I

[chrysanthemum]

If they stopped, they risked a potentially deadly confrontation with criminals.
Stopping, they risked a potentially ....
Is it possible to say If stopping ....

[bhaisahab]

If they stopped, they risked a potentially deadly confrontation with criminals.
Stopping, they risked a potentially ....
Is it possible to say If stopping ....

No.

[5jj]

Please give your thread a more helpful title than '!'

[chrysanthemum]

Please give your thread a more helpful title than '!'

I

[chrysanthemum]

Sorry. My keyboard doesn't work correctly. I typed adverb clause but i don't know what happened to it. Would you please tell me the reason why we can't use if here?

[Raymott]

Sorry. My keyboard doesn't work correctly. I typed adverb clause but i don't know what happened to it. Would you please tell me the reason why we can't use if here?

You can use "if", as in your first sentence. You can't use "If stopping ... " or "Stopping ...".
You can't say, Stopping, they risked ..." because they didn't stop.
You can say, "Stopping would place them at risk of ...."