From what I’ve read, the two springs on the trigger are actually different and should not be switched. Are there reduced power disco springs for the 3-round burst triggers, or would I be fine dropping any normal reduced power disconnector springs in there?

The Colt factory 3rd burst fire control groups I have purchased have come with two different spring weight disco springs.

There is a black colored spring that controls the primary/semi disconnector on the left side of the trigger and that interfaces with the selector and a silver colored spring on the right that runs the burst disconnector on the right side of the trigger and that interfaces with the burst cam on the hammer.

The black spring on the left side controlling the primary/semi disconnector is stronger and is similar to (if not identical to) a standard AR15 disconnector spring in terms of strength.

The silver colored disconnector spring that runs the burst disconnector on the right seems to be maybe 50% the strength of black disco spring on the left.

I don't work at Colt and didn't sleep in a holiday inn express last night but my guess is that they have two different disco spring weights to try and account for the fact that the trigger pull can vary depending upon the burst cam location and/or the heavier than normal trigger pull in burst mode.

On the M16 3rd burst arrangement there are  two disco springs as mentioned above.   The  black primary/semi disco spring is compressed whenever the selector is set to burst and the real tail of the primary/semi disco engages the selector.  So when you pull the trigger the primary/semi black colored disco spring is compressed as the tail of the primary/semi disco is compressed against the selector.   This is a similar arrangement as any standard full auto S-S-A M16.

However, on the burst arrangement there is a second burst disconnector with its own silver colored disconnector spring.  The burst disconnector doesnt interface with the selector, so there is no disco spring tension relationship to the selector location.   However, the burst disconnector's spring does get preloaded in two different weights depending upon the burst cam orientation.

The M16 burst cam has a total of "6" cutouts, four that are shallow and two that are deep.   These are paired two shallow + one deep to make up a single 3rd burst cycle.  As the cam rotates around and the burst disconnector moves from shallow to shallow to deep cutout it allows the burst disconnector to ride forward and catch the hammer, forcing you to release the trigger to reset the whole operation.

Since the disconnector cam is not resetting and continues to rotate independently of selector setting, technically the burst cam and burst disco are "along for the ride" when the selector is in the semi-auto position.  The net result is that you will get two semi-auto trigger pull weights that are heavier when the burst disconnector is rocked back by the burst cam when the trigger is pull and then one lighter trigger pull when the burst disconnector is allowed to actuate forward into the deeper notch on the burst cam which doesnt compress the silver burst disco spring.

Here is a good animation on how it works.

https://www.youtube.com/watch?v=cxwPEL8winI

Colt probably lightened the burst disco spring for two reasons.

1. Try and even out the semi-auto trigger pull depending upon the burst cam orientation.
2. Try and lighten the heavier than normal trigger pull when the selector is set to burst where you have to compress two disco spring, the primary/semi disco on the left that is being compressed against the selector barrel and the burst disco than is being compressed against the burst cam wheel.

This seems to be unique to Colt as I have had some DPMS burst disco springs where the left and right side are the same part number.  I suspect its not critical for function and is just an attempt by the Colt designers to make the best of a not ideal trigger pull setup.

In terms of a RLL conversion it doesnt really matter what springs are used from a trigger pull perspective as the burst disco arm is cut off and the burst cam removed in the conversion so the only disco spring that is compressed during the trigger pull is the primary/semi disco on the left that interfaces with the selector.

However, I always suggest folks run the lightest possible disco spring on the right (former burst) disconnector as possible.  Either a aftermarket reduced power disco spring from Wolff or the reduced power silver burst disco spring if they bought an OEM Colt kit to modify (vs. a DPMS)

The lighter the burst disco spring the less stress that is put on the link to pull it back and release the hammer.

Hope this helps.