I own an M40/M40A1 and P99 in the AS (double action trigger)
The P99 has been around a bit longer than the M. The grip on the P99 has a very very slight edge over the M. The grip on the MA1 has been changed and is just about as nice as the P99.
The P99 has a higher bore axis and is a lighter gun so muzzle flip is more pronounced.
Steyr seems to have one of the best feeling triggers in a striker fired gun.
While I have had no problems with either of my Steyr's others have . The P99 has an excellent reputation for reliability.
If mounting a light to your weapon is important the P99 still doesn't accept "standard" accessories but Steyr will.
P99 holsters will be a bit easier to find than Steyr.
The Steyr should also sell for around $100.00 or so less than the P99 and magazines are less expensive.
I also think that the Steyr is a more robust design
The P99 has been around a bit longer than the M. The grip on the P99 has a very very slight edge over the M. The grip on the MA1 has been changed and is just about as nice as the P99.
The P99 has a higher bore axis and is a lighter gun so muzzle flip is more pronounced.
Steyr seems to have one of the best feeling triggers in a striker fired gun.
While I have had no problems with either of my Steyr's others have . The P99 has an excellent reputation for reliability.
If mounting a light to your weapon is important the P99 still doesn't accept "standard" accessories but Steyr will.
P99 holsters will be a bit easier to find than Steyr.
The Steyr should also sell for around $100.00 or so less than the P99 and magazines are less expensive.
I also think that the Steyr is a more robust design