The Korolev Crunch.

[N_Danger]

My policy on boosters is to place the wet COM on the decoupler. At burn out the COM is now below the decoupler, it fires and the booster peels away. 

I have had this cause a Korolev 'kiss' where the engine bells were meeting up behind the core stage. Sometimes not exploding.

[magnemoe]

I use loads of SRB an in my experience they tend to rotate 270 degree and impact each others. 
Now using liquid fuel boosters works better as center of mass is lower down, you want to limit the fuel in the separations however. 

Love the soyouz top from making history, have to use them on an Saturn 5 or SLS design because of rule of cool 

[StrandedonEarth]

I find that I do not need sepratrons, even with the type B nose cones wanting to push the nose in. I use the offset gizmo to slide the boosters down so the nozzle is below the nozzle of the core, with the decoupler being well forward of the center of the boosters, along with a pair of struts at the bottom. This way the decoupler pushes the top of the booster away from the core, while the bottoms only hit each other, if anything. The exploding boosters adds a nice kerbal flavor to the launch, and Kickbacks are so cheap they're not worth recovering anyways.

[ElJugador]

Ha, so this isn't just a quirk of my terrible booster engineering. Yep, this happens to me constantly especially on 1.25m flights, and on larger ships it can get very bad very fast if the boosters aren't far enough from the core.

Edited May 30, 2019 by ElJugador

[Geschosskopf]

 @NecroBones's wonderful Space-Y mods had radial decouplers with built-in Sepratrons.  Those would kick the boosters way out to the sides, but then the drag on the inside would bring them back together so they'd usually collide far behind the rest of the rocket.  I loved that and miss those mods.  Kept the part count down and also kept the rocket safe, plus provided gratuitous explosions during launch.

Before those mods and now after them, I use separate Sepratrons.

 

[Cavscout74]

3 minutes ago, Geschosskopf said:

 @NecroBones's wonderful Space-Y mods had radial decouplers with built-in Sepratrons.  Those would kick the boosters way out to the sides, but then the drag on the inside would bring them back together so they'd usually collide far behind the rest of the rocket.  I loved that and miss those mods.  Kept the part count down and also kept the rocket safe, plus provided gratuitous explosions during launch.

Before those mods and now after them, I use separate Sepratrons.

 

Haven't tried it after today's update/DLC but as of 1.7, SpaceY was still working good for me.  Some of @NecroBones's fuel tanks had issues in some of his other mods - specifically the radial tanks that were color coded to match the contents, but most everything else seems to work.

[MaxPeck]

19 hours ago, Geschosskopf said:

 @NecroBones's wonderful Space-Y mods had radial decouplers with built-in Sepratrons.  Those would kick the boosters way out to the sides, but then the drag on the inside would bring them back together so they'd usually collide far behind the rest of the rocket.  I loved that and miss those mods.  Kept the part count down and also kept the rocket safe, plus provided gratuitous explosions during launch.

Before those mods and now after them, I use separate Sepratrons.

 

The triple-packed aerodynamic separators are the bomb.  I use them with chutes triggered at separation, and with stage recovery, it saves me some funds and it's gratuitously satisfying to watch my boosters sail off into the distance and then get recovered.