Posts Tagged ‘bullets’

Ballistic coefficient: What is it? Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

This report addresses:

• Definition of ballistic coefficient (BC).
• How are BCs determined?
• Bullets and pellets have an additional factor.
• BCs are not constants.
• BC is an expression of how much velocity is lost in flight.
• How to cheat the BC numbers.

If ever there was an elephant in a room full of airgunners — this is it! Ballistic coefficient. It seems like everybody talks about it, but what does it mean?

Definition
Ballistic coefficient (BC) is the measure of a ballistic projectile’s ability to overcome air resistance in flight. It’s stated as a decimal fraction smaller than one. When diabolo pellets are discussed, the BCs are very low numbers in the 0.010 to 0.045 range because diabolos are purposely designed to slow down in the air. Their wasp waists, flared skirts and hollow tails all contribute to very high drag that rapidly slows them down — much like a badminton birdie. Lead bullets, in contrast, have BCs between 0.150 and 0.450.

lead bullet comparison
The long lead bullet on the right has a higher BC than the short fat bullet on the left. When they’re both fired at the same speed, the bullet on the right will not slow down as fast as the bullet on the left.

How is it determined?
To physicists, BC is a function of mass, diameter and drag coefficient. This set of parameters seems simple until you examine it closer. A round ball made of pure lead should always weigh the same, as long as the diameter is the same. But a diabolo pellet is conical in shape and can be much longer than the diameter of a round ball of the same caliber. Depending on how the pellet is designed (i.e., how hollow or solid it is), it can also be much heavier because it contains more lead than the ball.

Bullets and pellets have an additional factor
For pellets and bullets, there’s an additional factor to consider — shape. For that reason, there’s a separate definition for the ballistic coefficient of bullets that takes into account the sectional density dictated by the form or shape of the projectile.

I’m purposely avoiding any discussion of BC that includes formulas. Stated simply, a pellet or bullet with a high BC (a large number) will continue to fly much longer than a pellet or bullet with a low BC: A high BC means the pellet will fly farther!

BCs are not constants
Okay, you say, that’s exactly what I want! Give me only those pellets that have high BC numbers.

Not so fast! However, as the velocity of a projectile changes, so does the projectile’s BC. BCs are not constants. There’s no such thing as a pellet with a BC of 0.035. But there are plenty of pellets that will achieve a BC of 0.035 at a certain velocity. When a BC is given, it means something only if the velocity at which that BC was obtained is given with it.

This could get confusing, couldn’t it? Yes, it can be confusing if you try to force numbers onto pellets when they don’t apply. But when you understand that the BC of a pellet is actually a sliding scale, you begin to understand the ballistics of airguns.

BC chart
The ballistic coefficient of a single pellet can change this much with velocity changes.

Who cares?
So what? Who cares about all this sliding scale stuff? You do, and I’ll tell you why. Let’s say there’s a pellet with a BC of 0.042. Wow! That’s a very high number for a diabolo pellet! I’m gonna get me some of them!

Hold on, pardner. What if I told you that pellet was the JSB Exact King in .25 caliber, and that it has that BC only when it’s moving at 1,250 f.p.s.?

BUMMER! You don’t own an air rifle that will propel a .25-caliber JSB exact King up to 1,250 f.p.s. In fact, almost no one does. Therefore, the fact that the pellet has that high a BC at that particular velocity does nobody any good.

If you think about this for a moment, it’ll dawn on you that a particular BC relates to the airgun being used, almost as much as it does to the pellet. Your rifle may only be able to launch the .25-caliber JSB Exact King out the muzzle at 760 f.p.s. At that speed, the BC of the pellet might be 0.033 (these are not the actual numbers, but they’re very close). By the time the pellet has gone 25 yards from the rifle, its velocity has dropped to 635 f.p.s. and the BC is down to 0.030.

BC is an expression of how much velocity a pellet loses in flight
We know that pellets slow down rapidly after leaving the muzzle. Pellets with higher BCs retain their velocities longer than pellets with lower BCs. A pellet with a BC of 0.040 at 900 f.p.s is going to go farther than a pellet with a BC of 0.020 at 900 f.p.s. Both pellets will change their BCs in flight, but the pellet that has the higher BC will never drop below the pellet with the lower BC at the same distance.

Range equals velocity — how to cheat!
I think most shooters know that the velocity of a pellet starts to decrease the moment it leaves the muzzle of the gun. And the BC is a measure of how much velocity a pellet loses in flight. If I want to get higher BCs, I can get them by measuring velocity closer to the muzzle, where the velocity loss will be less than when the pellet has traveled farther. For example, if I were to measure the BC of a pellet by comparing its muzzle velocity to the velocity at 10 meters, the BC would be higher than if I were to compare the muzzle velocity of the same pellet to its velocity at 25 meters.

I can cheat the numbers by measuring velocity loss at a very close range. The pellet that gives me a BC of 0.033 at 25 meters might give me a BC of 0.040 if I measure the velocity loss at just 10 meters. Standards are needed to make sense of these numbers.

Sometimes, people don’t WANT to make sense! Sometimes, people just want to report a high number because the folks reading the numbers think they mean something good.

In that respect, the discussion of BC among those who don’t really understand what it means is not unlike the discussion of muzzle velocity among new airgunners. Some airgun manufacturers proudly advertise their air rifles can achieve 1,300-1,600 f.p.s. People who are new to airgunning think that’s a good thing. We know it isn’t. We know that to achieve such high velocities requires the use of trick pellets no one would ever use in the field because they’re hopelessly inaccurate.

