223 twist rates question

[Matt52]

I have a question about twist rates on 223 rifles. Most come with a 1in9 twist for lighter bullets but you need 1in8 or 1in7 for heavier bullets. Do the faster twist still shoot lighter bullets well and if so why dont rifles in 223 come with faster twists than 1in9?

 

[nipprdog]

but you need 1in8 or 1in7 for heavier bullets. than 1in9?

Define heavier. 1/9 shoots 68gr just fine.

 

[Matt52]

Define heavier. 1/9 shoots 68gr just fine.

The big ones 77 on up

 

[chuddly]

faster twist rates can spin bullets apart that are to light (from what im told). The heavier bullets need spun faster to stabilize. a 1:7 twist can go up to around 80 gr and down to about 52 gr. If you go with a 1:9 twist you can go to the lowest weight in 223 on up to around 62 gr. it really comes down to what you are wanting to do with the gun and what bullets you plan on shooting. Neither is BETTER than the other. Just one fits distance shooting better and the other is better for short distance and cheaper plinking.

 

[kawtech87]

1-7 is the Mil-spec If Im not mistaken It will stabilize anything 55gr and up just fine. The only thing it will not stabilize is super light varmint ammo.

1-9 is commercial spec. It will stabilize anything upto and inculding 55gr but not much heavier.

1-8 is a compromise that some think gives an advantage, and maybe with some rounds thats true but for most EDC rifle work 1-9 will be absolutely fine.

I like 1-7 just bc I dont shoot anything lighter than 55gr ammo and milsurp is 75gr (I think) and cheaper when it can be found.

 

[sgreen3]

Here is an article that may help a little bit

223 Rem + 223 AI Cartridge Guide

 

[chuddly]

1-7 is the Mil-spec If Im not mistaken It will stabilize anything 55gr and up just fine. The only thing it will not stabilize is super light varmint ammo. its not mil-spec. the first "AR" style rifle was 1:14 then they went 1:12 then 1:9 which are still carried to this day and is the standard issue rifle. The reason for the higher twist rate for for the heavy bullets but its by no means "standard mil-spec". It will go down to about as about 52 gr or even a bit lighter but thats about your limit.

1-9 is commercial spec. It will stabilize anything upto and inculding 55gr but not much heavier. It will go up into the 60's pretty well

1-8 is a compromise that some think gives an advantage, and maybe with some rounds thats true but for most EDC rifle work 1-9 will be absolutely fine.

I like 1-7 just bc I dont shoot anything lighter than 55gr ammo and milsurp is 75gr (I think) and cheaper when it can be found.

lilsurp comes in all different weights. The "standard" if there is one is 55 gr. They also have 62 and 68 gr so take your choice.

All kinds of wrong info here to be had

 

[phylodog]

Lots and lots out there to read about twist rate vs bullet weight. Lots and lots of internet lore and myth. The reality is every rifle is different and the capabilities of that rifle will differ from the next one off of the line.

Here is my Remington SPS with a 1 in 9 twist barrel cut at 18".

Here is a 5 shot group of Federal Gold Medal Match 77gr SMKs at 100 yds

Here is another

Had a couple educated folks mention that it may or may not maintain bullet stabilization much past 100yds. Notice I said may or may not rather than won't. I've shot it at 820 yards with 77gr SMK handloads and it held sub MOA at that distance as well.

Don't believe anything you read and only half of what you see. If you need to know what a rifle will or won't do, shoot it. There is no other way.

 

[Indycar]

lilsurp comes in all different weights. The "standard" if there is one is 55 gr. They also have 62 and 68 gr so take your choice.

55 gr bullets haven't been "standard" for over 20 years. DoD went to the 62 gr in the early 80's. Complete change over (when the last NG units replaced their M16a1's with M16a2's was just after the 1st Gulf war) was in the early 90's)

Nato standard has been 62 gr since the early 80's and most of the rest of the world (excepting 3rd world countries) using 5.56 have switched also.

It continues to amaze me that most ammo manufactures push more 55 gr out than 62 gr. since the vast majority of AR's sold have a 1/9" or 1/7" twist.

Every "fast twist" AR I've ever shot (and I've shot a bunch of them), shoot 62 gr more accurately than 55gr.

