Here's some 190 vs P 51 feedback from the arena:
The P 51 is such a great HO machine because of the .50s, not despite of them.
Their effective range, velocity and relatively flat trajectory make P 51D superior jouster to 190, IMO.
Judging by numerous sorties in AH 190, 4 MG 151/20, it is a waste of ammo to fire them at ranges longer than 350 yards. Of course some shells would hit, but rarely it will do any significant damage. Dispersion is simply that great.
On the other hand, I have seen dedicated P 51 jousters in action. Preparing for HO at d25-30, opening fire at d12 (my FE), and I was damaged before we passed (on my FE). Thankfully to net lag was, I was able to deliver deadly hits to them, after opening fire at some d4-5. Usually I was dewinged at d2.
Now I avoid HO against P 51s and Spits in 190. If it is historical....hmm, I don't know.
But for real dispersion freaks, you should fly MK 108 equiped 109 ! Very hard to hit, d3 is usually max range for dead 6 shots, snapshots are an art of itself, but when you connect.....well, something about that feeling when you nail someone with 90 degrees deflection shot of a 30mm

Reminds me of throwing rocks at a running cat

Everything must be planed, opponent moves must be anticipated greatly in advance. Now add compression at high speeds and nose bounce at low speeds, relatively poor 109 down elevator (hmmm !!), mostly poor 109 roll.....you get the picture.
Dead 6 shots should be avoided, in fact. If the opponent does even moderate turn and you follow, 30mm will fall behind him. In HO he will probably fly through the 30mm stream. What counts are planform shots, usually after break turns. Split S can also be hit (by snapshot, not tracking).
Buffs can also be brought down, but it seems slightly harder in latest version.
After MK 108, every gun feels like a laser. Still, I like the MK 108 in 109 nose. Makes you work for the shot. 1 kill per sortie feels like a 3 kill sortie in most other planes.
[This message has been edited by Hristo (edited 12-16-1999).]