I go to bank. Hit RB, it switches to back pack. I press A on a weapon, it moves to bank, I press RB again and nothing. Hitting RB does not switch me back to my back pack.
What am I doing wrong?
You don't actually need to hit RB again you can just move over to your backpack with the joystick.
All you need to do is open the safe, move over to your backpack and click on let's say the babymaker (in your backpack) for this example it will then switch you over to the bank and ask you to place it in an empty slot.
Now move back over to your backpack and click on a different weapon that you want to store. Your babymaker will remain in your backpack and the other gun you clicked on should go into your bank.
Rinse and repeat, just always click on a gun you want to keep in your inventory first. Should work as long as you are doing it on the bank and not the secret stash.
Hope that works, makes it so much nicer than having to swap between characters just to have space to keep my guns.
How many items can you store before you compromise performance?
Nobody knows. A poster on reddit says that his friend actively holds 150+ items in his bank, and I do remember a post detailing that at X many items, the scroll function starts failing... but I'm not sure.
Does seem to work. But either way, you need copies of your rare gear on mules chars anyway. I use 1 char for each type of gun, smg, AR's, SR's, pistols, ect..
This is to cut down the guns you hoard on 1 character, and most likely wont even need to use this glitch.
Of course splitting your items is convenient! Unfortunately, some people (myself included) are discontent with the amount of guns we can hoard with one character. Why not have one character for relics and class mods? Well, even then you cannot hold them all with one character without this glitch.
Also, if you want backup copies of your guns, it's pretty easy to duplicate items split-screen. Make an alternate xbox account for your new save, a bank character. Give them items, and let the game save (you can pause and press B to auto-save, since their character is then kicked out). Then, have their character drop the items. Then, take their controller and log the profile out. Voila, duping. Both characters should have the items.