Twist Rate for 100-1000 yds. Muzzle Crown?

[N2rockets]

Hi guys

I am interested in putting together a Remmy 700 .308 with a McMillian A4 stock. I shoot between 100 and 1000 yards most commonly. I am wondering what twist rate is best for those ranges. I know you can get 1-12, 1-11.25, 1-10 and stuff, I dont know what each is best for though.

I don't reload at all so I dont know what types of loads and powders mean, so I am not really taking that into consideration right now, in the future maybe.

I am also wondering what the front crown does to the bullet trajectory. I would like to put a muzzle break on the rifle, or have it threaded at least for future silencer access. What does this mean for bullet path?

Thanks in advance for your help! I appologize for the Noobishness

 

[OutlawTen5]

Re: Twist Rate for 100-1000 yds. Muzzle Crown?

1-11.25

 

[Hateca]

Re: Twist Rate for 100-1000 yds. Muzzle Crown?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: n2rockets</div><div class="ubbcode-body">Hi guys

I am interested in putting together a Remmy 700 .308 with a McMillian A4 stock. I shoot between 100 and 1000 yards most commonly. I am wondering what twist rate is best for those ranges. I know you can get 1-12, 1-11.25, 1-10 and stuff, I dont know what each is best for though.

I don't reload at all so I dont know what types of loads and powders mean, so I am not really taking that into consideration right now, in the future maybe.</div></div>

Depends on the bullet but 1-11.25 seems to be the norm with .308.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: n2rockets</div><div class="ubbcode-body">I am also wondering what the front crown does to the bullet trajectory. I would like to put a muzzle break on the rifle, or have it threaded at least for future silencer access. What does this mean for bullet path?</div></div>

None that you would ever notice. As long as the crown is cut correctly you would be hard pressed to see any difference. Cutting the barrel for a brake may dictate the type of crown depending on the brake. Cutting for a suppressor for later on you would want a thread protector if there is no brake to help protect that crown.

 

[SAS_Sniper]

Re: Twist Rate for 100-1000 yds. Muzzle Crown?

1/11,25

 

[XLR]

Re: Twist Rate for 100-1000 yds. Muzzle Crown?

The twist rate will depend on the bullets you would like to shoot. Twist rate is proportional to bullet length, not weight. Although most heavier bullets are longer, some solids are lighter yet longer. Optimum twist rate for the bullets you would like to shoot con be found with this formula:

Define the Variables:
T = Twist rate in 1 turn per inches.
L = Bullet length in inches.
V = Muzzle Velocity
D = Diameter of the bore grooves in inches.
Constant = 3.5

Find the optimum twist rate from velocity, bore size and bullet length:
T= ( 3.5 * SqRt( V ) * D² ) ÷ L

(TMT Enterprises, 2007)

Different muzzle crowns really dont effect accuracy; however, some crown cuts offer more protection for the "tactical" shooter than others.

I personally have had good luck with the 1:10 because I like to run high BC bullets for long range.

 

[sobrbiker883]

Re: Twist Rate for 100-1000 yds. Muzzle Crown?

As bullet technology (or popularity) increases, higher BC's bullets will be more readily available and prominent. Higher BC is usually longer. As your distance increases, the need for high BC increases.
At least that's my thinking and why I went with a 1:10 when I rebarreld my 308.

I'm trying a recessed 90* crown right now, but I think I will be having my muzzle recut threaded and thread protector done in the near future for the can I want in the long run. The recessed 90* crown is working well (at least within the parameters of my inconsistent shooting ability).