My local gun range had a meet today for those who wanted to try black powder guns. A few generous guys brought their guns, bullets and powders for us to try. it was a lot of fun though pretty smoky. I loaded and shot a couple of rifles powered by percussion caps and one with a flintlock and also a couple of pistols. I was surprised to see that the rifles are pretty accurate with very light triggers. They will do this again every month or so. I could see myself getting into the sport.

fun, isn't it? BP always draws a crowd

How is the recoil? They seem fun, but I don't know anyone with one.

Recoil ain’t the same when you have a +40” barrel with slow burn black powder. It’s kinda like launching a model rocket from your shoulder if you can imagine. Yeah... kinda like that.

notice how BP brings out the hillbilly in people. "ain't." ya-hooo!
black powder burns slower than smokeless, so the recoil is not as sharp. same force, spread over a longer time. i'm sure our physics guys can splain it better, with nummers an sience an ... stuff. try it, you'll like it.

K9s wrote:How is the recoil? They seem fun, but I don't know anyone with one.

Low, slow “thumps” is the most I’ve ever felt. like a gentle two finger push by someone politely making a point.

No time for one of my more detailed answers.

See my 'Mea Cupa' farther done. Sorry I was in such a hurry.

See:
https://sciencing.com/calculate-force-i ... 17983.html

It explains that the Force of Impact (usually called a"J" moment) is basically Energy/distance traveled.

You can cancel out many of the variables ask similar. Bullet weight, distance of the push back against your shoulder.

The one big variable is the second divisor in acceleration (V^2). In English, we describe acceleration as distance "per second -per second" which is mathematically easier to grok than distance per second squared. The first "per second" is the existing velocity of the bullet leaving the barrel. The second "per second" is how long it took to get to that speed.

Some will say the bullet weights makes big difference, but it is dwarfed by the effect of velocity squared.

Black Powder: 650 grains x 1000 feet/second/.10 seconds (It takes black powder a long time, 1/10th second to get to 1000 ft/second velocity. You can actually see the time delay on a 30fps video - it takes 3+ frames for the bullet to exit.


.308: 150 grains x 2800 feet/second/.010 seconds (or faster). You cannot catch the bullet leaving the barrel in a 30fps video.

So, using the rather odd units of grains*ft/s^2. (divide by 2 for KE as KE= 1/2 M*V^2)

BP: 3.25 million "units" of energy (464 in pounds)
.308: 21 million "units" of energy ((3,000 in pounds)

So a 50 caliber black powder rifle. has a "kick" of less than 1/6th of a .308 - and from my personal experience, that is about right. It feels more like a shove than a kick.

That long time from ignition to bullet exit requires better total control of the point of aim also.

max129 wrote: Tue May 21, 2019 4:38 pm No time for one of my more detailed answers.

Something is wrong with that math. My shoulder says it’s off somewhere.

The 50 cal pistol I shot had less kick my Bersa .380

Totally, but a 650 grain bullet (lots heavier than a 50 cal round ball which is like 175 grains) over BP going 1000 FPS definitely moves your shoulder more than a 308.

Ouch - I really screwed that up. I was in the middle of two divergent methods, was late for a meeting and hit submit when I should have deleted it.

First, I was trying to simplify the problem down to the differences between the two events (Smokeless powder vs Black powder). And I got one part very right: It is the total time the event takes that makes the recoil difference. And I had another basic idea right, that you can cancel out many differences: Same basic rifle weight, same shoulder to push, etc.

Measuring perceived impact is neither a pure Force event not a pure Energy event. It is a (fast) Work event. And measuring Work can be tricky.

In a lab, we would set up two rifles and two identical resistance weights to model the shoulders. Then we would film them both at very high speed and plot two key things: (1) How long did the total event (recoil absorption) take; (2) What did the event curve look like.

The event with the highest peak curve (instantaneous Work per second) would have the highest perceived impact.

Neither Force nor Energy can quite get you there.

And I was in such a hurry, I switched from Force to Energy in mid calculation. (I do better math when drinking than in a hurry.)

F = M*A - my attempt at force was decent on the "A" Acceleration = feet/second/second. But the M is dubious. I was trying to calculate based on the bullet Mass, but there is no telling how much of the actual blast goes into moving the bullet and how much goes into noise, heat and lost gas. Probably almost impossible to measure. (The lab equipment to measure this kind off event is called a "bomb" for a reason.)

KE = 1/2 M*V^2 has the same challenges. What "M" to measure. So none of my shorthands was going to get you there, and I apologize to those who wasted time trying to make sense of my incorrect methods.

Sorry about that ...

While simplifying the numbers might not be obvious, generally think of a 50 cal roundball BP frontstuffer as much like a 45 Colt Carbine in power and mild recoil. Easy shootin.

54 caliber heavy conical bullets and heavy charges of powder start to approach more modern hunting rifle levels of recoil.

Marlene, I'll go with what your shoulders tell you. My experience with black powder is personally mostly revolvers. The few rifles I have shot (what was a total HOOT) were likely not loaded with much powder.

My experience is that round ball weights are so low per caliber that you need a LOT of powder to get any appreciable recoil. Once you go to cylindrical bullet shapes, then you can get up to bigger levels of whump.

i used to describe it thus: "black powder gives you a shove, modern powder gives you a punch".
anyway, it's fun and pleasant to shoot. you learn to love the smell.
the part i did, american civil war, was especially pivotal in firearms history. some of it transitional, now obsolete because they made further advances possible. percussion ignition, hollow based conical bullets, breechloaders, metallic cartridges... names were made that we still use today, berdan, sharps, winchester... i find it fascinating, and urge everyone to give black powder a try. even if you don't like it, you'll have a better perspective and understanding of firearms, technology, history, language... the whole thing, lock, stock and barrel. keep your powder dry!