I've always just played by knowing the key the song is in and learning it from there or from experience of knowing pretty much what scales can be played in what key and chord progression. I've never had any formal music training and am very eager to learn all I can to make me a better player. Some might call me a hack, but I've been hacking in bands and making money for quite a few years. I've played since I was a kid, but it's all been informal and whatever I picked up here and there.

I sat in with some guys recently when their bass player opted out. The guitar player would just yell over to me "4-5-5-7", etc. for the changes. For instance they did a set of songs all in G, then all in C, then a set all in A, etc.. I have to admit I was a bit lost at first but I mulled thru the sets okay, but not anything as perfect as I would have liked. I got the set list the day of the gig so I had about 3 hours to go over the songs in my head before the gig.

After reading the thread about song keys and theory I now better undestand or I think I do, what he was doing to let me know the chord changes and all. This is old rock, Texas style country (Pat Green, etc.), Bakersfield style (Dwight Yoakum, etc.) and western swing.

Am I way off base here on what the guitar player was doing or am I right? I plan to pick up some of the books and bass training materials and start learning everything the right way. I'm like the old farmer that drove his old truck around the farm for years, but when he had to get a license and take the driving test, his old ways wouldn't do.

Thanks for any assistance!

An old dog that still has some fight and bite in him.

Do a search for Nashville charts or number system. Sounds like the guitar player was doing verbally what the Nashville system does on papers.

Quickly the numbers are the scale degrees of the harmonized scale. So you need to know or be able to figure out the scale fast. Then know chords that come from harmonizing a scale. 1 = Ma, 2 = Mi, 3 = Mi, 4=Maj, 5=Dom7, 6=Mi, 7=Dim. So a 1, 6, 4, 5 in A would be Amaj, F#mi, Dma, E7.

A lot of people use the number system to memorize songs, especially if you back up lots of different singers. Makes changing keys real easy.

^ Everything Steve98 said. The Nashville Number System is a really easy on the spot song learning tool to know.

Here is a nifty site to help you bone up on some basic theory (chords, keys, scales, ear training) as well:
http://www.teoria.com/

Thanks SteveB98 and Ryco. You've been a big help. I've checked out multiple Nashville numbering systems sites per your advice and am picking up a lot of knowledge.