The bipod only/mg configuration should definitely be reserved for weapons like the NTW-20, which are not man-portable or possible to fire off-hand.
The 25mm Payload Rifle "only"
weighs 30.5 pounds, which is comparable to a GPMG like the M-240B which weighs about 22 pounds empty. Not fun to lug around by any means, but definitely do-able. Also, it is theoreticaly possible to fire off-hand (although it would be extremely uncomfortable due to much less body mass being involved in soaking up recoil). Thus IMHO, it should be configured as a "normal" rifle-type weapon, but with massive recoil in the crouched and standing positions. In the prone, I would configure the recoil to be signifigant enought to put the shooter off target after each shot, requiring adjustment of aim (this is actually realistic for just about any high powered rifle fired with optics, and is one of the the main reasons snipers require a spotter {an issue addressed in my soon to be released MOD BTW}). I would definitely model all sniper type weapons with bipods extended (a nit pick I have with some rifle models out there).
I will look for a suitable pre-existing Barrett out there with good textures and accurate modeling, and naturaly I'll ask the author for permission to modify his files. This should signifiganly cut development time.
More on round configuration: The 25mm round does most of it's work through the armour penetrating HEAT warhead, not sheer kenetic energy (actually much more efficient and easier on the shooter in terms of recoil and weapon system size and weight). Thus the round should have a lower velocity and more pronounced arc than, say, a .50 cal. Ballistic data on the 25mm is not forthcomming so In my approxamation I would say it should have ballistics (for game purposes) similar to the JAM 7,62mm SD round. This will also help in terms of play balancing and make the player have to consider trade offs/pros and cons when chosing it over a HTI rifle with higher velocity and less arc (higher hit probability) for instance. Giving the player distinctly different options to achieve a task helps to immerse them into the game world, and is very critical to replayability and such. The 25mm would have the following advantages:
Man-Portable and highly mobile, larger magazine capacity, consistent armor penetration regardless of range, signifigant indirect damage capability for soft targets
Disadvantages: Higher learning curve due to more pronounced trajectory and lower velocity would make engaging moving targets very difficult.
The NTW-20 advantages:
Two ammo types increase flexibility/lethality; AP (slightly more raw direct damage than the 25mm, but no indirect, and increased chance of injuring crew due to spalling) and HE (less direct/indirect damage than the 25mm), High velocity increases hit probability. Definitely the "cool factor"
Disadvantages: Two-man weapon sytstem taking longer to deploy, Fairly rigidly emplaced once positioned, lower magazine capacity.
Well if you waded through all this... thanks! I tend to be a bit detailed about this stuff
-Grendel
BTW, finally downloaded PBO decrypt/makePBO and played around with a Barrett. After some experimentation, the ideal damage value for HTI ammo is as such:
25mm HEAT:
hit=175;
indirectHit=50;
indirectHitRange=5.000000;
explosive=1;
20mm AP
hit=225;
20mm HE
hit=100;
indirectHit=25;
indirectHitRange=2.500000;
explosive=1;
These values seem to be pretty balanced, taking 2-3 shots of "25mm" to disable an APC (without any additional scripting trickery). 20mm AP will usually yield a catastrophic kill in 2 shots.