Next time
There’s a whole lot more to this topic. For example, as the velocity of diabolo pellets rises up into the transsonic region, the BC often starts dropping, again. At supersonic speeds, the pellets are very negatively affected.

We’ll also look at the pellet’s shape, for shape is what makes the BC of bullets and pellets different from other BC numbers. Technically, it’s called “form,” but the term shape is clear enough for everyone to understand.

Swaged bullets: Part 2

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1

This is the second report in this series on swaged bullets. My initial purpose for testing these bullets was to see if I could make a swaged bullet that would shoot more accurately than patched round balls in the rifle barrel of my Nelson Lewis combination gun. While testing that gun, I blew out the nipple and had to repair the gun before it would shoot again. Thankfully, that’s all done now; but I decided, instead, to use a Thompson Center muzzleloader in .32 caliber as the testbed for this idea.

When I first tested the swaged bullets at 50 yards, I couldn’t get a shot on the paper; so this past Monday, I shortened the shooting distance to 25 yards, in hopes I would be on paper. Since I’m reporting this now, you know that I was successful.

One thing I thought might be causing a problem was using too much black powder for the swaged bullets, so I selected a 9mm Luger case as the new powder measure. But there were ignition problems, so that wasn’t the right thing to do. I then adjusted the powder measure back to its smallest measure and shot some patched balls as a control group. The first one was a hangfire that was delayed about 100-200 miliseconds. It sounded like I’d shot a flintlock with a slow lock time. But the second shot with the same load went off perfectly, so I put 4 more downrange after it. This gave a nice group that measured 1.504binches between centers. That’s not great for only 25 yards, but at least the group seemed to be centered on the bull, if a little low.

swaged bullet test 25 yards patched ball
Five patched balls went into 1.504 inches at 25 yards. The 6th shot that landed low was a bad hangfire.

I was exhausting a supply of 3F Goex powder that was at least 30 years old. I’d received it as a gift about 12 years ago, and I think the giver said it was about 20 years old then. So, black powder does hold up over time when properly stored.

One thing I did with the patched bullets was quit cleaning the bore between shots. I used a patch lubricated with saliva, which is recognized as the most accurate round ball lubricant. To do that, I put the patch into my mouth as I began the loading process; then it was wet when I laid it across the muzzle about 30 seconds later. You can only use spit patches if you’re shooting right away; because if the saliva dries, it won’t do anything. Plus, you can rust the bore where it sat. But after 6 rounds had been fired, the bore was still clean enough that I could seat the ball flush with the muzzle with thumb pressure. That told me the bore was not getting any dirtier as the shot count increased. With real black powder, the bore gets dirty on the first shot.

Then it was time for the swaged bullets. The bullets I swaged from .310 lead balls proved too small for success. They missed the target altogether. Then I switched to bullets swaged from .350 lead balls. These seemed perfect and went to the same point of aim as the patched balls. After 4 shots, I thought I had a winner; but shot 5 went almost 6 inches higher, opening the group to 6.25 inches. The first 4 shots measured 1.816 inches between centers — not that much bigger than the patched ball group.

swaged bullet test 25 small bullets with larger bullets
The larger bullet on the left was swaged from a .350 ball. The smaller one came from a .310 ball and didn’t shoot very well.

swaged bullet test 25 yards swaged bullet target1
The swaged bullets did okay until the last shot (upper right). The bore was getting too dirty to shoot well. Notice that at least 2 bullets hit the paper sideways.

This target held a clue to what was happening. Two of the 5 shots appear to have struck the paper sideways, indicating they’re tumbling in flight. Because the bullets are swaged into cylinders rather than spheres, this is very easy to see. Instead of round holes, you get rectangles. Obviously, these bullets aren’t stable in flight, which means they probably aren’t engaging the rifling. Either that or the rifle’s twist rate, which I believe is 1:48″, is too slow.

Some of the holes are perfectly round, however. This either means they were either tumbling and happened to strike the paper point-on, or they were actually stable and for some reason the other bullets weren’t. More work has to be done to sort this out. But let’s now look at the next discovery.

I told you I wasn’t cleaning the bore between shots this time. Well, that came back to bite me. The swaged bullet that had previously slid down the barrel easily was now just entering the bore and staying put. That’s the unmistakable evidence that powder residue is building up on the walls of the bore.

And the next 5 shots on a different target tell the story. Only 4 landed on the target paper and 2 of those went through sideways. The 5th shot landed below the target paper on the paper backer I was using for just this reason.

swaged bullet test 25 yards swaged bullet target2
On the final target, only 4 or 5 bullets hit the target paper. Two of them hit sideways. The 5th shot landed low, off the paper.

That target marked the end of this day at the range. In all, I shot about 25 rounds in about 45 minutes, which is moving right along for a muzzleloader. I tested two weights of swaged bullets with 2 different powder charges and determined that the heavier charge and heavier bullet were both needed. In fact, the next time I test this bullet, I’ll use an even heavier powder charge and try a heavier swaged bullet, to boot.

For the record, I weighed the powder from the measure and discovered it weighed 19.4 grains. This is a light load for a .32-caliber muzzleloader.

I figure the heavier powder charge will help swell the base of the bullet better to grab the rifling, and maybe the heavier bullet will add a little more resistance to help that along. I also plan to clean the bore after each shot, as I now know these swaged bullets require it.

There’s a whole lot more to explore with swaged bullets, but I’ll keep working with this swage set until I know what I’m doing.

