A quick history. I have a new rifle and scope that I have recently sighted in and got to a point where I thought I could fine tune some loads. The rifle is a 700 CDL in 7mm mag with a Zeiss Conquest scope. I used Speer spitzer psp 160's to sight the rifle in(I sighted in for about 3 inches high at 100 yards), I used a medium load of 62 gr of RL 22 for this task. I plan on using 160 gr Accubonds for hunting this year, so today I took out my first batch of loads for testing. The AB's shot nearly 2" higher with 63 gr of RL 22. I expected a little bit better flight from the AB's with better aerodynamics and 1 gr of powder more, but it seemed to me that 2 inches was a bit much. I guess the question is, does anybody find that a bit much or is that fairly close to what I should expect from AB's?

quote:

I should expect from AB's?

There is no way to predict the point of impact when you change loads.It might move up,down or to one side or a combination.Contrary to what many people think,a higher point of impact at 100 yards does not mean higher velocity or a higher ballistic co-efficient.

stubblejumper is correct. The difference in impact is due to different barrel vibrations.

My personal observation has been that more powerful loads will impact the paper lower, most of the time. The secret is finding a bullet/powder combo that hits to the same approximate point of aim with charges varying as much as a couple grains. Then you know that you are in the sweet spot for that rifle. I had a Tikka 3006 that would shoot 150's 165's and 180's into the same 2 inch circle at 100 yards. Last week I was working up loads in my 7mm wsm with RL22 and as usual the more powerful loads were getting lower and lower until I hit the sweet spot and put 3 groups into about 3/4 of an inch within 1.5 grains of differential, and 140 Interlocks. Hope the Partitions do as well when they arrive.

First time out of the hatch I think you're lucky that they landed only a few inches apart. Most of the time different loads won't print like that for all of the reasons stated above. That's doubly true for you since the accubond is of boat tail design and the Speer isn't. I have fought this battle before, and some guns just don't like boat tail bullets(I'm talking minute of deer here, not MOA) and results were unsatisfactory.

Try that at distances greater than 500 yards and see what the boat tail bullets will do. Their payoff is definitely on the far side of point blank range.

Cudos on the 160s, you have chosen, IMHO anyway, the single best bullet weight for the 7m/m Remington magnum.

StubbleJ is right. I find this bbl. harmonics issue more a problem w/ lt. wt. bbl. than heavy wt. You are lucky if your rifle shoots diff. bullets into the same POI.

Thanks for the replies. Guess, I'll change my approach to trying new loads. I'll build at least 3 or 4 extra bullets each time I make a change, just for the purpose of sighting in the scope for each different round. Thx again

Mike, IME heavier/slower bullets usually strike lower than lighter bullets at higher velocity. The Accubond's, however, might be an exception!

Last Sunday I was sighting-in 168 TSX's in my 30-06. For grins I brought along my 180 AB loads as well... they printed 1.2 (ish) inches higher than the 168's. In this gun, lighter/faster have always, in the past, printed higher while heavier/slower have printed lower... not the 180 Accubond's. Go figure.

I initially sighted in with the 160 Speer's because they are a bit cheaper than the AB's. But when I went to check some AB loads they were about 2-3 inches higher. I thought that it may be due to the bullet design, but from the responses it appears that it may be other causes. It's not a big deal, now that I know that there can be such a huge difference I will just adjust accordingly.