Glock magazine legalities

[Sport]

I was recently talking to a fellow Glock 19
owner and he told me all six of his Glock
brand ten round magazines actually held
eleven rounds once the spring had been
broken in. I was skeptical until he
showed me. He says he made no modifications
to any of the magazines. Today I tried
stuffing eleven rounds into two of my ten
rounders. It takes some effort, but it can
be done. Incidently, the other Glock owner
says he has had no failures caused by the
increased capacity.

I remember reading somewhere that there may
be a legal question about doing this to
post ban low caps, but I don't recall if it
was referring to non-modified magazines.

My assumption is this practice is not good
for the magazine, but does anyone know if it
is also not "good" for the magazine owner?

 

[swampgator]

My father got issued a SIG 220 with 3 seven round magazines. Not being marked with a capacity everyone began stuffing rounds in til they wouldn't fit anymore (new magazines), dad managed to get nine in.

Weapon wouldn't chamber any. So it probably isn't a good idea to try to stuff eleven rounds in a ten round magazine.