[tlm225]

Most manufacturers tell you not to shoot reloads for liability reasons. The glock, the 40 caliber mostly, has developed a reputation for "Kaboom's", usually case head separations. Many explanations are given. No case support at the six o'clock position in the chamber, the high pressure of the round, hot loads etc... I have had a KB in my first glock 40, a model 22 which I believe was caused by a fellow officers hot reload (I later found out that his load had also KB'd in a Sig). In my case the case separated leaving the forward portion of the case lodged in the chamber, the magazine blew out and the extractor went into low earth orbit.
With that being said I have reloaded for the glock .40 for about 8 years with no problem. I use only jacketed bullets, stay in the middle range of the recommeded loads and stick with the slower powders from the load charts. Thousands of rounds later I've had no exciting moments. I'm sure that some one with both more knowledge and experience will come along and fill in whatever gaps I've left. Good luck with your G-27. I've had mine for about 7 years and am happy with it.