To add to what fuzzy said: Read other posts on the board.
There are about 2 or 3 other posts that talk in depth about which chambers fit the ASR and at least one that I can think of off the top of my head that is specifically about the ASR. For the most part Ronin and I have been the ones answering most of the questions about this gun since we have been doing the most tinkering on it, and for the last few weeks it has become rather tedious to continually tell people that you need the L96 chamber for the ASR. However, I would never want someone to wander away from the forum for lack of help or because of a poor first impression, so I will say it again: you need the L96 chamber for the ASR, ideally you get one that will take an AEG barrel i.e. the PDI, and get a good barrel to go with it. There area number of active threads on all of these topics and a number of them asking about the ASR specifically. So please go through the recent posts and use the search feature.
There are about 2 or 3 other posts that talk in depth about which chambers fit the ASR and at least one that I can think of off the top of my head that is specifically about the ASR. For the most part Ronin and I have been the ones answering most of the questions about this gun since we have been doing the most tinkering on it, and for the last few weeks it has become rather tedious to continually tell people that you need the L96 chamber for the ASR. However, I would never want someone to wander away from the forum for lack of help or because of a poor first impression, so I will say it again: you need the L96 chamber for the ASR, ideally you get one that will take an AEG barrel i.e. the PDI, and get a good barrel to go with it. There area number of active threads on all of these topics and a number of them asking about the ASR specifically. So please go through the recent posts and use the search feature.