My uncle recently purchased a DPMS 'Lo-pro' AR15 and is interested in putting iron sights on it. It has the railed gas block. Anyway, he wants a carry handle rear sight, I've asked him and that's non-negotiable, he also prefers a fixed front sight, but will settle for a folder if that's all I can find. He knows nothing about it and has pretty much turned the project over to me. Is it a simple job to change the railed gas block to an A2 post? I wouldn't be too worried about attempting it but his has a bull barrel and I have no idea of the diameter. That would be preferred if its the easy way out. But if not, can someone recommend a front sight on the same plane as the carry handle? Thanks.