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Showing results for tags 'Loading bench Report'.
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Loading Bench Report: First we'll go over the results of my brief bit of load development. I had data from my previous load experience with the 7mm-08. I develope my base data from "Quickload", a very reliable software program for predicting internal ballistics. It can be uncanny in its predictions of Mv/pressure. As with "book data" one needs to back off starting loads if unfamiliar with the case/bullet/powder combo or the particular weapon that is being loaded for the 1st time around. There is a thread about this particular weapon here. http://huntingny.com/forums/topic/26124-savage-axis-ii-im-impressed-and-im-pretty-picky/ I had found in the past that "high energy" powders such as Vihtavouri N500 series will achieve up to 100 fps better Mv at similar pressure compared to the various old standbys like IMR, Hodgdon, etc conventional powders. More recently, Alliant RL17 has been developed for the new breed of "short magnums" & it will perform similar to Vv N550 in medium case volume/bore ratio cartridges. I had nearly a pound of Vv N550 on hand, so that was the powder I used. My previous 2900 fps load for my M700 7mm-08 was 47gr of Vv N550 behind a 140gr Nosler BT. Since the chamber of the Savage AXIS-II was considerably tighter than the M700 I backed off 2gr. I felt this was a good starting point since the magazine length of the Savage allowed me to seat the bullets out .050" farther to get them close to the rifling lands, thus somewhat mitigating the higher expected chamber pressure from the tight chamber. "QuickLoad" predicted about 2825 fps @ 48K chamber pressure W/the 139gr SST @ 2.850" OAL. As usual, Vv N550 reached a bit more Mv than predicted & the bullets were leaving the barrel in the 2875 fps range W/ some hitting just a bit over 2900. I felt I had room for just a bit more powder so I bumped it up .5gr. Mv icreased only slightly, but it became more consistant. Quickload predicted about 2860 fps @ 50K chamber pressure. Actual Mv indicated chamber pressure closer to 60K so this was close to SAMMI max spec & still perfectly safe in a bolt action rifle of modern design. There where no physical signs of high pessure. No hard bolt lift, ejector pin marks on the case head or severely flattened primers. Below are the results. 5 Shot String Data: High Mv: 2928 fps Low Mv: 2901 fps Av Mv: 2912 fps Ex spread: 26.2 fps Std dev: 11.4 fps Av dev: 8 fps This is some of the best consistancy I have ever seen. I decided to load up the 75 remaining 139gr SSTs for a range session.