You can back test this fund a Morningstar.
https://www.morningstar.com/funds/xnas/prgfx/quote.html Too bad they don't start their S&P500 series until a couple decades after the fund started, but they do have a house "large growth" index to benchmark against, which was presumably an agglomeration of other large cap growth funds. We'll compare by decade, April 11, 1950 to April 11, 1960, etc. Comparing growth of $10,000.
1950-1960
PRGFX 56,416.96
"Large Growth index" 41,837.31
But don't get too excited. The dude who managed that ain't around no more.
1960-1970
PRGFX 27,296.89
"Large Growth index" 22,463.35
That dude ain't around no more neither.
1970-1980
PRGFX 12,467.02
"Large Growth index" 18,407.04
Lucky, neither is that one.
1980-1990
PRGFX 34,151.65
"Large Growth index" 46,727.33
That guy is possibly still around, but no longer managing, fortunately for shareholders.
1990-2000
PRGFX 54,195.39
"Large Growth index" 59,562.68
I hope that guy is not still calling shots. Probably not. Losers don't stick around.
2000-2010
PRGFX 11,091.16
"Large Growth index" 7,138.30
Oooooh good job manager! Made money in the lost decade! Is this even still a guy? So much for the good ol days of gender determinism.
2010-2019
PRGFX 34,267.56
"Large Growth index" 28,023.27
Looks like PRGFX beat its benchmark in 4 out of 7 ten-year periods. Good job. What are the odds for the next 10 years? Remember that the first 50 years have no bearing on the performance of the current fund. The managers, market, and methods have all surely changed entirely. Also remember that 99% of the funds started back then didn't make it, and a priori you did not think of them. This fund is like the winner of the NCAA basketball tournament: is the winning team really the best, or was the tournament merely structured in a way such that a single team was guaranteed to win? That said, it seems to be a tolerable fund. The cost is high but not outrageous. At least it doesn't suck (yet, by the fact we even looked at it). Just remember: you have a 4/7 chance of beating the market based on history that is water under the bridge, but a 100% chance of the extra 0.6% expense ratio.