Hold Down?
Just shoot it by squeezing them off gently. If you try to fight it, you'll surely shoot the ground at 15 to 25 yards in front of you and never learn to shoot correctly, or with any decent accuracy. If you can't squeeze them off and let it roll, try a different caliber that doesn't have as much bite.
When shooting a revolver (especially single action) or a single shot pistol, you shouldn't (or don't need to) hold the gun very tight at all. Use a very light grip on it, despite the caliber. What do I mean by "light"? Light enough that someone can easily knock the gun out of your hand if they were to try.
The only guns that might require a firmer grip (but still light) would be some autos that might not cycle correctly when "limp wristing" them.