The Bulged Chamber: A Simple Fix

It’s never fun when we encounter a bulged chamber in an otherwise fully functional rifle. One common "fix" is to replace the barrel, but with unusual rifles this isn’t practical, because of special contours, proof marks, or even engraving. Rechambering to something with a fatter case is sometimes possible, but probably seldom as desirable as leaving the rifle in its original chambering.

If your customer brings in a rifle chambered for the .228 Geewhiz Flashbang, chances are he’d probably like to keep the rifle in that chambering. There are, of course, varying stages of bulge. A bad one would probably be sufficient cause to replace the entire barreled action, or even the whole rifle. If it’s a truly bad bulge it’ll be obvious, with a bulge in the action, and maybe even a burst barrel, and then you’ve got a real mess.

But often the bulge goes almost unnoticed until the next round is fired and the shooter experiences a sticky case. If this occurs, the common reaction is to assume the load was a hot one and try again. When the same thing happens, the prudent reloader (reloaders are the ones who are generally troubled with bulged chambers) goes home and loads up a batch of reducedcharge ammo, and tries it again. When this, too, sticks, the shooter figures something is wrong, and will eventually diagnose a bulged chamber.

Another problem is that a shooter may unknowingly buy a used rifle with a bulged chamber, take it to the range, get sticky cases, and not know exactly what’s wrong, especially if he’s never encountered such a thing before. This is exactly what happened to me with an otherwise fine rifle and, after some ardent head-scratching, I found what the problem was. Even better, I came up with a relatively simple cure that you might find worth a try if you ever come across the problem of a slightly bulged chamber.

Some years back, I bought a 1905 Mannlicher Schoenauer carbine in its original 9×56 MS chambering. I got a few Kynoch loads for it, and when I tried them in the little rifle’which appeared to be in outstanding original condition throughout’t he spent cases stuck in the chamber. The Mannlicher Schoenauer has never been known for its great extraction power, so I didn’t think too much of it at first. Some time later, I tried handloads in the carbine.

It has recently been determined (by the Mannlicher Collectors" Association and others) that 1905 M-S carbines and rifles had one of three bore sizes. They were either 0.353", 0.355", or 0.358. Mine was the smallest. I bought some bullets that measured 0.348" (all I could get at the time) and assembled some mild loads. These stuck too. I disassembled the bolt and found a quarter-inch of the firing-pin spring was broken but still in place.

When I removed the broken piece and also cleaned some dried oil from the bolt innards, cocking got a little easier, so I hoped I had solved the problem. But fired cases still stuck in the chamber. I thought perhaps the chamber was rough or pitted, so I gently polished it, Rebarreling would most likely be out of the question, so "fix it" or "don’t shoot it" covers the options. This rifle is from the first year of production and is in alloriginal condition.

Only the lightest reloads came out easily, indicating a slight but solvable problem. The 9×56 slings 245- to 250-grain bullets at 2,100 fps, a potent round for a 6.5-pound rifle. The chamber cast also provided the solution to the problem. The author sawed off the front portion of the chamber cast, and then turned the front of the remainder down so it would not touch the chamber. He then drilled and tapped the plug to accept along brass rod, making a chamber lap out of the assembly. again, to no avail.

These hopeful attempts to fix the problem took place over several years, during which time I moved, and subsequently lost interest in the little rifle when I could not come up with a solution. Just recently, I made a chamber cast of the Mannlicher, and when I bumped it out of the chamber and measured it, I found there was about half a thousandth of an inch of bulge in the chamber. The first two-tenths of the chamber was the smallest diameter, and the main body was just a touch larger.

The proverbial light went on over my head, and I got to work. I used the bottom half of the chamber cast that I had just made, cutting it off to about 3/4 inch in length. Then, with my lathe, I turned all but the By bumping the grit-anointed chamber cast into the rear of the chamber, the grit on it cut out the portion of the chamber that was causing sticking cases.

A series of chamber casts would tell the tale more accurately, and would give better feedback on over-cutting the chamber. bottom quarter-inch smaller so the forward portion would not touch the chamber. Then I drilled and tapped an axial hole into the chamber cast to accept a threaded brass rod (an old cleaning rod worked fine) that was long enough to reach through the barrel, out past the muzzle. I screwed the rod into the forward portion of the modified chamber cast.

I then anointed the large portion of the chamber cast with 150-grit valve-lapping compound, and inserted it into the rifle’s chamber with the rod protruding out the muzzle. I grabbed the rod with the chuck of my cordless drill and proceeded to lap the last .2 inch of the chamber. That last little bit of the chamber was keeping the very-slightly expanded fired cartridge case stuck in the chamber. I bumped the plug/lap in and out of the chamber as the lap spun, and in short order had removed a bit of metal.

I cleaned it all up and looked, thought about it, and then did a bit more. With everything cleaned up and put back together, it was time to head for the range. This time I had some 250-grain bullets of the correct diameter. These were made by Hawk Bullet Co. after shooters like me asked long and hard to get them. In my experience, Hawk has been very obligcontinued on page 15)

ing in giving shooters what they need and can’t get elsewhere. Imagine my joy when the fired cases nearly fell from the chamber. When this much of the lap had entered the chamber, the author assumed he had done enough lapping. This fixed the slightly bulged chamber perfectly, and restored a superb rifle to healthy status. The dark portion is what did the work on the chamber. Bolt lift was easy’t he first time I’d experienced that since I bought the rifle.

I worked up a series of loads that eventually gave the correct 2,100 fps to 250-grain bullets. Now, after years of worry, doubt, and frustration, I finally had the powerful little carbine I had paid for long ago. My simple lapping operation was a complete success, and very easily accomplished, once I had a clear picture in mind of what needed to be done. My now quite valuable little Mannlicher carbine is finally in perfect operating order, and best of all, it’s still in the original chambering.

So if a customer brings a rifle into your shop with a sticky-case problem’ even with light loads’t his simple trick might work for you, too. I