what causes the bbs to be chopped up in half?

after doing some maintenance on my cylinders it started to get chopped bbs.

Few things to check:

1) Ensure that your nozzle is done up tightly
2) Your hop barrel key (the big silver bit on the end of the barrel) is fully forward
3) Your magazines are lubed - this is probably the culprit especialy if you are using a fast battery 2400 mah + etc as the BB's cant be forced into the chamber quick enough - hence chopy chopy!!!

To eliminate completely, purchase part BR-021 from Systema - its their barrel key and its about £10 and this will never happen again. You will also find that you will get a better seal with the 'O' ring in the barrel which will give you better range.

i will soon post a topic about that...its not just this things what can cause chopping or double feed....i did some modifications to hop-up chamber etc...and it works awesome now...before chopping and double feed was present every 3rd shot...

soon guys soon:)