I am not a skilled or experienced modder but as one of my first attempts I modded my Nerf AccuTrooper (Alpha Trooper) with a 5kg spring, a plunger rod guide and an stiffer spring for the plunger tube retainer. I also bored out the AR completely. The blaster went from shooting ~68 FPS to ~100 FPS. The blaster cycles darts perfectly and everything feels fine. About half of my shots are dead on but the other have shoot very far to the left even at 10-15 feet. This is with Nerf Accustrike darts and AF waffle darts. Elite darts are worse obviously.

Could my new spring have caused this issue? What about drilling out the air restrictor? What factors contribute to the accuracy of a spring nerf Dart blaster?

I'd like to get into modding but this first attempt is disheartening. Any help would be greatly appreciated.