I hear people saying they switched to loops because of nock pinch. What does this cause and why does it really matter? I just switched to a loop on my new bow but I never had trouble shooting off the string.

Take a short axle to axle bow and draw it back with your fingers and you'll get a good idea what nock pinch is. Now imagine trying to shoot a grapefruit out of a potato cannon and you'll get a good idea of the problems it causes.

Hope I wasn't too technical for ya.

So how can you tell if you are experiencing it if you shoot with a release below the nock.

Nock wear.

Opinions vary sometimes on just exactly how snug a nock should be on your string.

You can nock an arrow on your string and then gently pull the arrow off the string directly foward as if it were being shot. This is where opinions vary but in my case when I pull the arrow I dont want the string to come forward any more or any less than an inch. If it pulls off too easy and your string barely moves you need to replace your nocks (not always caused by pinch , they do wear out also). I would be more worried about nock wear than pinch as long as you have a properly setup nock system. If shooting off the string I prefer to have two nock sets along with the rubber cushion.
If my string moves too much forward when I check for wear I'll gently open the nock a very little bit at a time until I get my desired fit.

What is your axle to axle length and your draw length?

When i first started with my WB i couldn't get any consistent grouping so i took it off and put on my NAP 3000 and with the prong rest every time i drew back the arrow was lifting up off the prongs.I opened up the string loop until the arrow was doing what it should on the draw,put the bisquit back on and have been a happy camper ever since--i didn't notice what was happening with the bisquit on because it contains the arrow so it can't come off the rest.Just a heads-up if you have a bisquit or other type of containment rest.

Nock an arrow, pull back to full draw. Now let up on the bow without releasing the arrow. Inspect the arrow nock at the string. Did the nock start to come off the string. If it did, you have nock pinch.