It's simple, heavy BBs concerve their energy longer. They need longer MED to be safe at hight fps, like for snipers.
I like your putty test DonP. Even if it's not scientific, it's still a good example of what happend.
Now trie this. With the same gun, fire a .25g BB at 350fps at 10fts of your target.
From the same gun, load .20g but get closer.
See at what distance, the .20g BB will have the same impact penetration as the .25g BB.
At 350fps, a .25g BB will have about a 1j impact at 10 fts. That would be the MED for this velocity and weight.
To validate the MED thing, if you can try a 450fps rifle, shooting .30g at 40fts of the target, you should also see similar penetration as the .25g, since it take 40fts for a .30g at 1.88j (450fps) to attain 1j of energy. That's it's MED.
All fps values are mesured with .20g.
Vérificateur d'âge: Terrebonne