Swaged bullets: Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

This is the start of a long exploration into the use of swaged bullets in both firearms and airguns. I told blog reader Robert of Arcade 2 days ago that I was about to start this one because he was talking about wanting to use the larger smallbore calibers (.22 and .25 calibers) and smaller big bore calibers (.257 and .308) to hunt larger game. But to do that, we need bullets (and pellets) that are accurate.

This report has been nearly one entire year in development, but you’re just hearing about it for the first time today. It all began with my Nelson Lewis combination gun that I have written about many times. Back in the first part of that report, I showed you some original bullet swages that came with the gun. The problem I have with these swages is their design. The bullet is swaged into the die, but then has to be tapped back out of that one-piece die, which is very inconvenient. It would be easier to get out if the die had a separate nose punch that could be taken off the die and the bullet tapped on through.

Nelson Lewis gun swaging dies
These dies came with the Nelson Lewis combination gun I acquired.

Last year at the Roanoke Airgun Expo, I saw that airgunner Mike Reames was making swages for some of his big bore CO2 guns, and people were using them with great success. I talked to Mike at some length about these swages and decided that I wanted to try a swaged bullet in my Nelson Lewis gun. But I conducted a proof of concept test with the rifle — to see if I got the bullet size correct . Unfortunately, I shot what proved to be an overload in the gun. It was a 250-grain .379-caliber bullet, where the weight of the round ball I usually shoot is just 80 grains. The pressure created by the heavy bullet blew the percussion cap nipple off the rifle, and I had to get it repaired. That shut down the experiment for a long time.

Earlier this year, I was at the range with my Thompson Center .32 muzzleloader, and it struck me that I could use this rifle as a testbed for the Nelson Lewis gun. Get the Thompson Center rifle working with swaged bullets, then transfer that experience to the Nelson Lewis gun.

I know the barrel diameter of this rifle quite well, so I again started talking to Mike about a swage set. What I was after was a bullet that would slide over the tops of the lands of the rifling and easily slip into the bore. I reckoned that the force of the exploding black powder would expand the base to both seal it against gas loss and also take the rifling. The bullet I want to make is like a Minie ball that’s swaged instead of cast. If this is of interest to you, email Mike for more info.

What is swaging?
Swaging means to form something in a die by pressure alone. It sounds high-falutin’ but it’s as simple as hammering a nail. And it doesn’t take as much force to swage a small caliber bullet as it does to hammer a small, common 6-penny nail.

My swage set arrived and consists of 4 pieces: nose punch, die body, spacer and swage punch…which works on the other end of the bullet. I asked Mike for a swage to make bullets that measure 0.316 inches on the outside, and the two samples he sent with the swage set measure exactly that size. I was now in business to make swaged bullets!

Bullet swage set
Here are the 4 parts that came with my swage set. From the left, they are the swage die, swage punch, nose punch that goes in the small end of the swage die and the spacer.

bullet swage together
The swage is put together as it is used. I left out the spacer because I don’t use it. I control the swage by controlling the force of the one hammer blow used to make the bullet. The results turn out very uniform that way.

I started by swaging some of the 0.310-inch round balls I’ve been shooting as patched balls in the rifle. The rifle is .32 caliber and the lands are about 0.316 to 0.317 inches apart. The round balls weigh only 45 grains, so the bullet they make is very short. The swage puts a concave hollow into the base of the bullet, which helps the lead base expand when the black powder explodes. The nose is slightly rounded but still has a sharp shoulder to cut a nice hole on paper.

swaging .310 balls
The .310 lead balls in the center were put into the swage die, which was resting on the nose punch. Then, the swage punch was inserted in the die and struck one time. The strike was not as hard as hammering a common nail, yet produced uniform bullets. At the top and bottom, they’re standing up. The right one is laying on its side, and on the left one is standing on its nose to show all parts of the finished bullet.

Because I control the weight of the bullet I make by what I put into the swage, I also swaged some .32-caliber lead bullets that weigh 88 grains. They make a much longer bullet that may be more useful for hunting game up to the size of javelina and coyote. The smaller bullets would be okay for squirrels and up to turkeys. Of course, this all comes down to how accurate these bullets are, so I’ll need a good day on the range to find that out. I’m looking for faster, easier loading than patched balls and better accuracy. That’s hoping for a lot, but that’s what this is all about.

swaging 88-grain bullets
The .32-caliber lead bullet (bottom center) was swaged into these three bullets. At the right, the bullet is laying down. On top, the bullet is standing up. On the left, the bullet is standing on its nose.

Why swage a perfectly good lead bullet?
Looking at the last picture you have to ask why I would bother to swage a perfectly good lead bullet like that. Why not just shoot it as it is? Well, the answer is that it’s not a good bullet for the rifle I’m shooting. It has a body diameter of 0.314 inches, which is too small for the bore. The swage enlarges it to 0.316 inches. The finished bullet looks just as long as the one that was unswaged. The concave base of the swaged bullet is where the lead came from to make the cylindrical bullet longer.

I actually went to the range last week for the first test, but I’d used the swage die backwards and got bullets that are far too large for the gun. The swage die is made like a funnel, where fat bullets enter the top and 0.316-inch bullets come out the bottom. That is, if you use it the right way. Since I turned the swaging die around, what I got turned out to be bullets that are far too big for the bore of the rifle.

Swaging mistake
This is what happens when you swage the bullet in the wrong end of the die. The entrance to the die is shaped like a funnel to admit slightly larger chunks of lead to be swaged into smaller bullets. So, the bullet is tapered like this and far too large to enter the bore.

