Full Auto M14
Original M14 rifles are selective fire capable. Most (90%?) were fitted with a selector lock, making them semi auto only. After Army testing (troop trials) it was determined that 1) give a GI a selective fire weapon, and he sets it on auto, and leaves it there, 2) the M14 is too light for sustained full auto use.
So they removed the selector lever from most of the M14s, and replaced it with a knob that did nothing.
The M14E2 was to be the automatic rifle (replacing the BAR), and had a staright line stock, forward (folding) grip, bipod, and "muzzle stabilizer" (a kind of brake). It worked, but the basic problem was that the M14 reciever is too light to hold up for sustained full auto use. Crack developed in the recievers of test guns. The real problem with the reciever is that it is too light for the full auto rate. This is also why it is difficult to keep the full auto M14 on target. The cyclic rate is too high. I have heard of a modification to the gas system that reduces the rate, allowing accurate full auto fire, and avoiding undue stress on the reciever. Pity the military gave up on the M14 before they figured this out.
My Small Arms repairman class at the ordnance center (Aberdeen Proving Grounds) in 1975 was the last class trained on the M14 rifle, and as the "test" for completion, we drew a "test" rifle, and went to the performance range. The test rifles had certain defects (listed on a card the instructors had), and our test was to inspect the rifle, find the defects, replace the defective parts, and (of course), properly fill out the 2407 repain form. The form was half the grade! After completing this, we handed the rifle and form to one of the instructors (Army Sgts, and Marine Gunnys), who did a quick check on the rifle, compared the form to the listed defects, and then handed us a 20 rnd mag w/15 rnds. We were to fire 5 rnds semi auto, and 10 rnds full auto (short bursts). Rifle was placed in a firing port in the wall (at knneling height), and we went ahead.
I was the third one finished, and I listened to the guys ahead of me. When they went to full auto fire, they were squeezing off 2 rnds (short bursts, remember), and that is about as short as you can manage.
Now, being a young smart*ss, and having owned and shot a couple of different .308 rifles, I knew the recoil wouldn't be very bad, after all, this was a 9lb semi auto. And it wasn't. I decided that instead of trying for a 2 round burst, I would pull off the classic three round burst. I had previously shot the M16A1 on full auto, and there was no recoil to speak of, although after a while the rifle tried to bounce a bit. And I had fired the M60 machine gun, which just kind of shakes back and forth a bit.
So, here I go, to pull off a three round burst. It was an educational experience. My three round burst was six rounds, and moved me from a kneeling to a sitting position!
Recoil with the M14 on full auto is cumulative. The gun fires so fast, you don't fully recover from the first round before the second is pushing you back, and the next, and the next, etc. Each shot moves you further off target. I was moved to the sitting position, but my weapon did not come out of the firing port. I think that was what saved me from a royal butt chewing! I looked up at the instructor Sgt, who glared at me and said in a voice of thunder "SHORT Bursts!!!". I fired two further two round bursts, and then handed the empty rifle to the Sgt, per instructions.
This was my eye opener to light weight full auto fire with the 7.62mm Nato round. Civilian kids just never have the chance to get any experience with that kind of thing, and I remember it vividly to this day. BOY, it was FUN!
I have one of the older Springfield M1a rifles, mine is made up with milsurp parts (except the reciever of course). My rfear sight has the locking bar, so it is originally from a Garand, and my stock has the cut out for the selector lever mounting stud. It's not a match grade, or anything special, but it is special to me. And it shoots at least as well as I do!
So, when you hear someone saying that you can't hit anything with the M14 on full auto, and that the gun won't take it, know that this is true, and not true. As created and issued, it is true, but with a slowed down cyclic rate, it can really perform. Most of us will never get the chance to find that out from hands on experience, and that is sad.
AR designs in 7.62mm Nato may prove to be as good as the M14 (possibly better for semi auto) now that they are getting all the bugs worked out. But they will have to go a long way to be a better battle rifle.
A good M14/M1A is the "ultimate Garand", and you have to work hard to better that.