I was in a thread not long ago talking about subsonic rounds for a 308win.
I would like to start this thread to be all about subsonic loads for all chambers.
Myself I load a handful of different calibers in different actions.
So if you have any data to share or links to post on said topic, please share.

I have made a subsonic load for the 7.62 x 30 (Little Russian). I use .3 cc of Unique behind a 65 grain lead dome-shaped bullet. The bullet is made by sizing down a .350" lead ball to .311 in a Lee .311 bullet sizing die. Sizing the lead ball leaves a bearing surface on the bullet making seating and crimping easy.

The results are a round that goes off like an oversized 22LR. You can see the bullet's impact on small game through the scope. There is an entrance and exit hole with little meat damage. Accuracy is about 1" at 50 yards.

However, there is some powder fouling with partially unburnt powder in the bore.

The greatest challange you will face making subsonic loads will be getting a clean burn with a small powder charge. It become easier to achieve a clean burn when the bullet weight is heavy for caliber. For example, I can get a clean burn with a 290 grain cast bullet in 9.3 x 62 with .5 cc of Blue Dot.