I only did it because my favorite style of AR rifles are the 20" M16/C7 types. As for if it makes the gun better than its original Sport II configuration? Probably. The barrel is chrome lined with heat shield hand guards. A bayonet will also actually work now. The 16" barrel guns the barrel is too long after the gas block and not enough blade is sticking out to actually do anything. If you didn't like the long rifle length AR's though then there really isn't a reason for you to do it yourself.
There's much to be said about the original 20" barrel configuration.
Primarily for reliability. The dwell time with a rifle length gas system and barrel is the perfect balance of reliability and impulse/recoil dampening.
The full length barrel gives optimal velocity for shooting out to distance and maintaining high velocity out to 300m effective.
The 14.5" barrel and carbine gas system is over gassed making it reliable but very hard on the system and recoil. It's the only other properly developed config aside from 20" original config.
All other combinations get a little wacky but that's a whole other topic.
The A1 config to me was the pinnacle of AR15 for balance, accuracy, reliability, recoil, weight and effect to distance. Plus having one of the longest sight radiuses of any battle rifle. Theyve been chasing their own tail ever since.
Especially with the 55gr projectiles. Projo leaving a 20" muzzle at damn near 3,300 + feet per second!
Not many people have ever fired one in the old school original config. It's a dream to shoot and handle. You can fire it one hand standing and still keep it on target all day.
Nice in any case though!
