The importance of the crown

by B.B.Pelletier

This report is going to start a controversy, because it dares to question the things that are currently held dear among airgunners and firearms shooters, alike. Sorry, but here it goes.

What is a crown?
The crown is the end of the barrel, or the place at the muzzle that has the final influence upon the bullet as it transitions to ballistic flight. One popular belief is that if the crown is not perfectly symmetrical, then one side of the pellet or bullet can exit before the other and allow escaping gas to impart a destabilizing effect on the bullet at the beginning of its path to the target. So, crowns have to be perfect, according to the vast majority of shooters.

The other side
But there have been experiments done that show that escaping gasses have zero effect on a bullet in flight. The most well-documented of these were done by Dr. F.W. Mann, who wrote about them in his book The Bullet’s Flight, From Powder to Target. Dr. Mann did numerous experiments until finally he demonstrated that a plank six inches long placed within 1/16 inch of the muzzle blast has absolutely no effect on the accuracy of a bullet.

You see, in Dr. Mann’s day riflemen believed that the muzzle blast had a deleterious effect on the flight of the bullet, and they warned shooters to keep the muzzle clear of any and all obstructions.

The issue
But is what Dr. Mann tested the same as an inaccurate crown? Maybe not. The question seems to be what, exactly, does the crown do?

The end of the rifling and the face of the muzzle bore must be as square as possible to the bore for the crown to be perfect. The reason for this is as I stated earlier — that the base of the bullet/pellet leaves the muzzle at exactly the same point around its circumference, rather than one part coming out before the rest. But there are all kinds of crowns, including some that don’t look like a crown at all.

Let’s look at some crowns now.

The crown of this Ballard target rifle is flat and polished like a mirror. The old-time shooters felt it was easier to see the distribution of the bullet lube — as it made a pattern on the face of the muzzle. There’s almost no break between the bore and the muzzle on this rifle — which is one of the more accurate ones I own. In the 135 years since this rifle was made, there has been no damage to this crown.

This Butler Creek bull barrel for a Ruger 10/22 has a recessed crown that’s similar to the Ballard crown except for the recess. However, on this one, it’s possible to see a tiny break (chamfer) at the muzzle. With the right ammunition, this rifle can hold 10 shots close to one-half inch at 50 yards. The recess supposedly protects the actual crown from inadvertent damage.

No doubt that this crown on an FWB 300 target rifle will look more familiar to most shooters. It’s the traditional rounded or radiused crown with a protected chamfer at the true muzzle. It’s on my most accurate ten-meter target rifle. Doesn’t look so pretty up close, does it?

The crown on this HW55 SF air rifle is similar to the one on the FWB 300, but up close it looks pretty disgusting. The rifle is one of the more accurate 10-meter target rifles I own. So, looks can be deceiving, and a “perfect” crown may not be all that it’s cracked up to be.

Not looking like your typical crown, this Swedish Mauser M1938 crown is a lot like the “redneck” crown job that hobbyists do on their guns. This is on a very accurate rifle. The lighting makes the bore seem to have a shoulder around the inside of the muzzle, but it doesn’t.

The redneck crown
Since the 1960s, there has been a hobbyist approach to crowning a barrel. It consists of a round-headed brass screw and a grinding compound — like automotive valve grinding compound. Chuck the screw in a hand drill and coat the domed screw head with grinding compound. Then, run the drill motor slowly while allowing the axis of the drill to oscillate to avoid making an oval cut. The result will look something like the crown on the Swedish Mauser M1938 shown above.

The crown on a custom barrel for a .17 HM2 rifle. Though brand-new and not even broken in yet, this rifle has already shot a five-shot 50-yard group that measured 3/8 inches across the centers of the widest shots. Note the powder burn pattern around the muzzle. This is the same thing that old-timers analyzed on the mirror surface of the Ballard muzzle when it was bullet lubricant that spread out instead of carbon fouling. This is another deadly accurate rifle that has no noticeable “crown” to the muzzle. The transition is very close to 90 degrees.

