64.3480) x (12 lbs.)

2
[82.14 + 47.0] /772.18

(16677.91)/772.18

21.60 lbs recoil


So there is almost twice as much recoil from the black powder load verses the smokeless loads of the examples. The difference is in the amount of recoil generated by the mass of the two powder charges:
15 grs. of smokeless = (.0021428 lbs.) x (4700 fps) = 10.07 lbs fps
70 grs. of black = (.010 lbs.) x (4700 fps) = 47.0 lbs fps

[Jeff Houck]

O k - so much for the posts maintaining the correct formating.
the "2" that appears on it's own line is actually the square that should be above the numerator line in the equation.
it should be: [(wght of bullet x velocity)+(wght of powder charge x 4700)] quantity squared. divided by the (wgt of the gun) x (64.348) = recoil

[Multigunner]

Well Black Powder is a Class A explosive, I figured its explosive rating compared to smokeless powder was due to its burning rate. A cardboard container of BP will explode when the same container of smokeless will only burn. Thus the more stringent requirements for storing BP even though less energetic per weight.

Older BP era shotgun barrels often have much thinner walls from a point past the chamber to a point before the muzzle. I think the term is "swamped". Gunmakers used this as a weight reducing measure for double guns. They could get away with it because the power curve of the BP charge peaked early. This is cited as a reason for otherwise strong BP era barrels splitting when smokeless powder loads were introduced.
It could be that the difference was only with early smokeless formulas that had many other incompatability problems.

Grain size and coatings determine burn rate of BP powders, smokeless burn rates are more due to formula and additives, though grain size remains a very important factor.
The surface coating of BP grains is a product of the solvent used in mixing. French powders were mixed using wine instead of water, natural polymers in the wine formed a moisture resistent coating on the surface of the granules as it dried. Don't know what modern manufacturers use to obtain this effect.

[Hogpost]

Perfect, Jeff, thank you!
I was curious about the selection of 4700 fps for gas velocity, so did some investigation:

"The NRA Fact Book (1988) gives some estimates for (gas velocity). For small arms, the gas velocity is about 4000 fps for smokeless and about 2000 for blackpowder. For cannons 4700 is used. Other references give only the 4700 fps figure."

"In the British Textbook of Small Arms (1929) it is suggested one make the propellant's velocity proportional to the bullet's: V = ( b + k*c ) * v / W

Unfortunately, the value of k was found to vary and "lies between 1 and 2, with an average value of 1½." If one uses that 150%, this equation at a muzzle velocity of 2700 fps gives the same results as the 4000 fps number cited in the NRA book. It seems reasonable to me the propellant's velocity will be related to the bullet's, but the fixed 4000 fps term gives a slightly better agreement with the recoil computations from the internal ballistics simulator QuickLOAD."

So, 4000 to 4700 seems about as close as one will get for smokeless, but the intimation is that it will be slower for black powder. Nevertheless, the difference will not be vast, and the formula points directly to the higher recoil from BP for th same bullet at the same velocity.

Cool!

[OD#3]

I got a "kick" out of the posts that suggested BP loads actually recoiled less and that the "felt" recoil was subjective opinion based on the timing of the total applied recoil load. I think that the ones posting these opinions must shoot only BP cartridge rifles. Were my only experience with BP cartridges limited to my .45 Colt-chambered model '92 replica, I might even agree. But with revolvers, my load of 40 grains FFF behind a 255 grain pill feels like a magnum load in my 7.5 inch barreled Colt SSA even though velocities rarely break 1,000 f.p.s. And even though I'm getting less than 650 f.p.s. from my load of 18 grns. FFF behind a 265 grain pill in my .455 Webley (actually .45 ACP, but I load it as if it were a .455 Mark I), the recoil is much stouter than I get with mild smokeless loads producing the same velocity. The recoil I get with black powder is so much higher than comparative smokeless loads, that I have even wondered if it was more punishing to the firearm than a smokeless load--despite the lower pressure. I've often wondered about the possible irony of my trying to "baby" my Webley Mark I revolver by using only low pressure black powder loads only to have it suffer damage of another kind by increased battering from recoil.

