After reading several posts and suggestions on certain stocks on certain rifles--I have to ask:

What does a short stock(collapsed all the way down) gain you on an M4, 16, or 20"?

Do you gain a better sight picture baing closer to the rear sight? OR  Is it just for quicker shouldering of the rifle in CQB's?

Are the 'shorty/entry' stocks a good middle ground?

Thanks

Stocks are a personal preference type of thing, but they can make a big difference. The less you have to move your neck, head, body to get into a comfortable shooting position the less fatiguing it will be. That means you can shoot more accurately for longer periods when you are comfortable.

Do you gain a better sight picture baing closer to the rear sight? OR Is it just for quicker shouldering of the rifle in CQB's?

Both. Adjustable stocks let you adjust the LOP (Length of Pull) to give you the best position regardless of changes in the gear you are wearing. Some people don't have the need to adjust this, some people don't like the cheeck weld they get on an adjustable stock, etc, etc.

There are lots of reasons to have an adjustable stock, and there are a lot of reasons to have a fixed stock. It will take some time, but eventually you will find a setup that you like.

Body armor and gear take up space.  Adjustment is needed to maintain your cheek weld and sight picture while wearing gear like this.

Shorty/entry stocks are just about as short as you can get.  The fixed Sully stock is good middle ground for a fixed stock.