The crown on an AirForce Condor is very similar to the recessed target crowns shown before, except that this one has a definite chamfer or break at the muzzle. This rifle shoots half-inch five-shot groups and three-quarter inch 10-shot groups at 50 yards. And, yes, I did notice that it is time to clean this barrel!

So, what’s the verdict?
I’m not sure. That’s where I am on the whole crown issue. The reasoning makes some sense, and I can see why a PCP or a CO2 gun would then need a good crown, but a springer barely has any compressed air exiting the muzzle, so where’s the advantage there?

Don’t say anything about crowns removing burrs at the muzzle, because Dr. Mann did an extensive test in which he screwed blunt-tipped screws into the side of his Pope barrel at the muzzle to see if burrs at the muzzle that deformed bullets affected accuracy. They did not. He set his blunt-tipped screws to plough to the bottom of the grease groove of the exiting bullet, and no change was noticed in its accuracy at 100 yards.

Are crowns placebos?
I’m still undecided on the importance of crowning a barrel. I’ve read what everyone says, which is that the crown is of paramount importance to the accuracy of the barrel, yet I’m not convinced that it is. I’m also not convinced that it isn’t. I just don’t know.

I think there’s something more that has not yet been discussed about crowns and their importance to accuracy, but I’ll be darned if I know what it is. Do shooters shoot better after receiving (or doing) a crown job on a particular barrel? If you read what they write, they seem to. And most shooters believe that the barrel’s crown is of great importance to the performance of the barrel.

I wish I knew for sure, but I don’t.

What would B.B. do? Part 3

by B.B. Pelletier

Part 1
Part 2

I’m on the 50-yard range with my Talon SS.

If you guessed that this was what I was going to write about today, good for you. I certainly left enough clues. And by “clues,” I mean hitting you over the head until you were bloodied by all the obvious references to what I am about to show.

The Talon SS stock DOES NOT have to be modified
But before we get to that, I told you back in Part 1 that I would be showing you things about the .22 caliber AirForce Talon SS that have never been seen before. Here’s one of them now. You know how people are always inventing things to “fix” AirForce airguns because the factory isn’t smart enough to do it right to begin with? Well, I used to stand in their booth at both the SHOT Show and at the NRA Annual Meetings; and whenever someone would come up and complain about how they couldn’t get their head down far enough on the stock of one of these rifles, they didn’t want to run into me! But some of them did, to their misfortune.

When I asked them to demonstrate the problem they shouldered the rifle with the buttplate squarely in their shoulder joint, like they would hold Winchester 1894. But the AirForce rifles are not Winchester 1894s, and they don’t respond to being held like one. If you try to hold one of them that way, the scope doesn’t come up high enough and you have to lean your head way over to the side to see the scope picture. The only time holding like that works is when you’re seated at a bench.

But if you hold it the way I’m going to show you today, you can mount the scope as low as possible and still have plenty of elevation for your sighting eye when shooting in the offhand position. It’s all in how you plant the butt on your shoulder.

Just above your collarbone, there’s a small pocket of meat that will hold the toe of the AirForce buttplate very nicely. If you learn to plant it there instead of holding it like a recoiling deer rifle, the scope then comes up to your eye naturally.

I’m pointing to the pocket above the collarbone where the toe of the buttplate will rest. (I should put a no-nudity clause in my contract!)

This is the proper hold for an AirForce air rifle when shooting off-hand. It’s sitting on the top of my collarbone. Notice that my head is erect and the scope is easily in line with my eye.

“But that’s so unnatural!” comes the complaint from the now-backpedaling shooter.

“What?” I ask in mock amusement. “You never shot a Light Antitank Weapon (LAW) or a Redeye missile?”

The funny thing is — most of them never did. These are the same guys who will try to use the sights on an M3 grease gun and then complain loudly that they don’t work. Of course they don’t! Nobody in their right mind would try to use them to begin with. You want to use sights on an SMG? Get an H&K MP5. The M3 is like a very nasty garden hose, on which, coincidentally, there are also no sights. Yet, somehow, people manage to get the hang of using a hose without taking extension courses or watching a video, and the same can be said for the M3 grease gun. All it takes is some time and enough ammo to waste to find out how the bleeping thing works.

