What about choked barrels?
This report covers:
- In the past
- What is a choke?
- Shotgun chokes
- Chokes are more than a century old
- Lothar Walther chokes their barrels, too
- How to tell if you have a choke
- Back to 2022
- Diabolo pellets
- Modern rifle barrels
- So — choke or not?
This past Tuesday in Part 5 of the Seneca Dragonfly Mark 2 report a reader named Bill, asked this question:
Does the DF MK2 have a choked barrel?”
I answered him with this:
“I don’t know. I rather doubt it because that is usually an extra step in the barrel-making process and has been shown to be of limited or no value when it comes to accuracy.”
Then Bill came back and said
I’ve been led to believe a choked barrel to be more accurate than non-choked
but I’ve only just started down this air gun path, so much to learn.
I assume there are probably no newly manufactured multi-pumps with a choked barrel?
I look forward to more of your findings on the Dragonfly Mk2, looks
very impressive so far.”
To which I responded:
“I may have been one to lead you in that direction. I believe that a report on choked barrels is in order.”
In the past
I don’t want to confuse you, but BB has written some things about choked barrels in the past that may not be completely accurate. That’s why I apologized to Bill. Remember, guys, I’m learning right along with you.
In June of 2005, just 4 months after this blog started, I said the following.
Some airgun chat forums are currently buzzing with discussions about choked rifle barrels and what they can or cannot do. As usual, there are a few knowledgeable people and a much larger crowd of kibitzers with nothing to say – and saying it very loudly.
What is a choke?
A choked barrel refers to a reduction in the bore dimensions at the muzzle of the gun. The purpose for this reduction, according to pellet makers at Handler & Naterman (H&N), is to size all pellets just before they leave the gun. It ensures uniformity.
Shotgun barrels are choked to achieve different densities of shot at different distances from the muzzle. Today I’m just talking about rifle barrel chokes.
Rifle chokes are more than a century old
Let’s examine history to see if chokes really work. First we learn that Harry Pope, the acknowledged Stradavari of rifle barrel makers, almost always choked his barrels. Most of the guns he made (and ALL of the most accurate ones) were muzzleloaders, and you might wonder how a choked muzzle can benefit a bullet that is rammed through it during the loading process. Wouldn’t that squeeze it too small?
Well, when the powder charge ignites, burning gasses smack the base of the bullet hard, smashing it out fatter until it hugs every crevice of the bore. When it gets to the muzzle, the choke sizes it down once more just before it leaves the gun. Pope’s barrels set every world record in their day; a century later, they’re still regarded as some of the finest barrels ever made.
Lothar Walther chokes their barrels, too
A second endorsement comes from Lothar Walther, the German company that is well-known for making fine airgun barrels. They can supply their barrels with or without a choke, but their choked barrels out-shoot their unchoked barrels by a significant margin. They tell that to anyone who does business with them.
Now, a word from the school of hard knocks…
There are the incidents of hundreds of airgun tinkerers who have cut off the ends of their barrels for one reason or another. They nearly always suffer an accuracy loss that they can never recover. They will tell you the reason the shorter barrels don’t shoot as accurately is because of the new crown (the shape and uniformity of the muzzle), but the truth is that no amount of re-crowning will ever get those barrels to shoot again. The one instance where cutting off the end of a barrel improves accuracy is when the muzzle has been ruined by improper cleaning that has worn away the rifling.
How to tell if you have a choke
Use a cleaning rod to push a pellet through your barrel from the breech to the muzzle. You’ll feel resistance at about 1.5-inches to 2-inches from the muzzle on a deliberately choked barrel.
Pope lapped in his chokes during the polishing process. Modern barrel makers squeeze the bore down mechanically – a process known as swaging. On many springers, the act of swaging in the front sight dovetails on the outside of the barrel also reduces the bore at the muzzle. It isn’t a formal choke, per se, but it works just the same.
The choke discussion is a topic that has fueled conversations for more than a century, and it isn’t going to end here. An interesting book on the topic of accurate barrels is The Story of Pope’s Barrels by Ray M. Smith.
Back to 2022
Okay, over the 17 years this blog has been running, old BB has had occasion to learn a few things. Back in 2018 when I went to Sig to see the new ASP20 air rifle I asked them whether it had a choked barrel. Ed Schultz (yes, the same guy who is now back at Crosman) told me the ASP20 barrel was unchoked, and in their experience, it didn’t really need to be choked. When I shot it at Sig and again when I tested it for you in this blog I discovered he was right.
So — does a rifle barrel need to be choked? Sometimes yes, most times no. And get this — if it is an extremely well-made barrel by Harry Pope, it is choked and does need to be. And if it is an extremely cheap barrel from China, choking can help.
Let’s talk about China first. What does a choke do for a cheap barrel? It makes certain that the last part of the barrel to touch the pellet is uniform. If you have ever pushed a pellet through a cheap barrel with a cleaning rod you know there are loose spots and tight spots. A barrel like that doesn’t help accuracy very much. A choke can help a barrel like that.
But what if the barrel is uniform all the way through? Well, for starters, never get rid of that barrel, because it’s a special one. Then you say, “Aren’t all barrels supposed to be uniform all the way through?” Yes, they are supposed to be and no, they usually aren’t.
But we shoot airguns and they have something in their favor that firearm bullets don’t have. They have soft thin skirts that get blown into the rifling when fired. Unless the barrel is really bad, that is a great plus that firearm barrels don’t have.
Harry Pope made barrels for lead bullets. There is a small bit of expansion at the bullet’s base when the powder goes off, but the barrel would have to be uniform all the way through for that to have the desired affect. Pope’s barrels were. Schalk’s barrels were. And a few other legendary barrel makers barrels were uniform all the way through. Pope simple hedged his bet by putting in about a half-thousandth choke at the muzzle end of the barrel.
Modern rifle barrels
How about modern firearm barrels? If they are made for shooting jacketed bullets I doubt you will ever see one that’s intentionally choked. Uniformity through things like barrel lapping is the preferred way of treating such barrels.
However, some .22 rimfire target rifles that shoot lead bullets are intentionally choked. Again, it’s the hedge against non-uniformity in the barrel. With lead bullets a choke will work.
So — choke or not?
This question is like asking which of your children do you love the most. If you have an answer you will never say it. Or you may want a choke just because you have heard they are good. Same, same either way.
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