Advice on .22lr Ar15 upper reciever length

[GuiltySpark]

If someone has an AR15 (14.5" barrel) and is looking to purchase a .22LR upper receiver what length would you all suggest between 7.5", 10.5" and 14.5"?

Chances are it won't be used past 50 meters.

It would be for simple target shooting and possibly CBQ style shoots but not very much.

 

[little_airwolf]

Lighter then better. However my guess is most will say try to match your AR to train.

 

[yohann160]

14.5"

 

[GuiltySpark]

Would the ballistics/accuracy be that different between the 10 and 14" over something as short as 50 meters?