So it is with the AirForce air rifles. When a serious shooter is shown the correct positioning of the butt, he grouses about it for a moment, then proceeds to shoot the lights out of all the targets. After that, there’s no more discussion. That’s one of the tips about these rifles you’ll never see anywhere else. Since I no longer work in the AirForce booth, you’re not in danger of being exposed to my shenanigans if you do go to a show.

How accurate can the Talon SS be?
I have already shown my unclothed body in today’s report, so I think I’ve stepped boldly over the line. Nothing else I say today will damage my reputation any further. So, here it goes. The Talon SS will out-shoot a customized Ruger 10-22 upon which a lot of time, talent and money have been expended. It doesn’t just out-shoot it by a small margin, either. It buries it! There! (Let the letters and emails start to fly!)

Several years ago, I wrote a series of four or five feature articles for Shotgun News about the Ruger 10-22. Each article was 4,500-5,000 words long and had about 20 photos, so they were pretty detailed. The title of the series was, What can you do with a 10-22? The goal I was working toward was to find out how hard it is to obtain a legal silencer and also how a silenced .22 rimfire rifle compares to a quiet air rifle. I haven’t finished that series yet, and perhaps I never will, because the reader reaction seemed to be, “Who cares?”

But while doing the series, I had the opportunity to have my own 10-22 gunsmithed in several important ways. I had the trigger lightened to 1.5 lbs. with a crisp letoff and an adjustable overtravel stop. The barrel was rechambered with a target chamber, which is much tighter than the rifle comes with, and the headspace was made tighter and more precise. I also had a bolt hold-open device installed and the magazine release made simpler to use. Then, I created a custom rifle on that customized action by adding a custom stock and a 20-inch bull barrel from Butler Creek.

The Ruger 10-22 is a very popular rimfire rifle that can be modified in many different ways.

Replace the factory barrel with a 20-inch bull barrel from Butler Creek and drop the whole thing into a custom laminated stock and this is what you get.

I tested the rifle out of the box, the same rifle after modification and the all-out custom rifle with about 100 10-shot 50-yard groups shot by about a dozen different .22 rimfire cartridges. I wanted to see how accurate my factory barrel was, then the same barrel with a target chamber and custom headspacing, then the same rifle with the Butler Creek barrel and the custom stock…and, finally, I conducted a two-gun shootout between my now-$800 custom rifle and a Ruger 10-22 Target model straight from the box.

Ruger also sells the 10-22 in this Target model. It has a hammer-forged barrel and many of the modifications that had to be done to the factory rifle, and the cost is about half of what a custom job costs.

A lot of different ammo was used in the test.

Please bear in mind that I was shooting 10-shot groups — not the five-shot fluff groups that many gun writers get away with today. Well, the absolute best 10-shot 50-yard group of that entire multi-part series was fired by my customized rifle and measures 0.537 inches between centers at 50 yards. To get it, I used Aguila Standard Speed ammunition. And, yes, I bought plenty of the expensive ammo for this test, as well. It simply did not measure up to what the Aguila standard speed rounds could do in the three rifles I was testing.

The best group of the entire 10-22 series was made by Aguila standard speed ammo in my highly customized 10-22. It measures 0.537 inches between centers and is 10 shots at 50 yards.

That group represents the best of dozens of similar groups under the best of conditions. There were many 10-shot groups under seven-tenths of an inch extreme spread and several that were under six-tenths, but none were better than the one mentioned above.

And, now, the Talon SS
But last week, when I sighted-in the Talon SS at the range with 18.1-grain JSB Exact Jumbo Heavy pellets for this report, the sight-in group measured 0.734 inches between centers. It was just the sight-in group that I fired in haste to see where the scope was shooting! I have so many pellet guns that scopes are mounted and dismounted all the time for tests, so practically nothing is ever sighted-in when I begin a test. Six of the ten shots in this hasty group went into a smaller group measuring just 0.275 inches, or just larger than a quarter-inch!