I emailed Mike, telling him I got the dimensions wrong and we started planning what to do about it. That’s when I looked closer at the bullets I’d made and discovered my mistake. I quickly swaged a couple more bullets with the die in the correct direction, and they all turned out exactly 0.316 inches in diameter. Mike was glad, I was happy and I had yet another story to share of how not to do something. The good news is that I can run all the big bullets through the die a second time, and they’ll come out right.

The bullets made the right way will slide down the clean barrel of my muzzleloader in about a second. Right now that seems good to me, but it’ll take a successful range test to know if I’m right.

How difficult is it to swage a bullet?
If you can hammer a nail, you can swage a lead bullet with a die set like this. This is the way accurate rifle bullets have been made for more than 150 years, and it’s dirt-simple. There are no copper jackets to swage the lead cores into, so I’m not talking about a process that requires hundreds of dollars worth of dies and a special press. All you need is a hammer and some lead of the appropriate size. If you wanted to make a .22 pellet by swaging, for example, you could use a 15.43-grain Gamo round lead ball. The weight would be right for a .22 pellet as would the diameter of the ball. What you would be doing is changing the shape of the projectile from spherical to an elongated cylinder.

What you cannot do is use more than one piece of lead to make a bullet. If you do, the pieces will all conform to each other inside the die and fall apart the moment they are out. So, forget any ideas of adding pieces of lead to increase bullet weight.

Mike will make a set like the one seen here for $85. If you aren’t a machinist, this is well worth the price.

The best bullet
Every caliber bullet has a range of weights that will work. Too little lead, and the bullet is shorter than it is wide and subject to be unstable. Too much lead, and it becomes too long — again, subject to being unstable. The faster it’s driven (velocity), the faster it spins (rifling twist rate), which stabilizes longer bullets (to a point). Part of the test I’m doing is to determine what length bullet works best in my rifle. Since length also means weight, we talk about a certain caliber bullet by its weight more often than its length.

Of course, accuracy means a lot in what I’m doing. I’ll be looking for the most accurate bullet I can make. I may have to balance the bullet weight against the powder charge, for reasons of stability explained above.

The goal
I’m doing this to see if there’s any future to it. If there is, then I want to make an accurate bullet for the Nelson Lewis combination gun. That was always the goal. But now that I’ve listened to Robert from Arcade, I think this needs to be tried for airguns, as well. I’m thinking a very powerful airgun and a pellet/bullet that I can make myself.

Rifling twist-rate primer: Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

Recently, we have had a number of questions about rifling twist rates that were attached to the twist-rate report. These questions are extremely important to the understanding of how bullets and pellets are stabilized, so I’m starting a tutorial on rifling twists today. I’ll keep adding sections as I see the need to explain more about the topic.

Today, I want to lay a basic foundation of what the rifling twist rate does. Blog reader Feinwerk asked if centerfire rifles (he said higher-power firearm rifles) had different twist rates than rimfire rifles, and the answer is yes. I’ll get to that, but let me start at a time when things were much simpler.

Early firearms shot multiple projectiles, similar to today’s shotguns that shoot birdshot and buckshot, but much cruder. It wasn’t long before people started experimenting with single projectiles. They found that single projectiles retained more of their initial energy than many smaller projectiles, so they did more damage when they connected with a target. The problem was getting them to connect.

After much experimentation, people discovered that spherical projectiles were the best for firearms. They flew the straightest because they didn’t have the irregular surfaces that created low-pressure zones to guide the bullet astray.

Then, rifling was discovered. Straight rifling (straight lands running parallel to the axis of the bore) was first used as a means of holding all the unburned gunpowder residue, of which there was much. That allowed the gun to be fired more times before cleaning. And, at some point, someone cut the grooves in a spiral — to make them longer to hold even more residue? We’ll never know for sure.

Once people saw how much straighter a spinning ball flew compared to one that was not spun intentionally, the race was on. For hundreds of years, the spinning round ball was the only bullet that was known. It reached its zenith as the patched ball used in the American rifle we know as the Kentucky — where the rifling doesn’t even engrave the lead ball, but spins it by spinning a cloth or leather patch that holds the ball tight while it’s inside the barrel. The ball gets very little distortion from the barrel — although there is a pattern around its circumference where the rifling pressed against the patched ball.

When the patched ball exits the muzzle, the patch falls away and only the bullet travels on to the target. Accuracy increased with this system, and the loading time dropped because the shooter didn’t have to engrave the lead bullet with the rifling when he loaded the bullet/ball.

The conical bullet
Things never stand still, though, and after the patched ball came into general use shooters began experimenting with bullets that were not balls, but rather longer cylinders of lead. These were the first conical bullets.

ball and conical bullet
Although the round ball is very close to the same diameter as the conical bullet, it takes a lot more spin to stabilize the longer, heavier conical bullet.

A ball doesn’t need to spin very fast to be stable because its surface is smooth and regular. A conical bullet, on the other hand, is irregular — being longer than it is wide. Instead of a ball, it’s more like a spinning top that can balance only on its point as long as it spins fast enough. The longer the bullet, the faster it has to spin to remain pointed forward in flight. This attitude is called stability. If the bullet isn’t spun fast enough to remain point-forward, it’ll wobble like a top slowing down; and the varying air pressure that’s created will quickly cause it to tumble in flight. When that happens, the bullet will stray off its straight path.

Twist rate
This is when barrel makers began to be interested in the twist rates of their rifling. Prior to this time, they simply rifled the barrel with whatever twist rate their machinery supported. It’s a fact that the Hawken brothers rifled all their plains rifles with a 1:48″ twist, regardless of what caliber they happened to be.

