Maturity is certainly the key, and there is no set chronological age at which this becomes a factor. I know people in their 40's with the maturity levels of a 3-year-old, and I know some teens with the maturity levels of a wise middle-ager.
I guess it just has to be a matter of individual judgement.
The reading problem is not necessarily indicative of maturity, however. It may be more indicative of bad teachers who don't take the time to reach out to every student. When I was 9, I could read at a level above my age, but then, I always loved to read. I got my first gun at 6.5, and was hunting (with Dad) by age 8.
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Shoot straight & make big holes, regards, Richard at
The Shottist's Center