GT Series

The GT Series carries two entries on our books, the M6.4K-GT and the GT Series putter itself, and both point to the same design lineage from MacGregor by Bobby Grace. thegolfwire.com described the line as milled from a single block of 60-61 aircraft grade aluminum, with an elongated trapezoidal head shape, a deep CG design, and an annealed Beryllium Copper face insert. The same publication credited the line with exceptionally high MOI, calling it a high resistance to twisting, and noted an engraved centerline paired with dual silver bands for alignment.

thegolfwire.com's reporting on the M6.4K-GT ties the model to tour performance, noting it was used by the 2005 PGA Tour Championship winner and calling that finish a dominating performance. The site's coverage of the broader GT Series struck the same note on feel, praising amazing feel and feedback and pointing again to the Beryllium Copper insert as the reason. High MOI engineering shows up as a recurring theme across the coverage of the line, mentioned both in connection with the M6.4K-GT's tour pedigree and in the general notes on the GT Series.

Read together, the record shows a line built around one core idea, a deep-CG, high-MOI aluminum head paired with a soft Beryllium Copper face, carried across at least two named releases without much variation in the story reviewers told about it.