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Amax decision

09 Oct 2012
@ 06:18 pm (GMT)

Matt Reid

Hi all,

Just wondering if I could have some input regarding which weight amax is optimal in .308. I have tried the 178s, had good accuracy then went to 168s as I had the impression I needed more vel/less drop. Now I am a little torn. Shooting range sub 750m, twist 1 in 10, game- red/sika/goat.

Matt

Replies

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09 Oct 2012
@ 11:04 pm (GMT)

Jim Moseley

Re: Amax decision
Can you list the MV's for each bullet? The twist rate of your barrel may also determine which bullet is best suited for accuracy. Nathan stated that the Amax will still expand with a speed as low as 1400 fps. When you run the numbers then you see which bullet will give you the max range as long as it gives you the best accuracy. Accuracy will trump speed any day. Let us know.
10 Oct 2012
@ 12:58 am (GMT)

Matt Reid

Re: Amax decision
Approx 2600 vs 2700. Running the figures, drop and windage doesn't yield a great difference. I haven't probably persevered enough with the 168 to give them a fair chance.
10 Oct 2012
@ 03:21 pm (GMT)

Nathan Foster

Re: Amax decision
Hi Matt, I am just in the middle of a semi custom build, rifle will be similar to yours, M700, 20" barrel. The rifle is expected to be used at bush ranges on Red and Sika deer, but be able to perform at long ranges of up to 600-700 yards if need be.

Due to both bush and long range work combined with the typical body weights of Red deer, I have recommended the 178gr A-Max to the client. The slightly greater weight and SD of the 178gr bullet does have a very slight edge over the 168 grain bullet regarding penetration after fragmentation. This increase in penetration is usually only noticed at closer ranges.

As Jim pointed out, it is important to take the 1400fps velocity parameter into consideration. You will find that to some extent, any loss in muzzle velocity is made up for with an increase in BC which ultimately evens everything out at long ranges. However it is still important to run the numbers.

Your current load is producing 2636fps. With the 178gr A-Max, MV will be approximately 2536fps. At 2536fps, the 178gr A-Max breaks 1400fps at 760 yards. Your current 168gr load breaks 1400fps at 790 yards.

10 Oct 2012
@ 03:38 pm (GMT)

Matt Reid

Re: Amax decision
Thanks Nathan. My most recent load with the 168s was clipping along closer to 2700 but either way will be seeing about a 100fps drop with the change in projectile I imagine.

The scenario you describe is quite similar to my own, in that I will be on ocassion looking to shoot at bush ranges. The increase in sectional density sounds like a good thing also. Looks like heading back to the 178s may be the way to go. Now just need to find some!

Cheers,

Matt
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