Pet Loads 308 1 in 10" twist barrel, 168g Amax and IMR4064 - Care to share anyone?

SKScanuck

SKScanuck

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Pet Loads 308 1 in 10" twist barrel, 168g Amax and IMR4064 - Care to share anyone?

I am just trying out my new Savage 16ITH in 308 with a 1 in 10" twist 308 and have found the load my son and I developed for his M700 in 308 with a 26" 1 in 12 twist is not working for me. I caught on to this when I got about a 6 inch drop from 100 to 200 yards.

Anyhow, I was using 41.5-41.6g of IMR4064 and would prefer to stick with the powder as I got lots of it. I am thinking of trying some .5 grain increases to the max load abut if anyone cares to share one that works for them, I might limit my range.

Cheers
 
That powder and bullet are good choices. No need to change them.

Find a loading manual or two, and see what it says. I looked at Hodgdon's online data, it has data for the (very similar) Sierra 168MK, indicating a start load of 41.5 grains IMR 4964 giving 2518fps and 43,800PSI, and a max load of 45.9 grains IMR 4064 giving 2766fps and 58,800PSI.

Let's assume your load in your gun is developing 2525fps (it could easily be anywhere from 2425fps to 2625fps). Run this through a ballistics program (I like JBM) and I see a calculated drop of 4.9" from 100y to 200y. This is pretty close to what you've observed. So the results you are seeing are basically matching what would be expected.

If you have a chronograph or are able to borrow one, that can oftentimes speed up your load development.

It would be worth working up in 0.5 grain increments. Observe all the usual precautions (every loading manual has a writeup on working up loads and watching for pressure signs). Often, you'll see accuracy improve as you go to hotter loads.
 
every gun, every barrel, every batch of powder and every lot of bullets is different.

seat your bullets as close to the lands as you can and work your powder loads up in .3-.5 grain increments from book minimum to find what works best. no such thing as a 1-recipe-for-all-308's or any other gun.
 
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