Even though I posted here in 2011, I completely forgot such a thread existed.
This weekend I'll visit a club and maybe even shoot some arrows.

Also, what is GPP? FOC?
Yeah it's a bit quiet, haha. I don't usually talk archery unless I've bought something new and fancy, although I think I even forgot to post my newest longbow here. :lol: Shame!
GPP is Grains per Pound, it's a measure of arrow weight (in grains) per pound of draw weight. So, if you were shooting a 300-grain arrow out of a 50lb bow, you would be shooting 6GPP. It's considered important for a couple of reasons: first is that the lighter your arrow, the closer your bow is to being effectively dry-fired since there is less arrow mass to absorb the shock of firing. Folks generally recommend at least 5GPP to avoid bow damage, although I can't say for sure how accurate that rule-of-thumb is. Second is hunters (especially trad hunters) like to have heavier arrows so they have greater inertia, in theory that will help them penetrate better if they glance off a bone, rather than just wounding the creature. Trad hunters tend to shoot for around 10GPP, but as with anything there's many different opinions on it.
FOC is "forward of center", which is a measure of where the center of balance of the arrow is. Trad hunters tend to like the balance to be biased more towards the point end of the arrow, so GPP/FOC are influenced by both arrow weight and point weight. A light arrow with a heavy point will give a high FOC, and vice-versa. FOC is very opinion-oriented and I'm not sure if anyone has done any real testing on how it affects arrow penetration.