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Page AR-15 » AR Discussions
AR Sponsor: bravocompany
Posted: 10/4/2004 8:54:18 AM EDT
how much better do you shoot with 1:9 than 1:8 with 55-62 grain?

I plan to shoot 100 yards 75% of the time and 300 yards 25%

so i plan on using 55-62 grain most of the time

which twist should i use?

does the twist matter that much at 55-62 grain

does Olympic arms offer SUM in 1:9

thaks for your help?
Link Posted: 10/4/2004 9:06:10 AM EDT
[#1]

how much better do you shoot with 1:9 than 1:8 with 55-62 grain?


Makes no difference as long as your bullets are of a weight that is stabilized by the twist rate.  For what you have stated, either will work just dandy.   IOW, if your shooting sucks, it will suck regardless of bullet weight or barrel rifling rate.


does the twist matter that much at 55-62 grain


Between 1 in 9 and 1 in 8, there will be no difference on target based on the bullet weights you have chosen.


which twist should i use?


1 in 8.  Because it will stabilize heavier, magazine length bullets (69 to 77 grains).  You say you don't want to use them now, but what about later?  With a 1 in 8, you can shoot bullets from 45 grains to the single round only 80 grain Sierra Match Kings w/o a problem.  A 1 in 9 will do OK with 69s, iffy with 75s, and will suck with 77s.  Not enough spin to stabilize them.

Bottom line, there is no downside and much upside to 1 in 8.
Link Posted: 10/4/2004 9:10:21 AM EDT
[#2]
cool thx
Link Posted: 10/4/2004 10:36:46 AM EDT
[#3]
I say 1/9
Link Posted: 10/4/2004 11:13:40 AM EDT
[#4]
why?
Link Posted: 10/4/2004 11:39:55 AM EDT
[#5]
i've always wanted a 1:8 or 1:7.7 chromelined barrel.... but they don't make'em
Link Posted: 10/4/2004 2:43:40 PM EDT
[#6]
btt
Link Posted: 10/4/2004 3:14:27 PM EDT
[#7]
+1 for what SWO_daddy says
Link Posted: 10/4/2004 4:51:54 PM EDT
[#8]
looks like the 1:9 is winning but the people picking 1:9 have no comments to back up their claim
Link Posted: 10/4/2004 4:55:04 PM EDT
[#9]
Deleated
Link Posted: 10/4/2004 4:56:02 PM EDT
[#10]
1/8, because you may someday want to shoot 77gr.
Link Posted: 10/4/2004 4:59:38 PM EDT
[#11]
Broad is the gate and wide is the path that leads to destruction........ If the majority is going to hell, are you going to follow them with a 1/9??
Link Posted: 10/4/2004 5:41:12 PM EDT
[#12]
im not picking 1:9 because they have not supplied any comments
Link Posted: 10/4/2004 7:47:03 PM EDT
[#13]
☺∞
Link Posted: 10/4/2004 8:00:34 PM EDT
[#14]
1/8 will NOT overtwist your bullets, so there is really no reason to get a 1/9.
Link Posted: 10/4/2004 10:52:19 PM EDT
[#15]
but some say 1:9 will shoot 55-62 grain better than a 1:8 i just wanna know how much better and what grain should i use to shoot out to 300 yards?
Link Posted: 10/5/2004 1:32:09 AM EDT
[#16]
One thing I haven't seen mentioned here yet is the relationship between velocity and twist.  Frankly, any bullet will stabilize in any rate of twist if pushed fast enough, but there's only so much powder you can cram into a .223 case and a point at which the bullet will go poof (the magical grey mist).  

The other thing not mentioned is that barrel length does have an effect on this mess as well...to a degree.  The shorter the barrel, the less time the bullet is being forced to spin by the rifling.  So, what will stabilize in a 20" barrel may not always stabilize in a 16" barrel of the same twist rate unless you up the velocity to compensate.  You can also go too long on a barrel to the point that all the powder is burnt prior to the bullet leaving the muzzle.  When this happens, typically you will see velocity drop and pressure go way up as any remaining barrel length is just holding all that pressure in with no additional energy (powder) to propel the bullet, thus resulting in drag.

The rule of thumb for twist is to be fast rather than risk not being fast enough.  Typically you would be looking at 1:10 or 1:12 twist barrel for the bullet weight specified (50-60gr) from a 22"+ barrel.  Considering the 16" barrel length provides less velocity and less rotational force applied to the bullet, a faster twist is mandated to stabilize the same weight bullets being pushed at the same velocity.  

This being the case, I'd definitely go with a 1:8 twist....especially if you'll be shooting factory loads.
Link Posted: 10/5/2004 1:49:58 AM EDT
[#17]
1/8 for future possibilities.

I say we start a poll to see if Ryu_Sekai's polls are effective.

1.  Yes

2.  No

3.  Don't know

4.  

R_S Poll
R_S Poll
R_S Poll
R_S Poll
R_S Poll
R_S Poll
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