Theres an interesting article that i came across online from the USA. Hardairmagazine measured and weighed a full tin of H&N FTT 5.3headed pellets - .22,s
Of the 503! pellets in the tin most were 5.55mm plus and quite a lot 5.6mm. I bought a digital vernier caliper and did the same tests myself.
They were 100% correct in their findings.
Kev