Today's rifles have barrels that are made on more modern machinery and so the percentage of sub-moa barrels made today is higher then what we had 50 years ago. BUT....The high end of accuracy available then and now is not much different. I remember seeing some shooters make groups in the 1960s that are every be=it as tight as what I see today from top shooters. If we looked at the average size of the groups shot by most shooters then and now, I think tighter groups today are more common, but the very top end is almost the same.

And as noKnees said the bullets we have today are more accurate. The reason I believe we had more good shooters in the 60s and 70s then we have today is 2 fold. #1 shooting was still a very common thing then with high schools all over the western state having shooting teams, rifles and shotguns. Today the socialist mentality so prevalent in schools lies to the kids and tries to convince everyone they can that guns are bad.
#2 powder and primers were a LOT cheaper then, Sure I understand the issue of inflation, but even at the cost of living going up, prices on ammo components have gone up far more at a rate of hours worked to exchange for value in ammo. When I was 12 I could buy 4831 rifle powder for $1.20 a pound and I bought 270 bullets for $4.80 a box and my 270 brass was formed out of range pick-up 30-06 after the National Guard shot there, so it was free. Primers were 40 cents a flat. I worked for $2.25 an hour. 8 hour days paid 20 in cash if no breaks were taken for lunch so the full 8 hours paid a bit more then $2.25.
I could spend it all if I wanted to on ammo and most times I did. So I (and other boys I knew) became very good marksmen. By the time I was 18 I had to have my 270 re-barreled because I'd shot the rifling out of the throat. I am sure the bullets I bought then were not quite as accurate as what I can buy now, but instead of buying a few hundred now and then, I used to buy them 1000 at a time and sometimes 3000 at a time and 4831 was weighed on a scale and carried out of the store in a 1 gallon glass milk jug.

Sign of the times I guess.

I have many young friend today and I take them hunting and I train them in shooting skills but I am saddened at how many of them are not all that good at shooting and can't afford to fire enough rounds to get very good.

My "kiddos" who come to me for coaching and fun run from a 12 year old girl to a 24 year old man with about 7 of them being from 15 to 18 years old. the 24 year old is the best shot of the bunch, but has also been training with me since he was 17. The one boy of 15 is nearly as good but has a ways to go. The one I am most impressed with however is thew 12 year old girl. I made an AR10 for her at the request of her dad (a good friend of mine) and she is showing a lot of potential. The rifle is fairly light as AR10s go, but still comes in at just over 9 pounds with the scope and mount and a full 10 round mag.
She only weight 97 pounds but carries the 9 pound rifle as if it were weightless and is a real go-getter. On Christmas day she was up here and we were shooting at clay birds placed at 250 yards. From prone and she seldom missed one From sitting she gets about 1 in 4. But the misses are usually quite close. Not bad for a 97 pound girl with 4 months of experience using a full size man's rifle ,and I am very proud of her.
She starts hunting this coming season and I think the deer elk and antelope should be very afraid of her.