This group was fired at 50 yards as fast as I could shoot, without waiting for the wind gusts to die. The large hole on the right is where six pellets passed through.

I was bucking the wind during sight-in and several of the stray shots were taken when I shot before I should have. I was just anxious to get the rifle sighted-in and didn’t think this first group would amount to anything. After seeing where the center of the group was, I made the appropriate adjustments to the scope and moved the point of impact closer to the point of aim, but still far enough away that I didn’t shoot out the aim point.

This is getting to be a very long report, so I won’t keep the results from you any longer. The best 10-shot group I obtained with my Talon SS shooting JSB heavies measures 0.431 inches between centers and puts the entire Ruger 10-22 test to shame! Yes, the day was perfect; and, yes, I did everything right to get that group, but that was also true for the 10-22s on every one of the 10 range sessions I had with the three different rifles.

The best group of this session and a killer group, to boot! Ten JSB Exact Jumbo 18.1-grain pellets went into a group that measured 0.431 inches between centers.

This may be the best group I’ve ever shot with this air rifle, but I simply don’t know because I don’t keep such records. What I do know is that I can sit down on any calm day and do something very similar. Now that I’ve discovered the best pellet for this rifle, I have even greater confidence in the gun.

I shot two other groups with the Heavy JSBs. They measured 0.476 inches and 0.494 inches, so all three beat the very best my 10-22 custom rifle was able to do.

Then, I tried 14.3-grain Crosman Premier domes. I shot only a single group with them because they measured 0.559 inches for 10 shots at 50 yards. For most air rifles, that would be a screamer for a 10-shot 50-yard group, but not for my SS.

Ten Crosman Premiers went into this group measuring 0.559 inches between centers.

I followed that with the heavy Eun Jin 28.4-grain domes, which produced almost 42 foot-pounds in the velocity test. Again, I shot only one group and it measured 0.935 inches at 50 yards. That’s good, but nothing to write home about. It seems that the 18.1-grain JSB Exact is the pellet of choice for this rifle.

Ten 28.4-grain Eun Jin pellets went into this group, which measures 0.935 inches. While not as tight as the others, this pellet generates almost 42 foot-pounds in this rifle and retains that energy better than any other pellet.

While many of you might be surprised by what this rifle can do, I was not. I’ve grown accustomed to results like this from my long-barrel Talon SS. That’s why I don’t bother to save the targets. I know I can always do it again on any calm day.

So, my statement remains — the AirForce Talon SS out-shot the Ruger 10-22 customized rifle and a factory Target model. And, I shot all of the guns in all of the tests.

One of our readers said in the comments of an earlier part of this report that a CZ 451 American was cheaper in the long run than a Talon SS when all the support equipment gets tossed in. I won’t argue that point until it comes to buying the ammunition. But can the CZ keep up with my Talon SS downrange? Maybe it can. I know CZ makes a great barrel, but there’s still the difficulty of finding the rimfire ammunition that really works well in your particular gun. Having done an exhaustive test with the Rugers, I don’t know if I have the energy to do another one equally as exhaustive. Especially not when I know that all I have to do is pick up my Talon SS with its optional 24-inch barrel and start shooting.

I believe today’s blog is the longest one I’ve written to-date. It had to be this long, because I had to tell you everything at the same time so you could appreciate what I have known for years. I guess I became very accustomed to the high accuracy of AirForce rifles when I tested so many of them years ago. I don’t think about it very often, but we have enough new readers who need to know what I know about these airguns, so it was high time to speak up.

This isn’t the end of our look at the Talon SS. Oh no! This is just the beginning. Now I have a baselined PCP air rifle against which I can test .22 rimfires. I’m looking into such things when shooters make the statement, “I don’t need an air rifle to eliminate pests. My 10-22 with CB caps is just as quiet and just as accurate and whole lot cheaper in the long run.”

What do you think?