Wouldn't the cost in resources largely be reflected in the cost of production, maintenance and re-build rather than the 1,000 strength value ?
If only 2 or 3 guns then the loss a gun would be a loss of 300 or 500 from 1,000.
The imbalance in losses between infantry, cavalry and guns is decidedly questionable; typically armies lose hordes of infantry, a few cavalry and almost no guns, leaving a depleted army hugely imbalanced.
Cannons come in batterys, not regiments (except perhaps for admin. purposes), batterys perhaps typically of 6, though not always.