[ColColt]

I once had a Navy Arms Rolling Block half round/half octagon carbine in 45-70. I'd occasionally use about 65 gr of 3fg best I recall behind a 405 gr lead boolit and it seemed to "push" more than smokeless powder but not snappy like smokeless. I got the same feeling using BP with the 45 Colt but what a joy to shoot!

[juniorsonic]

I know this may sound like a cliche, but I have always found the 'recoil' from BPC guns (especially rifles) to be very much more of a big, somewhat slow "PUSH", rather than the sharp "kick" or "punch" of smokeless magnum-powered numbers. But that's just me.

[RMulhern]

Those that claim/bitch about recoil must be young and tender!!

[juniorsonic]

Those that claim/bitch about recoil must be young and tender!!

Yeah! "Recoil?" What's that? Well, to ME, "recoil" is merely the feeling of absolute proof that I am launching something capable of inflicting MANY ft-lbs of energy into/on anything in its path!:twisted:

[Catlow Jack]

I know this discussion occurred over three years ago, but I'm new to the group and find this to be very interesting. This issue could probably be addressed objectively by running tests employing the use of transducers, specifically piezoelectric accelerometers, and a Tektonix 754C, 4-channel, digitizing oscilloscope (with color display). I believe I could set up and run the experiment, and provide some definitive answers in graphical form (force vs. time) if only someone would send me enough money to cover the cost of the equipment I'd need. $50,000 would probably be sufficient. Oh, and maybe you could also send a brand new Shiloh Sharps Rifle (Quigley Model) chambered for, say, .45-110, as a test rifle ... strictly in the name of science, mind you. I'd be happy to share the data ... and keep the rifle.

[Win94ae]

My black powder 50 cal rifle shots a saboted 250gr projectile about 1650fps. It feels a lot like the kick of my 44mag rifle propelling a 240gr projectile at 1700fps.

[M-Tecs]

I was always aware that the bullet weight and powder weight needed to be added together to calculate the total mass ejecta but I never fully understood how noticeably this effected felt recoil until I built three identical 6mm matches rifles. The chambering’s where 6mm BR, 6mm XC and 243 Winchester. The rifles weight was within 1 1/2 oz.’s of each other. When pushing 105/107's at the same velocity it was easy to feel the increase in powder weight in felt recoil.

[Hogpost]

Mr Catlow, sir: by any chance do you work for Da Gummint?

[JonnyReb]

I know this discussion occurred over three years ago, but I'm new to the group and find this to be very interesting. This issue could probably be addressed objectively by running tests employing the use of transducers, specifically piezoelectric accelerometers, and a Tektonix 754C, 4-channel, digitizing oscilloscope (with color display). I believe I could set up and run the experiment, and provide some definitive answers in graphical form (force vs. time) if only someone would send me enough money to cover the cost of the equipment I'd need. $50,000 would probably be sufficient. Oh, and maybe you could also send a brand new Shiloh Sharps Rifle (Quigley Model) chambered for, say, .45-110, as a test rifle ... strictly in the name of science, mind you. I'd be happy to share the data ... and keep the rifle.

Lol, welcome to the forum Jack. :drinks:

[Paul_R]

All I know is that my BPCR kicks a lot more like it does now than it did before...[smilie=s:

[montana_charlie]

I know this discussion occurred over three years ago, but I'm new to the group and find this to be very interesting. This issue could probably be addressed objectively by running tests employing the use of transducers, specifically piezoelectric accelerometers, and a Tektonix 754C, 4-channel, digitizing oscilloscope (with color display). I believe I could set up and run the experiment, and provide some definitive answers in graphical form (force vs. time) if only someone would send me enough money to cover the cost of the equipment I'd need. $50,000 would probably be sufficient. Oh, and maybe you could also send a brand new Shiloh Sharps Rifle (Quigley Model) chambered for, say, .45-110, as a test rifle ... strictly in the name of science, mind you. I'd be happy to share the data ... and keep the rifle.
That was covered in Post #14.
http://castboolits.gunloads.com/showthread.php?126586-Black-powder-felt-recoil&p=1388021&viewfull=1#post1388021