With conicals, though, the twist rate does matter. Too slow and the bullet tumbles. Too fast and — well, less is known about what happens when the twist rate is too fast; but in my experience, you’re never able to get the same accuracy that you can when the twist rate is just right. A rifle that puts 10 shots into a half-inch with the right twist rate and bullet may put 10 of a different bullet that’s both lighter and shorter (and therefore both moving and spinning faster) into 1.5 inches.

The length of the barrel does not change the twist rate, nor its effect on the bullet — at least not directly. But a longer barrel sometimes does increase velocity. This is always true when black powder is used and can also be true when slower-burning smokeless powders are used.

A bullet that exits the bore of a barrel (of any length) with a 1:12″ twist rate and is traveling 1,200 f.p.s. is spinning at the rate of 1,200 revolutions per second (RPS). Speed that bullet up to 2,400 f.p.s. as it leaves the muzzle, and you increase the bullet’s spin to 2,400 RPS.

If a longer barrel causes an increase in muzzle velocity, it also causes an increase in the rotation rate of the bullet once it leaves the barrel. It does not change the barrel’s twist rate; but because the bullet is going faster; it’s also spinning faster. Reloaders take that into account when they load their cartridges. It’s possible to drive certain bullets too fast or too slow, resulting in less accuracy. Reloading is about finding a balance between the bullet and the velocity at which you launch it.

The M16
The most public and classic case of twist rates and their effects was the launch of the M16 rifle to the U.S. military. It addresses the specific question that Feinwerk asked. The early developers of the 5.56mm cartridge selected a twist rate of 1:14″ because the bullet was barely stable and would tumble and destroy flesh fast when it impacted a body. But they were focused only on the cartridge’s use in Vietnam — a conflict that was mostly conducted at short range and in very warm weather. The 1:14″ twist rate was too slow to stabilize the bullet properly beyond about 250 yards or in very cold weather. It worked great for a 40-grain .224-caliber bullet moving 4,000 f.p.s. from a .220 Swift, but was horrible when used with a 52-grain .224-caliber bullet moving 3,200 f.p.s from an M16.

Don’t confuse the caliber size in inches (.224″) with the name of the cartridge. Both the .220 Swift cartridge and the 5.56mm cartridge (M16) use the same .224″ bullets.

The twist rate for the M16 was increased to 1:12 inches, which worked better, but in time even that rate was discovered to be too slow to do everything the military wanted. Today, the twist rate for an M16 variant rifle runs anywhere from 1:7″ to 1:10″…depending on the specific model of gun, when it was made, which service owns it and what kind of ammunition it’s expected to shoot.

And the answer, Feinwerk, is yes…the twist rate of centerfire rifles does vary by caliber, by the bullets used and the velocities at which they’re driven.

This first twist-rate primer report was written at a very high level. I don’t know whether or not it addresses everything you wanted to know, so I’ll read your comments with interest. If we need to go into greater detail, that’s always possible. Otherwise, I’ll remain at this overview level in the next report.

What about solid “pellets?” Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

The most refreshing thing about this blog is that we keep getting new readers, while retaining a large percentage of our long-time readers. That allows me the occasional opportunity to share an inside story with several hundred of my closest friends. Today is such an occasion.

We got this comment yesterday morning from reader Jp:

BB, got another question: You ever heard of using a solid pellet in an airgun. A bullet, I guess would be the correct term. Considering an airgun tends to shoot like lower velocity black powder (usually subsonic, I assume), maybe use something like a Minnie-ball shot. Know anything about this, how it works, how it doesn’t work, is it worthwhile or even a good idea? Jp

From his remarks, it sounds like Jp may have been a blog reader for some time. And he asks a question that I’ve heard before — not always from the consumer side of the sales counter. Many manufacturers have ventured into the realm of solid pellets without knowing what they’re doing or the ramifications of using such technology in an airgun. I would like to address this issue in some depth today.

A solid pellet is exactly what Jp says — it’s a bullet. It does not have the stabilizing feature of high aerodynamic drag, so all its stabilization must rely on the rifling-induced spin. From tests we did with a smoothbore pellet gun, we know that aerodynamic drag does cause a pellet to fly true for at least the first part of its flight. See the results I got at 10 meters with the Diana model 25 smoothbore.

But that’s not a deal-killer because we also know that a solid bullet (and that’s what a solid pellet really is) can be accurate from spin, alone. I’ve gotten sub-one-inch 10-shot groups from my Winder musket shooting standard-speed .22 shorts at 50 yards, and that rifle has a twist rate of 1:22 inches. Even when the 29-grain lead bullet exits the bore at 1,000 f.p.s. (or less because the Winder has a 28″ barrel that cuts velocity), it can still be accurate from just the spin. We know that an air rifle twist rate is really 1:16 inches, which is faster than the 1:22 inches that’s the standard twist rate for the .22 short cartridge (actually, the rate varies by manufacturer, from 1:20 to 1:22 inches).

Winder musket

The Winchester Winder musket shoots a .22 short bullet of 29 grains weight at less than 1,000 f.p.s., yet it’s very accurate at 50 yards.

If a powerful air rifle can fire a solid “pellet” weighing about 30 grains at 1,000 f.p.s., it should be accurate. Right? I mean, wouldn’t that be what we’ve all been looking for: An air rifle that fires with the force of a .22 rimfire. This is the thinking that certain pellet manufacturers have undertaken in recent years when they got their great ideas to make solid pellets. Yet, I’ll bet a dollar that NONE of those pellet designers have ever shot a muzzleloading rifle.

