im in the market to replace my barrel. i have no idea what twist rate my barrel is. i shoot whatever i can get. 55 gr to 69 nato. i dont shoot matches with this gun and dont hunt. just defense and target practice. what would be the best twist reate for me. middle of the road 1in8? is there a certain bullet weight for a certain twist.
55 to 69 for a 1 in 9 etc
thanks for any help jason
1/7 Twist rate is what I use I can shoot 55 grain up all the way to 77 smk.
1/7 is the only twist anyone needs. everybody has their own theories/thinking on these things, but the fact remains. 1/7s will stabilize 45gr HPs, all the way up to 80gr SMK.
awesome 1 in 7 it is thanks you guys are the best
I’ve got both and the 1/8’s are a J&T bull barrel and one is a Lilja. They are literal tack drivers with lots of the “surplus” ammo I have fired through them. Haven’t fired the Lilja barrel much as I just recieved it several days ago but the J&T barrel will shoot well under an inch.
What ever one you get a good deal on should be sufficient for your stated use.
WW
1/8 and 1/7 are the two best options. I would stay away from 1/9 twist rate.
C4
FACT. I’ve owned 1/7, 1/8, and 1/9. The 1/9s were subpar for various reasons. 1/8 was fine, but I stopped using the rifle for a long time and got rid of it. 1/7 will shoot anything you feed it, usually more accurately than you.
Anyone who tells you that 1/9 is fine, is just trying to justify to their self, that it was ok to purchase a subpar piece of kit.
If there were any real merit to the 1/9 twist rate, more high end makers would be using it.
We are talking about a 16" barrel, right?
1:7’’ would be ideal.
However, a 20’’ HBAR with a 1:9’’ twist, is pretty damn accurate with 55 gr. rounds.
BTW: Who makes 80 gr. SMK? Does the extra 3 gr. make a difference?
i use 1/9 and 1/7 for 99% of what i do. if you are going to replace a barrel then i would go with 1/7 as it give you the option of useing a wider range of ammo say 55gr- 77gr. if you choose to.
jmho
I agree with Grant. 1x8 and 1x7 are the only twist rates needed. 1x9 is just useless IMHO.
I like 1x8 for match barrels for maximum velocity with heavy 75-77gr rounds. 1x7 will work with them too but the push a little slower.
1x7 chrome-lined for my training/defensive guns.
The more twist the more accurate the heavier rounds will be. If you’re not sure what you’ll be shooting go 1/7, you can shoot pretty much any gr round you desire. 1/9 you’re limited at around 62gr.
My current rifle has a 1/9 hbar. But I shoot 62gr and nothing else through it. If I wanted to shoot a match round I wouldn’t have much success at accuracy at any kind of range.
So in closing, as everyone has pointed out, 1/7 
Correct me if I’m wrong, but I believe the length of the round is the determining factor for choosing twist. Yes, longer rounds are heavier, but I believe length is the key factor.
Yes it’s a projectile length issue.
64gr M856 tracer is longer than even 77gr MK262 and thus the 1x7 was needed in the M249/Minimi to stabilize the tracer round.
I also agree 1/7 and 1/8. I got a 1/8 and a 1/9. The 1/8 is much better, and eventually the upper with the 1/9 (things bought before knowing any better) will have a new upper with a 1/7 or 1/8.
I will shoot 75 grain TAP for defense. Haven’t had to defend myself yet, hopefully never, but the 1/9 does not like it (great for 55-62 grain stuff though.) I keep shooting up my 62 grain stuff and restocking with Hornady 75 grain TAP/Match ammo. Eventually that 1/9 will have to go just because of ammo load. As I get into reloading I will still be using something in the 75 grain range to mimic the match ammo.
Length of the projectile and velocity
1-7 .
only way to fly ! 
my somewhat/mutt/SP-1/clone … loves hornady 75 grainers,
a tack driver.
peabody
go with the 1:7
1x9 is just useless IMHO.
Would you clarify for me, sir, as a man of significantly more experience than I, what you precisely mean by “useless”.
Do you mean “useless” in the sense of “There’s nothing a 1/9 can’t do that a 1/7 or 1/8 can do just as well, if not better, and those twists support heavier bullet weights therefore when you have a choice, there’s no reason to choose 1/9”.
