How old is a RRA LAR-15 with the serial number
CM 61XXX? Is there anything better or worse for newer/older models as well?

Thanks.

I have one that is approximately 9 years old, and it's serial number is CM179XXX, although the first 1 is pretty faint. I suspect that the one you are looking at may be CM161XXX. I definitely don't have a space between the letters CM and the numerals.

But, mine is brand new in the box. In fact, the lower hasn't been assembled yet. I got a complete upper, and a lower with lower parts kit. I'm just saying this to point out that chronological years mean very little to nothing in regards to the useful life of a firearm.

As to whether newer/older are better or worse, I can't say, but I think they're pretty much the same now as they were 9 years ago.