[Lead pot]

To know what to know what a black powder rifle feels like compared to a SP rifle you just have to shoot it and not just pull it out of the closet a couple times a year and load it with black and not the usual smokeless that most use.
When the big .50 Shiloh gets set off with a 720 gr bullet and 118 gr of 2F it gets your attention like Thor's hammer hitting you with a quick 60 lbs.
Sorry I never loaded it with smokeless so I cant compare it.
But not much unburned powder gets on the ground :shock::bigsmyl2:
http://i704.photobucket.com/albums/ww43/Kurtalt/44bastjpg-1.jpg (http://s704.photobucket.com/user/Kurtalt/media/44bastjpg-1.jpg.html)

[Ballistics in Scotland]

In all types of firearm a load with a substantial charge of black powder does give higher recoil, measurable with a dynamometer, than smokeless of comparable performance.

Three facts are vital here.

The first is that up to the missile and charge leaving the muzzle, equal momentum is imparted to the gun and to the ejecta, i.e. missile, powder and wads, which are projected in a forward velocity. (Momentum is mass times velocity, and energy is mass² times velocity, which is why a small, fast bullet gives much less recoil than a slow, heavy one with the same energy.)

For this purpose it doesn't matter in the slightest whether the charge part of the ejecta has burned into gas or not. All that matters is their weight and the speed they have reached.

The second is that if black powder and smokeless powder dispatches the same missile from the same length of barrel at the same velocity (as they are extremely likely to do in shotguns and large-caliber conventional pistols), the average acceleration imparted to the ejecta, up to reaching the muzzle, has been the same. If one gave higher early pressure, contributing to that acceleration, it must have given lower pressure further down the bore. Most likely, although not inevitably, it gave the higher maximum pressure.

The third is that at the muzzle something quite different is added. The escaping gas exerts a so-called jet effect, and just like the air escaping from the released neck of a balloon, it doesn't depend on prior velocity (zero in the case of the balloon.) It is purely a function of the pressure difference inside the barrel at the moment of emergence, and on the outside. General Hatcher found that he could bring this jet effect fairly accurately into recoil calculations, for a military rifle like the M1903, by pretending the powder charge was 1.75 times what it really was.

Just as with space rockets, it isn't exerted by pressing on the air, and would work even better in a vacuum. It occurs because the pressure on the rear of the cartridge case suddenly becomes unbalanced by pressure on the rear of the bullet.

The relation of black powder and smokeless in speed of pressure buildup is more complicated than has been suggested here. Basically every powder has a burning rate, i.e. the speed at which the successive layers from the outside off the grain inwards will burn away. If you ignite a little powder in the open, you will find out that for equal grain size black powder burns much faster. Even so, it will take many times the length of time which a bullet takes to reach the muzzle.

But every powder, again, increases its burning rate as pressure on it rises. With black powder the burning rate is approximately proportional to pressure. But with smokeless it increases much more than pressure does. Put simple, it means that anything you might do to increase pressure (bullet weight, fit to the bore, hardness etc.) may increase pressure moderately with black powder, but immoderately with smokeless.

The most frequent situation in real-life firearms practice is for black powder to build up to its highest pressure further down the bore, and fall away from it later. The peak pressure of smokeless will usually but not always be higher, but on a graph it will be an abrupt shark's-fin peak, while the black pressure graph will be a lengthy, rounded mountain of less height. Another way of saying what I did about average pressure above, is to say that the acceleration imparted to the bullet is proportional to the area under the pressure-against-distance graph. It is perfectly possible for black powder to have terminal and peak pressures both lower than smokeless, and yet yield equal results.

A final complication with black powder is that pressures may run higher than those intended when the barrel becomes heavily crusted with fouling. Smokeless fouling is less significant, but may even act as a very slight lubricant.

