Hi, LeeroyJenkins - Sorry to hear you had difficulties with our brass CSST fitting. Make sure you're using our fitting on our pipe. You can't mix manufacturers. Yes, it is important that a clean cut is applied to the ss tubing. If there's a "shard" file it down. Cut back the yellow jacket 2 valleys of the CSST (about 1") and place the flange nut on the CSST pipe. Then insert the retainer ring in the last valley of the CSST. Be sure to squeeze it enough to stay in the valley, but not too tight as to oblong the part which can make the ss out of round. Then screw the 2 main brass pieces together. Continue to tighten until you cannot tighten any more. Along the way, you may feel that you "stripped" the fitting (it'll get easier) but that's simply the ss turning in on itself creating a nice smooth end which embeds in a hard fiber gasket. Generally, you'll see 1 thread or less in between the 2 brass pieces. As for "one time use", the fitting can be taken apart, a new gasket inserted, and reused. If you'd like to speak, please call our Technical Services Department at (661) 257-3923 x 1026 (Dave) or x 1010 (Jon) M-F 8a - 5p. Thanks.