By B.B. Pelletier
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.
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 Stadivarius 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″ to 2″ 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.
Does the gamo cfx have a choke?
Matt,
Almost no spring guns have intentional chokes. The Whiscombe is the only one I know that does. The CF-X is not choked.
B.B.
B.B.,
The diablo pellet has a distinct head and skirt. It seems that you wouldn’t want the head making contact all the way down the bore since that would increase friction. It just seems with the head smaller, then the pellet could have a slight angle (yaw?) going down the bore.
Near the end of the barrel, the lands/groves have been “worn” into the skirt. So at bit more of a constriction wouldn’t slow pellet terribly.
QUESTION: Since the head is narrower in diameter than the skirt, is the purpose of the choke to cause the head to line up (center) axially with the bore?
Herb
Herb,
There's not supposed to be any yawing of the pellet in the bore. Although the head is smaller, it's still supposed to be centered & engraved in the rifling. What the choke does is ensure that all pellets emerge from the gun with a uniform diameter because some of them are so small that the choke's the only thing that they contact. It squeezes them all down to the same size.
B.B.
So,theoreticaly an unchoked barrel can be just as accurate if the pellet size is right?
Jan
Jan,
Theoretically, yes. But nobody has ever proven the theory.
The finest firearm barrels made for lead bullets were always choked, as well. Even those that were loaded from the muzzle– which many supposed would cancel the choke effect. Yet they worked just as well as a breechloaded choked barrel.
B.B.
B.B.
Hey B.B.
I know you said there are no springers with an intentional choked barrel. Does that mean the Beeman R9’s barrel isnt choked either???
R9,
When dovetails for front sights are swagged into the barrels the bore is accidentally choked. It isn’t intentional, nor it it controlled. The R9 may have such a “choke.”
B.B.
This is entirely incorrect. Just ask Weihrauch yourself.
Here’s what Hans-H. Weihrauch of Weihrauch & Weihrauch Sport GmbH & Co.KG has to say on the matter:
‘Probably there is an ongoing debate. We have already confirmed several times, that our barrels are chocked. But some how the people are discussing it again and again.’