[rfd]

lots depends on how any firearm that is expected to have some significant recoil is approached. so, and fwiw, as a right hander i have a recoil sensitive and chronically "frozen" right shoulder. so i need all the help i can get with recoil and my bpcr rifles. my pedi .45-70 roller weighs in at just about 13.5lbs and i've added a kick killer "acton" lace-on recoil pad. though i've shot lighter and heavier loads, my typical cartridge is 68 grains of slightly compressed swiss 1-1/2f under a 523 grain money bullet - i can fire that all day long (and have, for well over 100 rounds), and not feel a thing during or after the day's shooting. ymmv.

[cajun shooter]

I love the boom and flash and heavy recoil of black powder, but the reason always given for the heavier felt recoil seems incomplete. Absolutely, that 50% of the powder charge that remains unburned and is ejected with the bullet has some effect, but it cannot be all of it. In my 44-40 revolver, for instance, Swiss FFFG feels a whole lot stiffer than Unique, even when the muzzle velocity with the same bullet is similar. But 50% of 35 grns BP is only 17.5 grns, much of which remains in the barrel as fouling. Adding 10-15 grains to the bullet (5-8% of a 200 grn bullet) would not make that much difference in felt recoil.

Hogpost
In my opinion, the other reason is the extremely fast burning rate of BP, resulting in an almost instantaneous "hammer blow", rather than the slightly longer "push" of progressive-burning smokeless. While the total recoil energy (mass x velocity) may be the same, it feels stiffer with BP because it is felt less (in microseconds) gradually.

However, that's just my engineer's guess. Anybody out there have some real information?

Hogpost, I wish I had posted on your OP, old eyes looked past it I guess. I will have to disagree with your posting where you say that BP burns faster than that new stuff they use. Everyone who shoots BP knows that it burns from the outside in and it's grains are of many different sizes and shapes. Why are the barrels of BP guns made out to 34 inches while smokeless guns are as short as 16 inches for rifle barrels for the SP powders?
Most all of the loaded shotgun shells made today will burn their greatest energy within the first 13 or so inches of barrel. If you tried firing a BP shell in a SG with that length of bbl, the results would be poor at best. The reason is that the SG BP powder takes longer to burn completely enough to deliver the needed energy to send the shot charge out of the bbl and therefore needs the longer bbl.
For many years when I was a young kid and going to the hunting camp, all I heard was that you had to have a SG with a 30 inch bbl to hit them ducks. When I asked why, I was told so that the powder has time to burn son. This was a old tale that resulted from the BP days of shooting and before the true ballistics of SP was known by the common man. I'm sure that everyone remembers those days back in the 50's and 60's if they are in my age group. I was told unless you had that Browning with that 30 inch bbl you are not going to kill anything.
I shoot nothing but BP for the last 6 or more years in my SASS matches with the 44WCF. I shoot full cases of powder and at times shoot cases with 40 grains of KIK 2F.
I was a POST Certified Firearms Instructor for a Metro force of over 1200 officers along with the training of all the area smaller departments. I also conducted training at LSU's Law Enforcement Institute. During this training, I will have to say that unless you have a controlled testing that meets many standards, you can't make a blanket statement about felt recoil. Later David

[Hogpost]

Cajun Shooter (David), sir, with respect: I did not make a blanket statement, I voiced an opinion. I then noted even it was a guess, and asked for input from anyone with real information.

I still have yet to see any real information, such as proper technical explanation or direct comparison of measured firearm internal pressure curves smokeless vs black.

Until I see such comparative pressure curves, I will stand by my opinion that black powder in a firearm burns much faster than smokeless. Indeed, blackpowder burns so rapidly that it actually explodes even with minimal confinement, and therefore unlike modern smokeless powders it is classed as an "explosive", which requires special handling, shipping, and storage arrangements.

As a graphic example, even if a bit off the path, I suggest you watch this YouTube video: https://www.youtube.com/watch?v=icsbtkYpfBw

I would also take issue with your notion of barrel length being a function of powder burn rate. Both smokeless and black are done burning well before the bullet leaves the barrel, and any further acceleration is from the bullet using the existing (and dropping) pressure. Smokeless simply builds pressure for a great distance more than black, but in either case a longer barrel uses whatever pressure there is for a longer period of time, enhancing muzzle velocity.