But you readers have watched me shoot plenty of muzzleloaders. I guess the Nelson Lewis combination gun is the one you remember the best. Know what you have to do with a muzzleloader? You have to pound the bullet into the rifling to get it into the barrel — that’s what. For that, you use a tool called a short-starter. Every muzzleloading guy knows what that is.

Nelson Lewis combination gun short starter
This is me pushing a bullet into the muzzle of the Nelson Lewis combination gun’s rifle barrel with a short starter. They make it with a wide ball end so you can put some force behind it! And this is a patched bullet — not a naked lead bullet that needs to be engraved by the rifling.

Guess what?
If you try to load a solid pellet into a rifled barrel, YOU become the short starter. Or at least your thumb does! Back when a certain solid pellet called a Piledriver first came out, they sent a sample batch to AirForce Airguns, and yours truly had to test them in a Condor to see if they had any merit.

Test them? Heck, I couldn’t even load them! I finally resorted to using a penny on the end of my thumb to push the pellet into the rifling, and even that didn’t work very well. You can sit on the sofa and talk about the benefits of solid pellets all day long, but let’s see how your mind changes when you actually try to load one into a gun!

AirForce Condor air rifle solid pellet in breech
When you try to load a solid pellet like this 30-grain Eley solid into the breech of an air rifle like a Condor, as soon as it contacts the rifling, it stops cold. This is as far as it goes in.

AirForce Condor air rifle solid pellet engraved by rifling
Here’s the proof. Look at the short grooves at the top of the cylindrical section of the pellet, where the rifling has started to engrave the lead. This is the same pellet shown in the photo above.

At this point, the engineers will tell you that the diameter of the pellet’s body is critical. If you can just get it right, these pellets will load. Well, I’ve been testing solid pellets for at least 15 years in dozens of different airguns, and to-date I haven’t seen one that was right. While I was at AirForce, I worked for over a year with the Pelletman (a maker of many kinds of solid pellets), trying to get the dimensions correct…and we never succeeded.

But wait…there’s more
Jp asked a question that I know many other folks have been wondering about. I say that because this subject comes up a lot at the airgun shows. So, I’m not going to leave it here.

I will actually load some of these pellets into a Condor, which is one of the only air rifles powerful enough to shoot them anywhere near the same velocity as a .22 short bullet, and we’ll see just how accurate they are. That’s why today is Part 1.

If you have thoughts, stories or questions, now is the time to speak up.

Nelson Lewis combination gun: Part 4

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3

Nelson Lewis combination gun
Nelson Lewis combination gun is both a rifle and a shotgun.

It’s been a while since I last wrote about this gun. Blog reader Kevin asked if I was going to write anything more and I answered yes, but what I did not tell him or any of you was that in October of last year I blew up the gun.

Blew it up?
That’s not entirely accurate. What happened is the nipple that accepts the percussion cap was blown out of the barrel and right past my face. When it went, it sheared off the hammer lug that connects the exposed hammer to the sear. I never found the nipple, but the hammer was lying on the shooting bench next to the gun. When my shooting buddy, Otho, asked me if I was okay (he was standing behind me, having a premonition that something bad was about to occur), I answered, “NO” for the first time in my life. Usually, guys will say everything is okay right after they’ve sliced off their thumbs with a circular saw, but this event was so startling that I wasn’t really sure what my condition was. “No” just popped out.

What happened?
Okay, get ready to criticize and tell me what I did wrong because I haven’t got a clue. Do you remember me telling you that airgunner Mike Reams can make swages to make conical bullets of almost any caliber? I learned that at the 2012 Roanoke airgun show. And do you remember that I wanted him to make a set for the Nelson Lewis gun? Well, what I did this day on the range was called a “proof of concept” test. I loaded a conical bullet in the rifle — partly to confirm the diameter requirements for Mike and partly just to see if the gain twist rifling really would stabilize a conical. But the only conical bullet I had was a 250-grain lead bullet for my 38-55 Ballard, which coincidently has almost the identical size bore as the Nelson Lewis rifle.

I’d been shooting a patched .375-caliber swaged round ball in the rifle up to this point. That ball weighed 80 grains. So, 250 grains would be heavier — about 3 times heavier. What I did was load a proof load into my 160-year-old gun and shoot it. Nothing wrong there, right?

When the gun fired, it recoiled more than usual (no kidding!), but that wasn’t what I noticed. I noticed a jet of fire about a foot long coming out of the nipple hole that had been so recently vacated. Then there was the verbal exchange between me and Otho, and then he cautiously walked around to my front and looked at my head — mostly to see if it was all there.

I’d been wearing shooting glasses, which I always do whenever I shoot a black powder arm (and after this event, when I shoot anything else, too), so my eyes were fine; but above my right eye was a large patch of black powder that embedded itself in my skin. I looked like the “murdering coward Tom Chaney” from the movie True Grit, who coincidentally had a black powder Henry rifle blow up on him. The powder had to be picked out of the skin with tweezers over the next few weeks and there is still some of it in there today, more than 4 months later. But I was okay.

My Nelson Lewis gun, on the other hand, was broken. And, as far as I know, Nelson Lewis doesn’t work on his guns anymore, having been deceased for the past 135 years or so. What was I going to do?

Otho to the rescue
Now you need to know something about my buddy, Otho. He’s a retired Airframe and Powerplant (A&P) mechanic who has worked on turbine engines and airframes since Vietnam. One of his skills (he has skills — and people like me need to know other people with skills) is welding. And I don’t mean trailer-hitch welding, either. I mean the ability to — well, let me tell you what he once did. His father stored a Gen-1 Colt Single Action Army revolver improperly, and it rusted badly. Rusted as in deep pits all over one side of the gun. So, over the course of a year, Otho spot-welded each and every pit, then worked it down with a file until it was flush with the rest of the metal. When it was perfect, and by perfect I mean perfect, he had the gun re-case-hardened so that today it looks new. All the factory lettering was preserved so you cannot tell that any work was ever done. Or at least I cannot tell, and I know Gen-1 Colt SAAs.

