I have no experience with the Vit N310 but it is very similar in burning speed to Bullseye.
Normally, it is VERY unwise to try to extrapolate a load by comparing burn speed charts but, in this case where you are looking for a very reduced velocity, I think we can proceed just fine.
The max Bullseye load for a 125grn lead is 4.9 for 1165fps. Considering that, I would start with maybe 3.5grns of the N310 and see if the pistol functions properly. 3.5 will be plenty to get the bullet out of the tube and should have little chance of sticking one.
I am assuming that you are shooting a short barrelled pistol. If this is for a carbine, I'd bump the initial load to 4grns to make sure it makes it to the end of the barrel.
Most 9mm pistols will have trouble functioning reliably with a 115 in the 700's so your load development will consist of finding the minimum needed for reliability rather than a specific velocity.
If the 3.5 load works well, gradually reduce it until the pistol fails to eject or feed. Go back up a couple of tenths and call it good.
Of course, if the 3.5 doesn't run the pistol well, increase by tenths until it does.
If you cannot find the specific load info you desire, at least in this case, you can work up your own safely so long as you realise what you are doing and proceed gradually. Good luck.