Notice that those old black powder shotgun barrels are so much thicker at the breech than the muzzle: BP pressure peaks very quickly, and because burning has been completed, pressure drops as the shot moves further down the bore. Smokeless shotgun powders are relatively fast burners, to match as closely as possible the BP they replaced; but they are still far slower than the black, which is why firing a smokeless shell which exactly matches the muzzle performance of the BP shell, in a black-powder shotgun results in blowing out the barrel at least half-way or further up from the breech.

But David, you and I, and others on this forum, will continue to disagree in a friendly manner until someone can show us real comparative measurements of internal pressure curves, from controlled testing as you most correctly say.

Respectfully,

Jim

[Chill Wills]

Hogpost, Two thumbs up for showing class with a respectful post!

As you say, "Until I see such comparative pressure curves, I will stand by my opinion that black powder in a firearm burns much faster than smokeless."

So, I can not post any pictures of time pressure traces with out much digging but I think if or when someone does they will show that the range of smokeless powders available to handloaders bracket the burning range of black powder, both slower and faster; some smokeless powders are even slighter faster than 4Fg and a lot of the medium and slow smokeless powders are slower to much slower than the coarsest BP. The total range of relative speed in the smokeless group is much broader than the BP.

The various powders time/pressure traces are fun to compare and contrast and really help, at least help me see visually how these different powders compare. I hope someone will take the time to post a link to some.
Michael Rix

[BrentD]

http://img.photobucket.com/albums/v497/3855Win/45_70_pressures.jpg
http://img.photobucket.com/albums/v497/3855Win/45_70_pressure3.jpg

[Chill Wills]

Wow Brent! And just like that are a good set of visuals.

[montana_charlie]

Until I see such comparative pressure curves, I will stand by my opinion that black powder in a firearm burns much faster than smokeless. Indeed, blackpowder burns so rapidly that it actually explodes even with minimal confinement, and therefore unlike modern smokeless powders it is classed as an "explosive", which requires special handling, shipping, and storage arrangements.
I have always agreed with the opinion that you hold, but based mine on what happens to a lead bullet when fired with the two propellants.

It is a given ... or a rule of thumb ... or a foregone conlusion ... or everybody knows that a bullet diameter must be greater than groove diameter when shooting cast bullets over smokeless powder.
If 'the golden rule' is not followed, bore leading and bullet deformation due to gas bypass is to be expected.

On the other hand, it is commonly known that a soft bullet smaller than groove diameter can be expected to 'bump up' quickly enough to seal a bore before it even moves out of the cartridge case ... if black powder is the propellant.

So, I may not know what the powder does, but the bullet does ...

[Hogpost]

Good point, Charlie. I shoot a number of BP cartridge guns with off-the-wall bores (like 43 Spanish Reformado and 11mm Danish)
where I depend on that BP bump-up because I cannot get bullets of the proper size.

[Chill Wills]

I have always agreed with the opinion that you hold, but based mine on what happens to a lead bullet when fired with the two propellants.

It is a given ... or a rule of thumb ... or a foregone conlusion ... or everybody knows that a bullet diameter must be greater than groove diameter when shooting cast bullets over smokeless powder.
If 'the golden rule' is not followed, bore leading and bullet deformation due to gas bypass is to be expected.

On the other hand, it is commonly known that a soft bullet smaller than groove diameter can be expected to 'bump up' quickly enough to seal a bore before it even moves out of the cartridge case ... if black powder is the propellant.

So, I may not know what the powder does, but the bullet does ...
Exactly Charlie. If the time/pressure curve exceeds the elastic value of the alloy the bullet bumps up. Smokeless or black will do it. You may not choose to use some powder and bullets combination for what ever the preconceived reasons but that is not to say all smokeless is slower nor will not bump a cast bullet up to take the rifling like black does.
Michael Rix

[machievelli]

The formula assumes you know the projectile velocity. I am trying to create a blackpowder version of a rifle grenade in a story, and honestly do not know how to work out that velocity. I tried using the 40mm grenade from an M79 (250 fps) with a powder load of 110 grains, but ended up with a value of 294 ft-lbs.