I just took a look at the pipe that was originally delivered with the system and here is a pic of the slot it came with. The new pipe's slot is a third that size at most. About the thickness of a bandsaw blade actually. Other than that Peter...these new pipes are PERFECT and as I said, widening the slot was 30 seconds work. Had I done that before I stripped the stock bolt...it really would have been no problem.
If I were British I would describe the new pipes as some part of a dogs anatomy, or perhaps an insects knees or something...but as a Yank...I'll just say....they fit far better than George Bush as president.
Bill