Yep, and Gus asked me for my notes on these conditions on commercial receiver makes, a few months back. It is common in all makers of the M14 type receivers today. Here are a couple of pics of an M14 build that shows this condition in a commercial receiver. The owner of it, sent it to me through another competitor that I built one for, to see if I could help him figure it out. I will not name him, so please do not ask.
![lrb m14 762x39 lrb m14 762x39](https://www.mrcolionnoir.com/wp-content/uploads/2020/05/firearms-banned-in-canada-fb.jpg)
This rifle was sold as a receiver only from CMP, and was built by a very well known builder in the business, for a fellow shooter. This will open your headspace up when you fix it, unless you change bolts to find one with longer lugs, or longer measurement from the cartridge seat face to the rear of the lugs. When there is only one side contacting, the bolt will not settle in the same place every time, thus affecting accuracy.
![lrb m14 762x39 lrb m14 762x39](https://www.americanrifleman.org/media/mb1f05bb/6-reasons-to-reconsider-the-m14-6.jpg)
![lrb m14 762x39 lrb m14 762x39](https://calibremag.ca/wp-content/uploads/2015/12/DSC_0128.jpg)
It also will increase the accuracy of your rifle, by having good contact on both sides. The safety lug is the one on the left rear of the bolt, so don't let any non-informed smith, tell you that the left side is for safety and contact is not important. That is why the lugs are there, to be utilized. You want to have every last opportunity at protection for your safety, in the event of a catastrophic explosion. Those of you that buy rifles from the CMP, or another individual, or buy a receiver to build yourself, or have one sent off to your armorer, or any existing rifle you have right now in your ease check this condition on them, or tell your smith to check it, and correct it. I am finding that this is an all too common problem with all of these type rifles, and not a setback problem brought about from extensive firing. The receiver was manufactured with the left lug out of spec, and too far rearward from datum. The bolts were all the same, and good to go according to the specifications from the government blueprints. I know several of you will say, or think, "well, it was just a bad bolt". When you do, you will see unencumbered light coming through all the way, on a bad receiver, bolt combo. You have to move your heads position (eye) back and forth, back to front, and move the light the same direction, until the two line up even with the gap. An old worn No-Go headspace gauge will work too. This puts rearward pressure on the bolt face while you inspect it. The best way is a snake light under the bottom, and a sized case that is not factory, but longer, like a fired case, in the chamber. It is a quick way to find out about contact at the lugs, but not always. Roll your spent brass on a flat level tabel top to see this effect in a one lug contact rifle like the M1 or M14.
#LRB M14 762X39 PLUS#
Plus the fact that ejected brass will be jerked out unevenly at the cannelure and cause it to be useless for accuracy type reloading. It may in fact be strong enough, but the design calls for two sides contacting, not one. Now some will say that the one right side lug, being so long down the receiver rail and decelerator ramp, is strong enough to handle the pressure of firing, without left side contact. It is not, and is more common than many realize. This is not the first one like this, and I thought it was an anomoly, or fluke on the others.
#LRB M14 762X39 FULL#
001 below the minimum of 1.940 and the rifle would not function a full cycle for the owner. 003 at the left lug, and a 20% contact on the right lug. 008, and this weekend, I had a military Springfield Armory M1 in my shop that showed a gap of. I have been finding many commercial M14 types with the left lug gap of between.
![lrb m14 762x39 lrb m14 762x39](https://i.ytimg.com/vi/wWezgMUs6B0/maxresdefault.jpg)
They do this because they know, they absolutely know, without a doubt, that the M1 is good to go because it was manufactured by the government backed producers, and closely checked. A false sense of security penetrates into the circle of people seeking info on military small arms and deciding to build them theirselves, and among armorers, and they go about their business as usual without looking closely enough. It may have been just that way, but that is the way that complacency oozes into the mind. You will also find that the armorers never lapped bolts because it wasn't necessary to do so, because lug contact was so good, directly from the manufacturing companies, and that part interchangeability was the end goal, under battlefield conditions, and is easily accomplished now. Almost everywhere you go to find information about this, you will be told that the production of these rifles was closely watched, and that quality control was excellent. For several years now, I have been reading and studying the complete history of production of these rifles, and the specifications of same. This is an informational thread, primarily for builders and smiths that specialize in the M1 and M14, or any of the other rotating bolt, semi-auto, center fire rifles in this class of small arms.