Hi glynd02!
Several AGMs are available in-game and they differ in their lock on precedure, guidence system, warhead, etc...Be aware that in some missiles like the AGM-65E you'll need to manually Enable the weapon system engagement. To do this hit the same Hotkey you have for your brakes (usually it's B)
There are 4 types of AGMs in-game and here's a little guide:
AGM-12B Bullpup: Radio-guided Air-to-Ground missile. These missiles are manually controlled and guided towards the target; to control them you need to assign the required "Steer Guided weapon Up/Down/Left/Right" hotkeys in the Controls section. They have a very powerful warhead but they require a bit of practice to get used to them. Launch from afar while facing the target and gently hit the controls to accurately steer them to the target.
AGM-12C Bullpup: Same as above. More powerful warhead.
AGM-12E Bullpup: Same as above. The conventional warhead has been replaced by a cluster warhead. This missile will explode in mid-air just a few meters from the ground and cover a wide area with small explosive ordnance (same effect as Cluster bombs)
AGM-65B Maverick: Laser-guided anti-tank missile. The well-known Maverick carries an heat-seeking/infra-red seeker head that enables it to automatically lock on vehicles, tanks, guns and ships. Once locked on, just fire and forget. Bear in mind that the warhead is indeed powerful, but it's HEAT, so super-efficent against any target IF IT HITS. You'll be disappointed on how inefficent and unreliable the Maverick is depicted in Il-2. The seeker is great, although this version is limited only in daylight-ops, but the warhead HAS NO SPLASH DAMAGE (
i personally think it should be buffed...)
AGM-65D Maverick: Same as above. Modified for all-weather specifications and usable for night ops.
AGM-65E Maverick: Laser-guided anti-tank missile. In this special version the seeker is modified to work together with the FLIR you have onboard. To use it Switch Positions and look through your FLIR camera: align the green crosshair with the selected target and then hit the assigned hotkey for "Misc_7" to Lock On. Once the target is locked, release your ordnance. The warhead is still disappointing and, ironically, it's even worse! The fact that you must manually aim them really destroys its capabilities as a pin-point accuracy AT weapon...It's basically impossible to aim them at moving vehicles, and even if you hit them there is a good probability of not killing them (even trucks and AA guns). Their only good use is as anti-building, where the target is STATIC and BIG ENOUGH to lock.
AGM-65F Maverick: Same as B and D. Improved range and seeker. Probably the best version of the series, ditching the previuos FLIR aiming system
AGM-84D/J Harpoon + Sea Eagle + AS.34 Kormoran: Infra-red/Radar guided anti-ship missile. The Harpoon is a very easy weapon to use: just look towards the general direction of the ship you want to sink and it will lock on it. Fire and it will guide itself towards the unlucky ship that has been selected as a target. The warhead and guiding system is absolutely deadly.
AGM-84F Harpoon: Still to test
AGM-123 Skipper II: Laser-guided anti-ship bomb/missile. This guided weapon works in conjuction with the FLIR; to use it Switch Positions and look through your FLIR camera: align the green crosshair with the selected target and then hit the assigned hotkey for "Misc_7" to Lock On. Once the target is locked, release your ordnance. Remember to maintain a good lock on target until the bomb is near it. The warhead is composed by a 1000lbs Mk.83 bomb so it will annhilate most ships and work very well against ground targets if in proximity.
AS.30: Infra-red guided Air-to-Ground missile. The AS.30 can be found only in the Canberra B(I) Mk.8 and it works with a sort of mix between a heat-seeking and a radar-guided sensor that enables it to work much like a Maverick. It can easily lock on vehicles, tanks and ships. Unlike it nevertheless, the warhead is way better and the blast radius is great for a missile.
Let me know if you need a guide also on soviet/russian AGMs or on guided bombs.