1-8 Twist .vs 1-9 Twist

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OK boys, I just ordered a Model 52 Cooper in a 6.5x284 and the twist is 1-8. My question to the bench rest guru's or any reloader who know twist rate better than me, "what difference is there between the two twists regarding bullet selection?" Some reloading manuals have a 1-8 twist and others have 1-9 twist and I want to use the Nosler 125 grain partition for hunting. Speak to me.
 
1-8" is the standard 6.5mm barrel twist

1-8" barrel twist is what is required to stabilize long 6.5mm bullets as 140gr very low drag target bullets and heavy 154-160gr large game bullets.
With a 1-9" you're limited to 140gr hunting bullets while with a 1-8" barrel twist allows you to use all hunting and target bullets.

You definitively made the right choice.

Alex
 
There will be no noticeable difference between the two, with any bullet weight you will use.
Just shoot it, with whatever bullets you want.
 
My Cooper in 6.5x284 loves the 120 grain Nosler balistic tip hunting bullets in front of 59 grains of Reloader 25 for 3050 fps. Prints 1/2" groups and seems to kill stuff pretty well.
 
The theory is to use the slowest twist possuble that will stabilize your bullet. This is because the bullet is spinning at about 180,000 RPM and any jacket irregularities are amplified, as are any slight misalignment of chamber to bore. If only using 125 grain, the slowest twist would have been better, but, as pointed out, the faster twist offers a wider range of bullet weight, actually length. There's a few formulas for this, and software programmes, with the former usually quite conservative.
 
It really depends on the bullet lenght. I have a 9" twist that shoots 140's but they are Flat based...have not tried the long VLD bullets. the 160 gr. RN are really not that long and I would not be surprised if they also shot ok. Of course you could just take all the measurements and do the math...I think its the greenhill formula.
 
If you re not planning on shooting the long VLD's or the heavier hunting bullets then go with the slower twist.

If you even think you might want to try those bullets, get the 1:8.
 
CyaN1de said:
If you re not planning on shooting the long VLD's or the heavier hunting bullets then go with the slower twist.

If you even think you might want to try those bullets, get the 1:8.
Click to expand...

My intentions are to reload and shoot the medium 125 and 130 grain bullets from Nosler. This firearm and cartridge is solely for whitetail/mule deer and hoping to have get the maximum out of the reloads for volocity and accuracy.

In your comment, your stated that the slower twist of 1-9 is better for the longer heavier bullets? Therefore, the 1-8 would be better for other bullet weights/lenghts?
 
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