Colt 614 & uppers?

[Beretta686]

I found a pretty nice price on a Colt 614 but have been reading some stuff about the size of the holes on the receiver limiting what uppers it can take. Can someone explain this to me?

And also tell me if I can put my Spike's .22 & M1S 7.62x39 (with my supressor & hi-cap mags my piggie friends won't know what hit 'em ) upper on it without much hassle?

Thanks

 

[Ridge_Runner_5]

Older Colts used out of spec everything. They changed fire control group pin sizes and takedown pin sizes, to make it as hard as possible for people to put NFA equipment in Colt rifles.