Howdy, my first bug report so bear with me a bit. The issue has previously been mentioned however not much traction came to it.
In essence, the M107 shell for the K9 VIDAR is lacking a fair bit of velocity compared to the M107 found on most recently the PzH-2000, but also compared to shorter cannons like that on the M109 and M109A1. It has also come to my understanding that this discrepancy is also the case for other SPHs like the AuF1 and to an extent the Type 75.
As of right now, the M107 has muzzle velocity of 945m/s when fired from the L/52 of the PzH-2000, in comparisson the M107 fired from the L/52 of the VIDAR only has an exit velocity of 563m/s.
To further put it into perspective the descrepancies, ill provide a table with all SPHs to fire M107 and plot in their muzzle velocity, along with caliber. I will also use the M114 howitzer found on the M44 in game as a base for the comparisson as its muzzle velocity is stated on its Wikipedia page and is the same (off by 1m/s) in game.
In the table above is every single SPH that uses M107 in game, looking at the MV (muzzle velocity) of the different guns there is no evidence of any system when it comes to calculation of MV based on caliber. In a former bug report on this issue i came to see that the PzH-2000 uses max charges for its M107 round in game allegedly. This leads me to believe that it is a matter of powder charges, which ultimately would not matter as for example 155mm OE F3 has the same velocity for both guns.
In conclussion, I have done a whole lot of yapping. BUT, the point is that there is a large amount of inconsistencies with gaijin’s muzzle velocities over a range of different SPHs. While i mainly wanted to focus on the VIDAR as it to me has the most lacking MV given its caliber. It occurs to me that other SPHs are also in the realm of needing a newly calculated MV. Why the M109G is so high for example, i do not know, biggest difference between it and the Isreali 109 is that the 109G has a different breechblock, but nothing more.
All in all, #JusticeForM107MV
Sources:
In Game data
Wikipedia for looking up different gun names and their caliber, aswell as specs of M107 fired from M114 howitzer present on the M44