300 Win Mag ????????

[dbblung]

A friend decided to try loading some 180 gr Nosler Accubond for his 300 Win Mag. He loaded them with the same powder charge(70 gr IMR 4350), WW cases, primers and seating depth as the Sirrocco 180 gr he was currently using. At the range the Noslers shot a very tight group, actually smaller than the Sirrocco's did, BUT they were exactly 3.5" low(at 100 yrds) with the Accubonds. The bullets are both boattail design, but the Sirroccos are much more thinner tapered in design. Is there that big a velocity difference or is the difference in the bullet design the major reason for the BIG difference in how different the two bullets shoot. Please help me out, it has both of us scratcing our heads!

[Ridge Runner]

has to do with pressures and bearing surfaces, the thinner tip of the scirroco means it has less length digging into the rifleing causing them to shoot higher, nothin to worry about just adjust the scope and go from there. almost always 2 different bullets of the same weight shoot to a different point of impact, thats what the knobs on the scope are for.
RR

[halcon]

Different ballistic coefficience could account for the difference . If you want to see a big difference try a round nose bullet as opposed to a spitzer

[SJAdventures]

Like said, adjust your scope and don't worry about it.

[dbblung]

Thanks for the replies fellas. My friend is corcerned that if the Accubonds shoot that much lower at 100 yards than the Sirocco's do. He thinks they don't shoot as flat and there will be even more noticeable drop at longer ranges with the Accubonds. We do plan to take the chrono. out within the week and compare the velocities of the two. I think he is making more out of it than need be!

[Scott Gags]

Originally Posted by dbblung

Thanks for the replies fellas. My friend is corcerned that if the Accubonds shoot that much lower at 100 yards than the Sirocco's do. He thinks they don't shoot as flat and there will be even more noticeable drop at longer ranges with the Accubonds. We do plan to take the chrono. out within the week and compare the velocities of the two. I think he is making more out of it than need be!

His change in point of impact is not a function of the velocity or the ballistic coefficient of the bullets. The barrel actually resonates slightly as the bullet travels toward the muzzle. The point of impact is a function of the barrels position at the point the bullet exits the muzzle.

My 30-06 shoots the 168 Nosler BT @ 3010fps one inch left of the bullseye. The200 grain accubonds at 2713 Fps are approx 5 inches high and the 180 accubonds at 2820 FPS are 8 inches high.

Just adjust your scope to the new point of impact and all is well.