Jam-o-matic?

by
posted on April 29, 2022
rifle breech

Multiple culprits such as fragments from a broken ejection-port cover (which is internal), an overly long scope-mount screw or potentially damaged guide rails can affect the range-of-motion of a Remington 742’s bolt-carrier assembly, thereby causing it to malfunction.

In my family, we own five Remington semi-automatic rifles chambered in .30-’06 Sprg.: One Model 74, three Model 742s and one Model 7400. We realize there are other rifles on the market, but we are partial to the Remington semi-automatic. I also realize those rifles have gained the nickname of “jam-o-matic,” but we seldom have any problems with those rifles jamming, except for one of our 742s. The barrel of the offending rifle was changed out several years ago from a .308 Win. to a.30-’06 Sprg., and that rifle has never worked properly since. It will fire the first round, but jams when trying to eject the empty shell casing. When the rifle is loaded with an unfired round and you try to unload it, the .30-’06 Sprg. round will not clear the chamber when the bolt is pulled all the way back. Is it possible the .30-’06 Sprg. rounds are too long for the receiver? I have tried two different magazines, but that didn’t fix the problem.

Should I consider converting it back to .308 Win, or perhaps .243 Win.? Could it be because the .30-’06 Sprg. is a long-action round and the .308 Win. is a short-action round?
Cal Washispack, via e-mail

I hate to admit it, but this one had me scratching my head—so much so I contacted several of my colleagues—all of whom have as much or more professional experience with the Remington 742 as I. One was a gunsmith at the FBI Academy at Quantico, VA, when the Bureau had the 742 as a service rifle chambered in .308 Win. Another is a retired U.S. Marine Corps gunsmith who has his own gunsmithing business. Another retired from the Bureau of Alcohol, Tobacco and Firearms a while back and has more experience in the workings of firearms and ammunition than anybody I know—or have ever known.

After presenting your situation to each of these men, the first question I received from each of them was, “When was the last time the owners cleaned or lubricated the gun?” Since I couldn’t answer that question, we went on the assumption that gun maintenance wasn’t the problem. It became clear that the bolt and carrier were not moving to the rear sufficiently to extract and eject a live .30-’06 Sprg. cartridge. This led us to the assumption that there was an obstruction preventing the bolt and bolt carrier from moving through its full range of motion, since the .308 Win. and the .30-’06 Sprg. Model 742 receivers and ejection ports are the same. Going on this premise, three possibilities that had been seen before by one or more of the committee members came to the forefront, assuming the rifle was clean and all of the bearing surfaces were lubricated.

Ejection-port covers on the Model 742 break all too regularly and have to be replaced. In some cases when the cover breaks—particularly if it separates into pieces—the bolt and carrier movement can be restricted until the pieces are removed. If this is the case, the ejection-port cover can be replaced, usually without totally disassembling the gun.

If the rifle has a scope mounted on the receiver, one of the mounting screws holding the mount to the receiver could be a bit too long and might be protruding into the interior of the receiver. This would effectively restrict the bolt from moving fully through its rearward range of motion, causing the problem you mentioned.

If the rifle in question was an earlier version of the Model 742, the receiver was thought to be made of a slightly softer steel than later models. What this means is the guide rails in the receiver may have been damaged through use or otherwise, which would slow or prohibit the movement of the bolt and carrier and ultimately result in the problem you describe.

In some cases, the damage can be repaired by a competent gunsmith and in other cases you have a wall-hanger, unfortunately.

It is possible that other conditions that could cause the problem you outlined above, but without putting hands on the rifle, these suggestions are what we feel would be the most likely culprits to investigate.

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