Which twist rate works better for 30 cal

dick w. holliday · December 17, 2001, 07:02 PM

Which twist rate works best for 308----168 gr
which twist rate works best for 308-----147 gr.......

the answer may explain why my Austrian Kit FAL shoots 147 grainers better than the best match 168 grainers????????

thanks in advance----Dick

Charmedlyfe · December 17, 2001, 09:33 PM

The 168s should shoot OK in the 1-in-11 or 1-in-11.25 barrels that are the norm for FALs. I've got a 1-in-10 on my Mauser, and it handles everything very well. My FAL with the 1-in-11.25 is best with 150-ish grain bullets, but will handle the 168s. It doesn't like 175s, while the 1-in-10 bolt gun is awesome with them.

I don't have the Greenhill formula saved anymore, but if I remember right, the break between 1-in-10 and 1-in-11 was around 160gr. Best of luck!

Target Shooter · December 19, 2001, 12:12 AM

Greenhill Formula:

150 X Bullet Diameter (squared) divided by the length of the bullet in inches. The answer will be the optimum twist rate for that particular bullet.

Sample for 155g Sierra Palma Match bullet:
150X.308(squared)=.094864 divided by 1.130"=12.59 twist rate.

TS

dick w. holliday · December 19, 2001, 07:13 AM

Cyphering ain't one of my strong points but i'll give it a try---thanks..Dick

December 17, 2001, 07:02 PM	#1
dick w. holliday Senior Member Join Date: January 13, 2001 Location: NC Posts: 589	Which twist rate works better for 30 cal Which twist rate works best for 308----168 gr which twist rate works best for 308-----147 gr....... the answer may explain why my Austrian Kit FAL shoots 147 grainers better than the best match 168 grainers???????? thanks in advance----Dick

December 17, 2001, 09:33 PM	#2
Charmedlyfe Junior member Join Date: October 11, 2000 Location: SC Posts: 799	The 168s should shoot OK in the 1-in-11 or 1-in-11.25 barrels that are the norm for FALs. I've got a 1-in-10 on my Mauser, and it handles everything very well. My FAL with the 1-in-11.25 is best with 150-ish grain bullets, but will handle the 168s. It doesn't like 175s, while the 1-in-10 bolt gun is awesome with them. I don't have the Greenhill formula saved anymore, but if I remember right, the break between 1-in-10 and 1-in-11 was around 160gr. Best of luck!

December 19, 2001, 12:12 AM	#3
Target Shooter Senior Member Join Date: May 19, 2000 Posts: 176	Greenhill Formula: 150 X Bullet Diameter (squared) divided by the length of the bullet in inches. The answer will be the optimum twist rate for that particular bullet. Sample for 155g Sierra Palma Match bullet: 150X.308(squared)=.094864 divided by 1.130"=12.59 twist rate. TS

December 19, 2001, 07:13 AM	#4
dick w. holliday Senior Member Join Date: January 13, 2001 Location: NC Posts: 589	Cyphering ain't one of my strong points but i'll give it a try---thanks..Dick