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Old February 25, 2013, 08:38 AM   #1
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165 grains make that big of a difference?

My .308 has a 1/10 twist and it really seems that it doesn't like the 165 grain SST's.

It does seem to like the 178 grain HPBT.

Could 13 grains make that big of a difference?

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Old February 25, 2013, 08:41 AM   #2
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It's possible. However, it is just as likely that it doesn't like that particular bullet/powder combination.
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Old February 25, 2013, 09:47 AM   #3
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I'm voting with Doyle. Recently I was working up loads in one of my rifles for a specific bullet that I wanted to use. Until I changed to a slower powder than I had been using, it would not group acceptably. With the new powder I got great groups. The only change to get me from unhappy to happy was the powder. And I'm not specifically saying that going to a slower powder is the answer to your problem. I'm just suggesting that Doyle has a very good point. Try another powder, or ask the folks on the forum what powder works for them in a similar rifle. That might get you the answer you want.
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Old February 25, 2013, 09:55 AM   #4
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Re: 165 grains make that big of a difference?

Thanks....I am using IMR 4895

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Old February 25, 2013, 02:53 PM   #5
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Bullet weight probably isn't the reason for the difference.

My .308 Savage 10 FP shoots 168 grain SMKs and Nosler CCs really well with
N140 & H4895 at around 2600-2650 fps at 2.815 to 2.820 COAL.
It shoots N140 a bit better (average of about 0.015 in accuracy with the best loads with the same bullet types and weights) than H4895 but I chalk that up to better powder metering due to the finer grains of N140.

It also shoots 150 grain SMKs and 175 grain SMKs well with the 150 grain loads a bit more accurate.

The 25 grain bullet difference between the 150 and 175 didn't make a whole lot of difference but the accuracy with each bullet and powder combination was sensitive to the seating depth/velocity combination.

It doesn't seem to like factory or hand loaded 165 grain bullets as well but the bullet shape was different so I probably didn't have the hand loads seated at the right depth.
In my most recent tests, I didn't have great luck with 165 grain Nosler Partitions but the 165 grain Nosler Accubonds shot pretty well. Partition bullets are flat based and Accubonds are boat tailed.

I concluded that the weight wasn't really the problem, the bullet shape was. More precisely, the difference was the amount of bullet body touching the rifling. That might have changed the harmonics.

Unfortunately, I didn't try enough different seating depths to find a really good node with any of them that would challenge the Sierra Match Kings or the Nosler Custom Competition bullets.

You may need to experiment a bit with COAL and velocity to see if you can find a node with those 165 grain bullets. Or try a different 165 grain bullet with a different shape and you might find it shoots really well.
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