Nelson Lewis combination gun Otho welded gun
Both these Colt revolvers were stored together and rusted equally. Otho welded every rust pit and refinished the Single Action Army on top. This is a master at work!

So, Otho looked at the sheared hammer lug on the Nelson Lewis gun and says he thinks he can fix it. He thinks he can weld the hammer lug back up and file it to fit the hammer. This news sounds wonderful, coming as it does on the heels of the gun’s destruction. Let me show you what is involved.

Nelson Lewis combination gun nipple out
The nipple is gone. All the threads are, too.

Nelson Lewis combination gun hammer sheared off
The hammer was sheared off at the lock plate. The other end of that square lug is the rifle’s sear.

Nelson Lewis combination gun hammer front
The hammer was sheared off the lock as neatly as if it had been properly removed.

Nelson Lewis combination gun hammer back
The flip side of the hammer shows the lug that was sheared.

Nelson Lewis combination gun lock interior
See the part with the leg sticking out? That’s the sear. It also has the lug that the hammer used to be connected to — or at least it is supposed to.

I disassembled the lock and looked at the sear carefully. Surely, it was made in two pieces because how did Lewis put a square lug on a complex sear otherwise? You know what? He cast the part in one piece. Out of steel. In 1850! They wouldn’t have automobiles for half a century and here was this gunsmith in upstate New York making complex parts from cast steel! I thought Bill Ruger invented the casting of gun parts. (Just kidding. Please don’t hit me with comments. I am aware that the lost wax casting process is very ancient.) But seriously, did you know that gunsmiths in 1850 were casting parts from steel? That’s not the paradigm I’ve been given to believe.

And one thing was certain because of how the part was initially produced. It would either have to be welded or made entirely new. Otho’s plan now sounded very good.

In November, I gave him the lock pieces and he began to study them. His task wasn’t just to weld the lug, but also to maintain the correct orientation so the hammer would fire a percussion cap again. And that brought up the other thing — there was no nipple for the cap. It was blown off the gun and never found. And the threads in the hole where it was were completely stripped. Otho had an idea about that. Use a Heli-Coil. When I balked, he told me that a Heli-Coil is approved by the FAA for threading stripped holes. And the FAA is about as anal as they can be when it comes to parts’ integrity and safety. So, I guessed it was okay.

He began welding small amounts at a time. Welding and welding, and then filing when he got close to the right dimensions. Then it was weld and file, weld and file. This went on until January. I think he finished the job while I was at the SHOT Show. Then he told me about his worry. He had been worried that the sear metal might vaporize as he welded, but that hadn’t happened. So the steel was good. Now he was concerned that all the heat from welding had taken all the hardness out of the part.

He took the part to a knife-maker friend of ours to have it Rockwell tested. But the part was too odd-shaped and small to fit in this guy’s tester. So, he drew a file across it and made a guess what kind of steel it was based on the date of manufacture and how it took the file. Then, he hardened it in his kiln until it was hard as glass. Next, Otho did a complex series of tempering heats that drew the hardness down to approximately Rockwell 38, which the knife-maker guessed was the hardness of the original part. Do you think this is too much guesswork? How do you think Nelson Lewis did it in 1850? He heated it on his forge until it glowed brightly enough, then quenched it in whatever oil he had (possibly sperm whale?), then he drew the temper the same way.

Nelson Lewis combination gun sear restored
The hammer lug (the square projection standing up in this picture) has been restored to the sear. No, the lug isn’t perfectly square. It’s shaped exactly like the hole in the hammer. The hole for the hammer screw was even drilled off-center and threaded exactly like the original.

The proof of the pudding
Otho installed the Heli-Coil and a new nipple I gave him, then the both of us reassembled the rifle. He was very concerned about the hammer, so I test-fired just a percussion cap in my garage and everything was fine.

I went to the range to test the rifle with a full charge of powder and a correct bullet. First, I shot off another cap, to clear the path in the nipple. Then, I loaded about 20 grains of powder and tamped just a wad on top. That was fired okay, so now it was time to load the rifle for real.

I loaded the rifle the same way I’d loaded it before — with a patched round ball ahead of about 20 grains of 3F black powder. I tied a 10-foot cord to the trigger and carefully cocked the hammer. I pulled the trigger with the rifle sitting in the rest and it fired without incident.

Nelson Lewis combination gun with lanyard
This shot was posed. I was 3 feet farther back when I fired the gun for real.

Nelson Lewis combination gun shooting off bench
Once I knew the gun was safe, I shot it like I had before the accident.

Once the gun passed the test and I knew it was safe to shoot again, I settled down and shot a quick 5-shot group at 50 yards. It shot to the same point as before the accident and grouped about the same.

Nelson Lewis combination gun shooting 50 yard group
Five shots at 50 yards made this group. It’s in the same place and the same size as before.

How does the gun look now?
I’m sure you’re curious how the gun looks after this trauma. The fact is, apart from a small dent in the top of the pistol grip where the hammer spur hit the wood, you can’t tell anything ever happened. I thank the Lord for my safety, and I thank Otho for being so skilled. I’m so fortunate to have my gun back and whole again.

No moral
There is no moral to this story. And I hope you readers are all smart enough to not need to learn anything from my misfortune.

