.308 155gr Scenars kicking my ass

well went out today and focused, focused focused. noticeable drop in accuracy when seated back to 2.85. after much ####ing about and kicking sand, my last 10 shots were solid in the ring hits on Eds Vbulls. lets see what happens during zeroing tomorrow. I've got data from 2 different sources, Knights and Sierra. Plus I have two sets of data from Sierra. one is just the bullet drop, the other is Milirad values, strangely enough they don't match up (IE divide the centimeter drop by the first digit of the yardarge, so for 600 it tells me the bullet will drop 254.93. so divide by 6 and you get 42.5 or 4.25 Mill, which in my S&B would either be 4.2 or 4.3, yet when asked to calculate Mils the program says 3.9 Mil, and Knights says 4.4). hmmmmmmm
 
Odd result with the Sierra ballistic program; I suspect you should use the Knights. Using JBM for a 155 Lapua at 2850fps at std. conditions (sea level, 59F, etc), for point of impact = point of aim at 100m, and a 1.5" sight-over-boreline height, I get 103.6" of drop at 600m, which is 263cm of drop at 600m, or 4.38 mils (2.63 metres / 0.600 km = 4.3833 millirad). I would certainly go with 4.3 (or 4.2 or 4.4) mils of rise relative to 100m, rather than 3.9.

FYI, a number of years ago I found a load combo for Lapua 155s that can be shot very accurately at shot and mid range (300, 500, 600), with a great deal of bullet jump. I shot a mild starting load that gave 2750-ish fps from a 30" barrel, and it was superbly accurate from 100y to 600y; I ended up using it as my F-Class competition loading for a number of years. I accidentally discovered (loose locking screw on my WIlson seater die ;-) that the bullet jump could be anywhere from .030" off the lands to .150" off the lands, and still land in the V-bull (!). This load had horrible SDs (25+-ish), and at long range it shot like you might expect (horribly - elevations of 2.7+ minutes, impossible to hold 15 shots in the bull). But at 300, 500 and 600, I could shoot scores that would win F-Class matches in 1997-2002 (e.g. 12-shot 600 yard groups that were 0.4 minutes high by 1.0 minutes wide).
 
Still back at twist. I think the 155's will generally be better with a 1 in 14 twist, while the 168's will be better with a 1 in 12. Sometimes the difference can be quite small in my experience. It's not that the bullets are bad or that one can't shoot good groups with 155's in a slower twist. It's just that the consistency and levels of accuracy being demanded will likely be more easily achieved with the right bullet for the twist. My last 308 showed this so clearly. The barrel had a 1 in 14 twist and would shoot 155's all day. The 168's would shoot groups that would impress everyone but someone shooting in a sniper match. It was a good gun after all. But the group average was just a little poorer than with the 155's and every once in awhile there would be a flyer that would move the group to 3/4 of an inch (truth). Naturally the 3/4 inch group would look like a disaster. The difference wasn't at all like my present 6 BR that sprays anything over 90 grains like a shotgun. Hope the match goes well.
 
I shoot these in a factory 700p, although its not the same rifle I find my groups open up a bit if I seat them longer than 2.800. Also use mostly varget, but RL 15 has worked for me as well.
 
I tried the 155gr Scenars in my 700-5r this morning and was quite disappointed.I just can't get then close enough to the lands and have enough bullet in the neck,or have them short enough to fit the magazine.Groups were not nearly as good as with the Matchkings.I guess that I will be putting the scenars in the EE,and going back to the Matchkings.
 
well it's all over and done. the 155's ended up shooting quite well. but I grabbed two boxes of 167 Scenars off the prize table and will be playing with them next. I intend to have my load sorted long long before next years match. I just think the heavier bullets leave my gun happier.
so now I need pet loads for Varget and 167's......
 
You must log in or register to reply here.
Back
Top Bottom