Joined:
Apr 2026
Posts:
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VA, USA
Posted: 4/6/2026 7:42:42 AM EDT
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Folks, what could explain this experience with my .308 Win on a LH Stiller .308 TAC action firing the below handloads: 1.44.0 gr. of Varget powder (new), measured on A&D FX-120i, to accuracy of 0.00 grain 2.Federal 210M match primers 3.Sierra 175 TMK bullets 4.Lapua brass 5.Neck tension: a.Fired brass: I anneal after every single firing using the AMP of New Zealand b.For new Lapua brass (unfired), before bullet seating I run the unlubed neck only thru a Redding sizer die (standard expander ball, not a custom neck diameter) c.Neck tension, verified using Forster Neck Tension Gage (NTG), of 0.0030” – 0.0035” 6.COAL 2.810” 7.Lothar Walther 20-inch LW-50 stainless barrel, match reamer chambered, broken in, nearly 1,900 rounds through it, starting with clean barrel, firing ~ 25 rounds 8.AWC .308 cal suppressor, perfectly fitted, direct thread install 9.OAT 59F 10.Dry gun, no rain, no wind 11.Velocity measured by Garmin Zero Doppler, positioned per tech order a.Velocity mean of 2,618 fps MV b.~ 1 out of every 10 rounds recorded low end speed of ~2,575 fps MV c.Max speed = 2,651 fps MV d.Extreme velocity spread = 75 fps e.Std Dev = 30 fps That’s a huge drop velocity drop. What could possibly cause that? |
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if it's the gun, it's 60% chance the barrel needs a serious cleaning and inspection. 308 normally isn't shot out that soon, but sometimes it can be or maybe it just has a lot of copper build up or something. In my experience with some calibers, i can go 1500 rounds and keep SDs tight, but with others, 300 rounds and i have to clean to get my SDs back to single digits. very much a YMMV situation. 30% the firing pin is dragging. disassemble the bolt, spray off all the lube from the firing pin and spring with break cleaner or something, then apply a small amount of light oil, no grease. reassemble and repeat test. make sure there's nothing foreign in the firing pin hole. make sure no pitting, and no erosion of pin or weird marks on primers. (add grease back if appropriate after test) 10% chance there's a trigger issue. eg sear engagement not set properly, so it drags and changes FP energy you covered all the usual suspects on the ammo side. my recommendation, since we're talking 308win here, is to grab a box of premium match ammo (fed gm match 168g) and use that to benchmark. if it's consistent, or not, then you'll have a pretty good idea whether to focus on your rifle or ammo. |
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Originally Posted By taliv: If you’re shooting 100 yards Yes, SD's of 30 are not great....but not necessarily "bad" either. Even if the OP is shooting 600yds, plugging in the velocities from highest to lowest (ES 75) changes POI at target 5" which is less than 1 MOA Assuming the OP has a 1/2 MOA rifle in theory it should be capable of 8" groups @ 600- shooter skill dependant of course. Even Fed GM Match typically has SD's in the low 20's. There's lots of posting of chrono results on Accurate Shooter and youtube videos to back those numbers. Mass production often has +/- over .1 gr powder variance. You brought up good points to check on the rifle to eliminate causes for wide velocity. The OP is using accurate measuring and consistent neck tension. We can assume it is not a loading technique issue. However, it could also be the OP needs to go back and find a load that burns more efficiently to reduce the SD's. |
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i agree with all that. people have different expectations. mine would be that since i think F-class matches are great practice for wind reading and marksmanship (prior to running around on barricades) I'd expect a rifle to be capable of at least holding the 10 ring and ideally the x-ring vertically at 600. yeah, 8" practical targets at that distance is a reasonable expectation. however, i imagine the OP is thinking, if that's all the accuracy i'm getting, why did I spend thousands on precision powder dispensers and annealers etc, when I could just throw powder and get those ES? |
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Compared to the older balance beam scale (resolution of 0.1 gr) those new powder dispesers (A&D FX-120i) are capable of 0.02 gr accuracy. That's literally a single kernal of Varget. However, case fill (volume) of powder affects burn efficiency dramatically. Load data books give ranges anywhere from 95% to sometimes 101% fill "C" (Compressed). I don't use Varget so I can't comment if the load is near max or not. It's possible that the OP saw good groups with this load and assumed success. However, it may need some fine tuning - up or down a few tenths of a grain to find the combo of accuracy and lower ES/SD's. |
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Originally Posted By HighpowerRifleBrony: What is the SD after omitting the slow outlier? |
"Technique isn't something that can be taught. It's something you find on your own." - Bunta Fujiwara
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Originally Posted By smoothy8500: I wonder why the OP hasn't come back to give us feedback on suggestions or questions asked. Originally Posted By smoothy8500: Originally Posted By dodpilot100: Folks, what could explain this experience I wonder why the OP hasn't come back to give us feedback on suggestions or questions asked. Notice it was OP’s fist post. |
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