Looked up a few things
If I understand you correctly, you wish to make the vog-25 and vog-25p make the same amount of damage as the m209, that however is a non-issue as the only real projectile difference is that vog-25 travels a further than vog-25p and m209 by a factor .3.
If you however wish to make other grenade launcher use m209 munition, then all you need to do is add * ammo_m209 * behind * grenade_class = * in the .ltx file of every weapon that uses *wpn_addon_grenade_launcher* (the regular grenade launcher attachment)
For example the Abakan, in the .ltx file * w_abakan * there is a line
grenade_class = ammo_vog-25, ammo_vog-25
To that you would have to add * ammo_m209 *
grenade_class = ammo_vog-25, ammo_vog-25, ammo_m209
Hope that was of assistance.
THE DEDICATED, CERTIFIED RESIDENT MADMAN
There is no such thing as innocence in the ZONE, only degrees of guilt.
CAN YOU FEEL THE TRANQUILLITY OF THE ZONE
Knowledge is power. Guard it well.
We are shaped by fate, just as we shape it
You should never be in the company of anyone with whom you would not want to die.
Akir man yamut malak al-mut