I've got a PTR-91 and got a Magpul PRS stock for it. I pulled it apart and it had one of the long, enhanced buffers in it. I quickly discovered that the long buffer and the PRS stock don't play well with each other. I looked at drilling it out but that seems a stretch. I'd rather use the correct length and be done with it. Which is the best standard length buffer? It looks like there are several to choose from. Or doesn't it matter?