Or do you mean “useless” in the sense of “even when using bullets within a 1/9 barrel’s usable range (generally believed to be 55 to 69gr IIRC) there is something inherent about the 1/9 twist that compromises accuracy and/or performance”.
I ask because I am a member of the “I wound up with a Bushmaster because I got an amazing deal on it and went about fixing most of it’s problems, but I’m still tied to this 1/9” barrel" club (long name I know :p) and wish to know if I’m as okay with my BM with it’s proper bolt, extractor, receiver extension, staking, feedramps and lower parts kit as I believed (accepting that bullet weights over 69gr are inappropriate for my barrel).
My definition of useless which is the same as Dictionary.coms definition: [i]use·less
–adjective
- of no use; not serving the purpose or any purpose; unavailing or futile: It is useless to reason with him.
- without useful qualities; of no practical good: a useless person; a useless gadget.[/i]
.223 Rem and 5.56mm ammo I currently own:
LC M855 62gr
Prvi M855 62gr
Prvi 75gr MATCH
BH Mk262 Mod 1 77gr
BH red box 77gr MATCH
Hornady TAP 75gr
Hornady TAP 60gr
LC/Federal M856 tracer
BH 73gr Berger MATCH
Fed/American Eagle 55gr FMJ
Fiocchi 55gr
PMC Bronze 55gr
Guatamalan 55gr M192
Federal XM193
Prvi 62gr FMJ
BH 69gr MATCH
BH 68gr MATCH
Some kind of Frang, I can’t remember who it’s made by.
I own 3 SBRs, one 10.5", one 12.5" and one 14.5", two 16" midlength 3 gun rifles. All have either 1x7 or 1x8 twist. All but the two stainless barrelled 1x8 guns are shot suppressed from time to time. One of the 1x8 guns is my 3gun rifle and the other is my wifes Project Featherweight rifle (has perm. installed PWS FSC556 comp to make it a 16" barrel).
IMHO if I can’t use all the various types of ammo in the various types of guns I own and shoot them suppressed without worry of a baffle strike then I’d consider the barrel useless. Last year a friend of mine was shooting his 10.5" 1x9 twist SBR with his AAC M4-1000 attached, not paying attention he fired some red box BH 77gr MATCH ammo it in and after a few rounds had a nice hole is the side of his suppressors end baffle and his rifle got a hole lot ‘louder’. So he ended up having to get a replacement suppressor, AAC sold it to him for half of retail and he had to pay a new $200 tax on the new suppressor (new serial number). So he made roughly a $500 and a few months of NFA paperwork because he wasn’t paying attention because he had a useless barrel.
With all my ammo in all my guns I know for damn sure than any of the guns I have can and will stabilize any ammo be it .223 Rem or 5.56mm NATO ammo which is made that will fit into the magazines.
But the better question is why 1x9?
In theory it’s more accurate than 1x7 when using 50gr to about 69gr which is true for the long range stuff at Camp Perry this was true 15-20yrs ago when people used 68gr and 69gr a lot and used 1x9 twist barrels. But then came 73gr Bergers, 75gr Hornady and 77gr Sierra Matchkings and out came 1x7 and 1x8 twist barrels it does so well there that it dominates Hi-power rifle even kicking the asses of .308 and .30-06 in service rifle.
But here in the real world not the theory world I’ve seen many a 1x7 chrome lined barrel out shoot 1x9 barrels more than a few times. My BCM hammer forged (BFH) 14.5" chrome lined midlength shoots well under 1" using BH 77gr MATCH, BH Mk262 Mod 1 and Prvi 75gr match as well as BH 68gr Hornady and BH 69gr Sierra Matchkings. With PMC 55gr it’s shooting .58" 5 shot groups at 100yds.
Summary: If I can’t take any of my ammo and shoot it at 200, 300, 400 or 500yds and know damn sure it’ll stabilize the bullet and it’ll actually fly true out to those distances or that I load up a magazine with any ammo I have on hand and shoot my SBRs with an attached sound suppressor and fire away and not have to worry about baffle strikes…If I can’t do either of those things because the twist rate isn’t fast enough in my barrel then that barrel is useless.