I'm loading 22-250 rounds with a Hornady 55 grain spire point - does anyone know a reccommended OAL? I've got one source saying 2.350" (IMR chart). Does this sound about right?

OAL of any cartridge depends on the firearm you are using.

Like Steve said, this varies from gun to gun. The number you have is probably the SAMMI spec, which allows it to fit in any 22-250 you use. Most 22-250s like the bullet seated .005-.025 off the lands, which is greater than the SAMMI spec. You need to find this distance and then seat the bullet accordingly. It takes allot of experimentation.

Whoops! I meant SAAMI. Not SAMMI

Could I find the cartridge OAL by doing the following?

Resize & de-prime a case.

Seat a bullet, with cartridge OAL more than needed.

Chamber the round, letting the bolt push the bullet into the case (bullet would be touching the lands at this point)

Remove the cartridge, measure it, and reduce .010-.015" for charged cartridges.

Would this be an acceptable way of finding OAL for this gun?

The thing you have to be cautious of is if the COL you choose/decide will fit into the magazine or clip!
No fun to load up 30 or 40 rounds and find they won't fit!!!

Hollywood

If you try to measure your COL with the bullet loose in an empty case, just barely insert the case in the sizing die. You want the neck squeezed down the least amount possible so that the bullet will slide in the neck with finger pressure, but enough friction to hold it in place. If you resize the case all of the way, the neck may be to tight to allow the bullet to slip without being deformed by crushing it into the lands of the barrel.