I will continue to shoot the rifle, but not a lot. I think, given the circumstances, this rifle has done enough for me. It deserves a rest and, except for an occasional day or two, that’s what I intend to give it.

Benjamin Rogue ePCP: Part 5

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3
Part 4

Benjamin Rogue epcp big bore air rifle
The new Rogue is simpler, more tractable.

Think of this report as a bonus. I thought I was finished with the Rogue after Part 4, but then Seth Rowland — the man who organizes the Malvern, AR, airgun show and also provides big bore airgunners with swaged and cast lead bullets — contacted me, saying that he had been following the series. He told me he had a couple different bullet designs, some that he swages and can control the weight and length of the bullet. He wondered if I wanted to test the rifle with some more bullets — this time from a source other than Crosman/Benjamin. He had no idea whether any of the bullets would work in the rifle, but he did know they were large enough to fit the bore well.

I thought, what the heck — let’s give them a try. I contacted Crosman to get an extension to the loan of the new Rogue. Since this gives me one more day at the range with the rifle, who am I to complain?

Seth sent me 5 bullets in all. They range from 89 grains to 137 grain, so the spectrum is covered pretty well. You may remember that I found the Rogue to shoot best with lighter-weight bullets, which is why Seth sent me these particular ones.

Benjamin Rogue ePCP big bore precharged pneumatic air rifle bullets
From the left, we have an 89-grain swaged bullet, 119-grain swaged bullet, 128-grain cast bullet, 130-grain cast bullet and a 137-grain swaged bullet.

At the range
The day was perfect. The wind was a light breeze that caused no problems at the 50-yard range. I took each bullet in succession, starting with the lightest weight and progressing to the heaviest. Each bullet shot a 5-shot group at 50 yards. The electronic valve setting was on Light for the bullet and Medium for the power. I figured that if any bullets showed promise, I could return and test them on High power later.

The 89-grain bullet had only fair accuracy and strung its shots vertically in a group measuring just under 4 inches. It was too early in the test to know very much, so I moved on to the 119-grain swaged bullet. It opened up to just over 5 inches, telling me this also was not a bullet for the Rogue. Since it was also swaged, I wondered if that was causing some kind of problem.

The next bullet was the 128-grain cast bullet. Five of those landed in 1.483 inches, looking very nice, indeed. That’s certainly minute-of-coyote or fox at 50 yards…and on out to, perhaps, 75 yards. The cast bullet looks like a design for either a black powder cartridge or a pistol. It was the best group I got so far.

Benjamin Rogue epcp big bore air rifle 128 grain cast bullet Medium power
Five shots with the 128-grain cast bullet on Medium power produced this group, which is under 1.5 inches.

Next came the 130-grain cast lead bullet, and it didn’t even land on the target paper. Since I back my targets with a 2-foot by 4-foot target paper to catch strays like this, and since I failed to catch this bullet anywhere, I stopped trying after three shots. Let’s call the 130-grain bullet a non-starter for the Rogue.

The last bullet was a 137-grain swaged design that also failed to make a hole on the large backer paper after 3 shots. It was out, as well.

So far
To this point, it looks like the 128-grain cast lead bullet is the one to spend time with. I chronographed it and found it averaged 699 f.p.s. on Medium power (138.91 foot-pounds) and 731 f.p.s. on High power (151.91 foot-pounds). On Medium power with a fresh 3,000 psi fill, the gun’s status panel tells me there are 11 shots at the beginning. But the status panel number of shots that remain decreases faster than the actual number of shots. Although it says there are 11 shots, there are really 6 or 7 shots before it’s time to fill again.

On High power, the gun starts out with 3 shots on the panel — but I found that I got only 2 shots before the gun wanted to be refilled. A third shot was possible, and I took one just to see where the bullet went. It stayed within the group, though on High power the group is larger than on Medium.

Benjamin Rugue epcp big bore air rifle 128 grain cast bullet High power
Five 128-grain bullets on High power opened up to 2.847 inches. The shot at the right is after a refill of air.

What do we know?
First, we know that cast bullets with grease grooves seem to shoot better in our Rogue than swaged bullets. At least, there’s an inclination in that direction.

Next, we know that the 128-grain bullet did best in this rifle. If further testing was to be done, that’s the bullet I would concentrate on. I went back and reviewed the performance with all the other bullets that were tested in the past, and this one looks quite similar to the Benjamin Pursuit 127-grain flat-nosed bullet. What that means is that it’s possible to cast your own bullets or to buy them from a source that casts them, as they’re going to perform similarly to the best bullets in this rifle. Both these bullets out-shot the 145-grain Nosler Ballistic Tips that are also good in the Rogue.

We also know that shooting on Medium power conserves air longer than High power, and the slight loss of velocity is inconsequential. Of course, I’d like to play with this bullet even more, shooting it with the control panel set to Heavy weight and shooting it on Discharge, as well as directly controlling the valve dwell time. From just what we have seen in today’s test, I would say this is a bullet to beat.

Remember — this was a test of unknown bullets to see if any were worth testing further. If I owned a Rogue, I would stock up on this 128-grain bullet and play with it more because I think this may be the best overall design for the rifle.

Thanks to Seth Rowland (sethrowland@att.net) for providing these bullets to test. He makes other calibers and will work with you to find the best bullet for your rifle.

Bottom line for the Rogue
The Rogue has its detractors — those who feel that it’s to advanced and expensive to be practical in the field. But those people disregard the fact that this rifle shoots as well as almost all other big bores of quality.

All I’ve done in this 5-part test is show you how it performs. The rest is up to you.

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