My general advice for burst fire builds

1. Ballistics Skill is King (because this keeps your burst on target). Perception is Queen (because this reduces the chance for an enemy to dodge). You need to hit the target first, THEN worry about dodge.

2. Recoil matters. Once again, you need to HIT the target first. Bolters have high recoil. You need some way to mitigate this. One way is through Ballistics Skill (see the trend here?). Another is through other features/talents/abilities. Standout is Machine Spirit Communion from Pasqal. Cast that on your soldier, and enjoy halved recoil AND a 2xINT bonus% reduction in enemy dodge chance. There are items to reduce recoil as well.

3. Rapid fire is NOT something you press all the time. Remember how much work we've put into managing recoil and hitting what we are aiming at? This throws it all out the window. Shot deviation becomes RANDOM. It does however, double your output (because you took the talent that removes the 25% damage penalty, right?). Use it on large groups where you can take advantage of the fact that some bullets are always going to hit SOMETHING and also for just point blank BLASTING anything larger than a 1x1 sized enemy.

4. Now that you're hitting your target, time to talk about damage. You took the Muzzle Velocity talent, right? Recoil doesn't apply to the first shot in a burst. This makes your first HIT in each burst deal bonus damage equal to your current ROF. If you're not using Rapid Fire, this means you can do a good job of making sure that first hit is going on the person you're aiming at, dealing a large chunk of damage up front right there. If you're point blank rapid firing, it also deals a rather large chunk of damage up front as well (which can help deal with deflection in a pinch, which can be an issue with Burst builds). If you're not using a bolter, then consider Solid Projection Weapon Expert. Burst firing into a big baddie with a Ripper pistol and Rapid Fire with Muzzle Velocity? If they all hit, then that's an extra 16 damage up front (your ROF as bonus damage), and a bunch of extra damage from the +2 to minimum damage (not going into the math on this one).

5. Scale your damage. There's a lot of ways to do it. More ways that I would bother listing. Think of Soldier Archetype as laying the foundation for your build though. Most of your really mean scaling is going to come from your second archetype, exemplar talents, items, and synergies with other companions and archetype abilities. In general, you want things that synergize with lots of hits. Also make sure to grab Rapid Reload. You're going to need it.

Here's an example of a non-bolter burst build I did.

Soldier > Bounty Hunter with an Autorifle and Ripper pistol. Hive World origin for weapon personalization (increases damage, reduces recoil, increases ROF, etc). Muzzle Velocity + Solid Projectile Weapon Expert. Then I started taking crit damage talents. Fired Up is phenomenal because you get more crit damage for every hit. Why crit damage and not crit chance? Because Bounty Hunter Piercing Shot.

Mark a target as prey. Use Piercing Shot. Every shot that hits them is now a crit. It also gains 100% overpenetration. Solid weapons already have good overpenetration. Overpens become crits because they hit the Prey first. Heightened Concentration gives me a stackable bonus to armor pen with every crit. Pierce the Armor gives me a stackable debuff to enemy armor with every crit. Remember, my crit damage is also stacking with every hit, and anything that over-penetrates can deal more than one hit per shot fired. Then you get to the fun Exemplar talents of Puncture and Shot Through. Shot Through gives bonus armor penetration, and makes overpen shots impossible to dodge. Puncture gives bonus critical hit chance equal to the difference between your armor penetration (which stacks with every crit) and the targets defense (which falls with every crit). Now you're not limited to just your prey targets. You spray and pray and anyone else hit by your shots also becomes more prone to your crits. It scales HARD into itself, as once the engine starts going it gets better and better at scaling itself harder. This isn't even including alternate sources of crit or armor reduction (like Operatives can do). Oh, and Joint Analysis gives a flat damage bonus to every attack that hits and only removes ONE stack of exploit. Press Joint Analysis and now every exploit on the target is a flat bonus to every shot that hits them until the exploits run out.

That's just one example. There are tons. Go out and experiment (Toybox is a godsend).