Over the last few days I have been building 6 necks for a next batch of electrics.
I purchased 4 of Stewmac's #4401 carbon fiber re-rods a while back and more recently purchased 8 of LMI's GR4 carbon fiber re-rods.
4401 vs. GR4 consumer report:
The GR4s were not of consistent thickness. Out of the 8 GR4s 5 were between 0.133" and 0.138" thick which meant sanding them (very dirty job, toxic without a mask, and very easy to get nasty slivers). My main concern was that the GR4 were all slightly warped along the plane that would produce (unwanted) relief or back-bow betweeen 0.004" and 0.016".
The 4401s were all consistent length, thickness, were not warped, the downside being they're slightly more expensive (a quantity of 8 at $12.59 per vs. the GR4 at $10.30 per which can add up).
I mentioned these issues to LMI's customer service dept in an email. I received a reply stating LMI considers a variance of 5 thousandths to be well within acceptable tolerances for this material and typically do not get complaints about it. The (unwanted) relief issue was not addressed and I think .138" is more like .013" variance (doesnt fit the .125" channel).
Are there alternate sources for carbon fiber reinforcement rods out there?