4.0.2+ - Carrying Capacity

[dnabgnayalpem]

I was just looking at players_calc.c and I notice that the carrying capacity hits a limit at 30x10 LBs (300 LBs),

...
28	/* 18/40-18/49 */,
30	/* 18/50-18/59 */,
30	/* 18/60-18/69 */,
30	/* 18/70-18/79 */,
30	/* 18/80-18/89 */,
...

but my character with 18/50 (18/80 strength with ring) has this inventory statement on weight:

Burden 197.3 lb (17.4 lb overweight)

So, why am I becoming "overweight" at about 180 lb if carrying capacity for my strength is 300 lbs ... is this a bug or by design?
Overweight threshold is 60% of max carrying capacity?

And why the 300 lb max limit?

Inventory and weight management are become a really challenge...