starting to hate reloading

[foreign]

thanks for all the information guys. im not to sure how to culculate the rpms for the bullet but i seem to be getting good clean holes through the targets.
i forgot to mention that they are leaving at 2850fps. i thought that would have been plenty fast enough to stabalize them.
i will hopefully try some amax of a similar weight and get them to work. though that will not be for a long time since in moving to the USA after my next 3 months of work until august.
im just going to have to start shooting bunnies with the 7mm wsm

 

[foreign]

i looked on the net and the .223 bullets should be doing 252,000rpm so that should work. the .308 is a 1 in 10 twist so i should be able to load whatever bullet i want.

 

[lynxpilot]

Have you tried a set without the silencer?

 

[Trickymissfit]

thanks for all the information guys. im not to sure how to culculate the rpms for the bullet but i seem to be getting good clean holes through the targets.
i forgot to mention that they are leaving at 2850fps. i thought that would have been plenty fast enough to stabalize them.
i will hopefully try some amax of a similar weight and get them to work. though that will not be for a long time since in moving to the USA after my next 3 months of work until august.
im just going to have to start shooting bunnies with the 7mm wsm

I think I'd try something lighter and a little shorter in length. In other words a little less ballistic coefficent. I had trouble getting the Amx bullets to stabalize when compaired to another bullet of equale weight. But I'd think a 70 grain bullet would work just fine (don't have a Hornaday catalog close by).

to figure the rpm of a bullet in flight you multiply the velocity by a factor number. But you also need to plot the flight of the bullet to get the velocity at certain shooting distances. Here's a chart I have calculated for several twist rates:
1:15 = .80
1:14 = .857
1:12 = 1.00
1:11 = 1.09 2850 x 60 x 1.33 = 227430 rpm at the muzzle
1:10 = 1.20
1:9 = 1.33
1:8 = 1.50
1:7.5= 1.60

gary

 

[Trickymissfit]

i looked on the net and the .223 bullets should be doing 252,000rpm so that should work. the .308 is a 1 in 10 twist so i should be able to load whatever bullet i want.

that's at the muzzle, but you need to plot the bullet's flight
gary

 

[foreign]

hey gary at 400m bullet should be doing around 2073fps. so 2073x60x1.5 gives me 186570rpm. does that sound right and enough got the 80 berger?

 

[rhouser]

I shoot an 1:8 AR platform and moved back to the 75gr AMAX. I know my 8 twist will shoot the 80's but, 75's seem to just lay in better for me.

I know this is obvious, but, have you checked for parallex at 365? If you are parallexed for 100 and shooting 365, that could give you 5 inches if you arn't just "dead behind" your glass. Just my 2 cents. rc

 

[Trickymissfit]

hey gary at 400m bullet should be doing around 2073fps. so 2073x60x1.5 gives me 186570rpm. does that sound right and enough got the 80 berger?

sounds good to me. At 186K rpm you getting on the ragged edge of stability with a VLD bullet (remember the 180K figure Walt quoted). It's close, but the velocity is there (have you actually chronographed the load?). The only load data I have for the 80 grain Berger is right out of the AA manual, and the max they show is just under 2700 fps (muzzle velocity) using a 26" barrel. The 80 grain Sierra is good for another 100fps, but not a VLD. At 400 meters you don't really need a VLD. I think I'd give the Sierras a try if you just have to use the 80 grain bullets, or better yet drop down to the 64 grain Berger.
gary