The elongation of cotton is measured as the percent of fiber stretching prior to reaching the maximum force during a bundle tenacity measurement. For HVI testing, the fiber specimen gage length is 1/8 inch and observed elongation readings are in the range of 5 to 15 percent. Therefore, accurate measurements require a rigid test fixture and extremely precise position sensing. In this report we describe some hardware design modifications and position sensing methods used to measure bundle elongation. HVI strength and elongation measurements were made on a series of cotton samples and compared with Stelometer results using 1/8 gage Presley clamps. Methods to calibrate elongation measurements with cotton and adjust observed results for fiber crimp, slippage and hardware deflections are discussed.