Why don't I see long skinny 90 gr bullets in the 22-250 that have much better BC? I understand they'll shoot slower than the 50 gr bullets, but has anybody even tried? I know to keep the same OAL, you'd have to seat the bullet in deeper. Is it even possible with current heavy grain bullets in 22 diamater?
It's possible and you can get a barrel with the faster twist needed, but you'll have to order it special (aftermarket usually)
I have heard that some 1-14 twist gun's do handle the 60 gr alright but not enough experience with the 22-250 to really say.
Some do, some don't, it depends on the gun, and what one considers "alright". For a long time the 60+gr slugs were the heaviest and were considered the "deer bullet" where allowed by game laws. I've got a Win M70 Varmint (1-14 twist) and the Sierra 63gr Semi-spitzer was a consistent 1.5-2moa bullet in that rifle. Good enough to take deer, not so much for small varmints. 52-52gr match bullets would do around 3/4 MOA when I was that good and 55gr SP would be 1 MOA or a bit better.
What I don't get is the fascination with heavier than 55 gr in any 22CF. If I wanted to shoot heavier than 55 gr bullet's I'd go to the 243!
The long heavy for caliber high BC bullets were developed by folks who wanted to win military long range matches shooting AR 15 class rifles. Going to a .243 or larger meant an AR-15 couldn't be used. The VLD type bullets kept enough speed far enough, and bucked wind well enough to compete successfully against larger calibers and kept the advantage of fairly light recoil. Faster twist .223 barrels were needed, but those got made, too, in order to win a shooting game.
The .22-250 began life in the 1930s as a varmint cartridge, and became factory standardized in 1965, still decades before the heavy bullet VLD type idea took hold anywhere.
Not being in the AR-15, and so not used in those kinds of long range matches, the fast twist heavy bullet thing simply didn't catch on with the .22-250, which has retained the varmint rifle twist rate it always had.
You could get a custom fast twist barrel chambered in .22-250 and if so, it would do what the fast twist ARs do but some 400fps or so, faster.
Except it won't fit in an AR-15. AR-10, yes, AR-15, no.
The changes to the M16 that began with the A2 variant have led to making the AR a VERY accurate rifle, and AR-15s are allowed in "military rifle" matches (since the actual select fire M16s are very restricted)