Do breakbarrels loosen at the joint?
by B.B. Pelletier
This is an answer to a question asked last week: "I was wondering if breakbarrel springers ever wear loose at the hinge and become inaccurate?" That's a common question that deserves an answer.
Some history about the ancestors of modern breakbarrels
You must understand that spring-piston airguns are a more recent development. They're just over a century old, so there's not a lot of real history to support this answer. The earliest models were made with soft iron frames and they DID wear, as our reader suggests. One of the more popular types of breakbarrels are the Gem-type rifles, and they almost always wear loose.
On a good modern airgun, the joint compensates for wear
Coming to the recent past, breakbarrel design has been improved to the point that wear has become a non-issue. Most quality breakbarrels, such as the Beeman R1, have some kind of thrust washer to provide a lower coefficient of friction at the joint. When airgunsmiths tune a breakbarrel, one of the things they do is lubricate the thrust washers and the pivot bolt with some good heavy-duty lubricant to further reduce friction.
The pivot bolt is the fulcrum as well as the axle around which the barrel rotates when the gun is cocked. The mark of a good breakbarrel is a wide-diameter bolt to spread the cocking load as broadly as possible. They all have bolts that can be adjusted to take up any slack that might form over time.
The spring-loaded detent assures a good breech seal and barrel lockup
Besides thrust washers and thick pivot bolts, breakbarrels rely on a spring-loaded detent to maintain pressure on the breech joint when the barrel is locked up. The best detent, in my opinion, is the chisel type. It pushes the hardest because it has more travel by design than the ball bearing type that RWS and the Chinese companies use. Still, I've never seen an RWS (Diana) breakbarrel with a loose joint, so I guess the ball bearing works well enough.
If you DO find a loose breech joint, tighten it!
It's the owner's job to watch the breech joint for looseness and adjust the pivot bolt when necessary. If you grab the barrel and can wiggle it side to side between the action forks, the breech joint is loose. Consult your owner's manual for instructions. Lacking a manual, tighten the pivot bolt until the barrel remains in any position after the gun has been cocked.
I hope this eases your minds about breakbarrel guns. They really don't have problems with loose joints any more.