Weak Powder?

[victor1979]

I had an eight twist barrel put on my 22-250 and I bought a Berger book some 77 grain bullets and a can of AA4350. I loaded some up and went to the range and it shot well at 100 meters. I took it out and according to the drop the bullets were only going 2700 fps. The groups at 450m were tall and skinny like the bullets were going different speeds. I tried some VV550 and wow the bullets are really dropping a lot less and grouping much better at range! According to my shooter app the speed of the bullet matches what the book says almost exactly. I have no idea whats going on here at all can anyone shine some light on this. According to the book the AA4350 and VV550 should be really close speed wise with this combination.

 

[Boomer]

Apparently that bullet performs better in your rifle with N550, so don't over think the problem. If it shoots better with N550, use N550. Unless you shoot over a chronograph, you won't know for sure whats going on. Perhaps the brass you used with AA4350 is less uniform, perhaps Berger didn't calculate the BC of that bullet correctly, making the velocity appear worse than it really was, perhaps your powder scale isn't repeatable to within +/- .1 of a grain. Once the can of worms is opened, its tough to get them all back in.

 

[TIPPY91]

i shoot 80gr vld berger out my 22-250 it has a 7.5 twist barrel length is 27inch i'm getting 3150fps using 32.7grs of n550 with lapua brass. i'm really happy with n550