The Tippmann Arms 12" handguard is a great upgrade to your M4-22. The M-LOK design allows mounting of bipods, grips, lights, lasers and optics.
Free float handguards are known to improve accuracy. The accuracy of the free-floating handguard comes from the fact that the handguard doesn’t touch the barrel – it is mounted directly to the upper receiver. This allows the barrel to “float” and gives better harmonics, resulting in slightly increased accuracy.
Accuracy difference is especially evident when using grips or bipods. When you rest a rifle on a bipod that is attached to the barrel, or a drop-in handguard, the bipod will create force that can slightly warp the barrel. This small amount of warping can provide fairly significant accuracy issues on the range. But with a free-float handguard, you can put all kinds of force on the handguard and it won't affect the barrel whatsoever.