I don't know what you mean by "deer ammo". The difference per round of .270 ammo versus .224 ammo is just pennys.

The answer to your question is, yes, a well placed 55grn or 60grn .224 bullet at 3500/3600 fps will get the job done.

Read some of P O Ackley's articles about the .220Swift written in the 1940's.

uj