Can loose barrels be accurate?
by Tom Gaylord
Writing as B.B. Pelletier
This report covers:
- In battery
- A lathe compound tool rest
- The point
- Pistols with fixed barrels
- M1911 — the barrel movement champ!
I’m doing today’s report for Peter, a reader who expressed concern over the looseness of the barrel on his SIG P226 X5 BB Open pistol. He noticed that when the slide was back after the last shot, the barrel seemed loose and he wondered if that had any impact on accuracy. He is getting dime- and nickel-sized groups of BBs at 15 feet, which he thinks are good and I would agree. But — is he missing out on anything because the barrel is loose? It’s that age-old question — I like what I have now, but is there something more that I don’t know about?
This is a subject a lot of readers probably ponder, but nobody ever addresses it. And I normally wouldn’t address it either, except it is necessary that we understand what’s happening so we can appreciate out airguns to the fullest.
Allow me to begin with a short discussion of the breakbarrel spring rifle. I know it doesn’t sound like the same thing that Peter asked about, but stay with me — because it is.
New airgunners tend to think that breakbarrel airguns can’t be as accurate as fixed barrel airguns, simply because their barrels move when they are cocked. How could they possibly return to the same place every time? And yet, there is overwhelming proof that they do! Vintage 10-meter target rifles like the Diana model 65 and the Walther LGV will drill their pellets through the same hole — one after another. Even though their barrels are broken open during cocking, they always manage to return to the same place every time.
Walther LGV Olympia is a very accurate breakbarrel.
That place is called “in battery.” It’s not really, but I’m going to use that term, because it describes so accurately what is happening. In battery is a term that comes from artillery. After a cannon barrel recoils several feet upon firing, the recoil mechanism pushes it back to the same place it started. That way the shell leaves the muzzle at the same place every time. You may recognize this as my explanation of the artillery hold.
I saw this happen hundreds of times on the inside of an M60A1 tank turret when the 105mm M68 cannon fired. The breech recoiled back several feet and extracted the empty shell that fell to the floor of the turret, while the cannon barrel was pushed back into battery by massive coiled steel springs. We considered our gun accurate if we could put several shots through a 24-inch circle at 1,200 yards.
A breakbarrel pellet rifle has a definite place for the barrel to be when it is closed. Target rifles have precision pads and shims to locate the base block precisely when the barrel is closed. If the base block is always in the same place, the barrel it holds will also be in the same place every time. This is difficult for some new airgunners to accept, but it’s true nonetheless. It’s why breakbarrel target rifles can be so accurate.
A lathe compound tool rest
If you have difficulty with my cannon analogy, here’s another one. The compound tool rest that travels along the lathe bed ways on a lathe carriage moves all the time — that is its function. Yet it can be set to return to the same place every time. If that weren’t true, precision machining would be a lot more difficult than it is.
A lathe tool rest on its carriage (center) moves all the time, but is extremely accurate.
The point I am trying to make is that something can move but can also return to the same place every time if it is designed to do so. Now let’s talk about pistols.
Pistols with fixed barrels
Most centerfire pistols today have barrels that move. In fact, that has been the case since semiautomatic pistols were first invented, back in 1893. The very first semiautomatic pistol was called a Borchardt, and although its barrel appears rigidly mounted to the casual observer, when you examine it closely you discover that it is mounted in a frame that moves as the action cycles.
The Borchardt was the Luger’s predecessor and features a barrel that moves in recoil to kick open the trademark toggle lock. Photo used by permission of Rock Island Auction.
I don’t own a Borchardt, so let’s look at its most popular offspring, the Pistole 08, or what we know as the Luger. Most people look at a Luger and think that the barrel is fixed. They think the toggle lock is what controls the breech. But before the toggle can open, the entire barrel has to move backwards by a fair distance to engage the cams that break open the toggle joint. The barrel is attached to an upper receiver that slides in rails located in the lower receiver. In fact, to disassemble the Luger you must first push the barrel back about a quarter-inch!
The Luger barrel looks fixed, but it has to move back in recoil so the circular toggle cam (the round black thing) contacts the cams on either side of the frame (the ski jump at the rear of the pistol).
It’s very difficult to find a fixed barrel on a semiautomatic pistol of any size. They are found mostly on .22 rimfire pistols, because the recoil of the cartridge is not excessive. Most gas-operated and recoil-operated semiautomatics have barrels that move in some fashion when the gun is fired. Therefore, they have to be designed so the barrel returns to battery every time the gun fires.
Small caliber semiautos like this High Standard pistol are some of the only ones with fixed barrels.
M1911 — the barrel movement champ!
The M1911 pistol barrel moves intentionally when the gun fires. John Browning designed the barrel to be locked to the slide, so when the gun fires, the barrel tries to move back and imparts a rearward push to the slide. But the barrel is held fast to the lower frame of the gun by a link, so when it reaches its limit of movement the link pulls it downward, unlocking the slide and allowing it to continue to move back. The movement of the slide accomplishes all the actions necessary to operate the pistol — extraction of the spent cartridge, compression of the hammer spring, and stripping and chambering a fresh round as the recoil spring returns the slide and — get ready for it — LOCKS UP IN BATTERY!
The two lugs on top of the barrel fit into the machined slots in the underside of the slide. The barrel link (arrow) moves the barrel down and away from the slide when it is moving backwards in recoil.
The barrel bushing (arrow) holds the muzzle tightly. This is where part of the 1911’s accuracy comes from.
When the slide is back, the barrel flops around loosely. When the slide goes forward, the barrel bushing at the front and the barrel link at the rear lock the barrel tightly.
As the slide moves forward, the barrel link lifts the barrel up and allows the barrel lugs to engage their slots on the inside of the slide. There is more to it than that, of course, but those are the highlights. Loose barrel with the slide open and tight barrel with the slide closed.
The barrel bushing at the front of the pistol and the fit of the barrel link at the back are what keep the barrel in perfect battery every time the gun fires.
Peter, I didn’t report on the P226 because I don’t own one, but what I have written today applies to all semiauto pistols. The short answer to your question is yes, the barrels on semiauto pistols can be loose — as long as they lock up in battery before the gun fires. The term in battery does not just mean tight and without and looseness. It also means being in the same place, time after time. It is the basis of accuracy in many firearms and also the basis for the artillery hold we airgunners use.