![]() Cartridges were held at temperature for at least 90 minutes before being fired in the rifle. Temperature Adjustment and Velocity Measurements: Cartridge temperatures were established by double bagging loaded cartridges in plastic sandwich bags and placing them in containers of water at: 1) 1 C (ice water) 2) ice cooled tap water (11 C) in a large mouth Yeti bottle 3) tap water (25 C) in a large volume water cooler and 4) warm tap water (37 C) in a 36 oz. Powder charge was measured with a RCBS Charge Master 1500 for this first test and changed to a less variable method in the second test. The N140 load was set at a lower velocity performance level because I was uncertain of its temperature sensitivity at higher temperatures, and I didn't want to reach over pressure levels. The IMR 4166 load used was the same grain weight value as the IMR 4064 load since the two powders have been reported to have comparable performance. The IMR 4064 load was calculated using QuickLoad V.3.9 (2015 database) to achieve similar velocity using a Berger 200 gr hybrid bullet for the bullet value and default temperature setting of 70 F. 308 Winchester bolt action rifle with 30 inch Bartlein 5R 1:10 barrel Lapua Palma brass (4X reloaded following neck resizing at 0.002 tension) CCI BR4 primer Berger 200.20X Hybrid bullets loaded at 3.02 inches COAL (0.02" off lands)Ī Varget load for the cartridge that gave 0.39 MOA accuracy performance at 200 yards (2583 FPS at 71 degrees Fahrenheit) was selected. ![]() Powders and Loads Tested in Lapua case with 200 grain bullet :ġ. Data from the first test would be used to conduct a more detailed second test with promising powders. The initial tests only used 3 replicates shots per powder per temperature. The first test was a wide-range survey of 4 powder temperature-velocity responses. The temperatures I used in the tests cover the range that I experience in F-TR rifle matches in North Central Florida (34☏ to 102☏). The purpose of the studies was to identify a powder or powders that may have temperature insensitivity comparable to that of Varget. This website reports results of temperature-velocity tests that I ran with Varget and 3 other rifle powders reported to perform well by competitive F-TR shooters. Unfortunately, this popularity and high demand coupled with limited importation of powder produced in Australia and marketed as Varget in the United States has resulted in recurring shortages to U.S. Varget's positive reputation for being relatively insensitive to temperature-dependent velocity changes puts it in great demand. Like many other F-TR shooters, I have been using Varget powder for bullets in the 175 to 208 grain range. Tests for a Possible Varget Powder Replacement in a. ![]()
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