 

[karl77]

My NM AR15 has a 1:8 twist, shoots 75gr BTHP moa (or less) all day. However 55gr won't group smaller than 2moa.

the advantage of the 1:7 twist is in the shorter barrel.

 

[indyjohn]

Here is an article that may help a little bit

223 Rem + 223 AI Cartridge Guide

Nice find.

 

[JTinIN]

Story goes the 1 in 7 twist was also to stabilize the M856 tracer, at distance and/or cold weather, which goes with the M885 (~ SS109) bullet with the steel penetrater. Thus the typical USGI barrel had been 1 in 7 twist for a bit.

What type application and upper are you getting (I am assuming but not sure it's an AR ;-)? For general off hand (not match) shooting probably fine with anything from 1 in 7 to 1 in 9. For just 55gr FMJ can always go with old school 1 in 12 but only if get at a good price. http://ammo.ar15.com/ammo/project/perf_whattwist.html

 

[kawtech87]

lilsurp comes in all different weights. The "standard" if there is one is 55 gr. They also have 62 and 68 gr so take your choice.

All kinds of wrong info here to be had

Well Im not one to complain about being taught the correct info. Thanks for clearing that up.

 

[jb1911]

Why do LE6920 Colts come with a 1:7 twist if it's best suited for the longest, heaviest bullet available? According to that article I mean.

 

[SSGSAD]

I own a "full size" Colt "Match" 1/7 twist, 20" bbl. and I shoot 55 gr, 62 gr, and 75 gr MATCH bulets, and do just fine... THE rifle, and the Bullets, are way more accurate than I am ...

 

[Matt52]

Lots and lots out there to read about twist rate vs bullet weight. Lots and lots of internet lore and myth. The reality is every rifle is different and the capabilities of that rifle will differ from the next one off of the line.

Here is my Remington SPS with a 1 in 9 twist barrel cut at 18".

Here is a 5 shot group of Federal Gold Medal Match 77gr SMKs at 100 yds

Here is another

Had a couple educated folks mention that it may or may not maintain bullet stabilization much past 100yds. Notice I said may or may not rather than won't. I've shot it at 820 yards with 77gr SMK handloads and it held sub MOA at that distance as well.

Don't believe anything you read and only half of what you see. If you need to know what a rifle will or won't do, shoot it. There is no other way.

for a sweet rig what chassis is that?

 

[jackadew]

I have a question about twist rates on 223 rifles. Most come with a 1in9 twist for lighter bullets but you need 1in8 or 1in7 for heavier bullets. Do the faster twist still shoot lighter bullets well and if so why dont rifles in 223 come with faster twists than 1in9?

You can not over stabilize a bullet. The problem with shooting light bullets in fast twist barrels, are light bullets are normally varmint bullets with thin jackets that can literally fly apart when they exit the barrel from over rotation. You could shoot a copper solid 35gr. bullet out of a 1/7 twist with good accuracy...because you can not over stabilize a bullet. What would happen is you would get copper fouling very quickly because the velocity of a 35gr. bullet would be very high. Bullet makers could make light bullets from an alloy hard enough that fouling would not be a problem...but then accelerated barrel wear would be the issue. It is always best to match the barrel twist with the bullet you plan on shooting and not push the bullet faster than it was made for.

 

[top hat 45]

les baer 223's are guarenteed 1/2 moa accuracy at 100 yds using a 1/9 twist with 69 gr match bullets

 

[chuddly]

55 gr bullets haven't been "standard" for over 20 years. DoD went to the 62 gr in the early 80's. Complete change over (when the last NG units replaced their M16a1's with M16a2's was just after the 1st Gulf war) was in the early 90's)

Nato standard has been 62 gr since the early 80's and most of the rest of the world (excepting 3rd world countries) using 5.56 have switched also.

It continues to amaze me that most ammo manufactures push more 55 gr out than 62 gr. since the vast majority of AR's sold have a 1/9" or 1/7" twist.

Every "fast twist" AR I've ever shot (and I've shot a bunch of them), shoot 62 gr more accurately than 55gr.

i agree the 55 gr is older...but he said milsurp...which is old stuff and if thats what he is getting then it has a possiblitly to be the 55gr.

 

[Leo]

The 55 gr and lighter bullets are not inaccurate due to weight. Most of the time when people are talking about 55 gr, they are talking about junk quality combat bullets. Try 52 grain Sierra match kings over a compressed load of Varget. That combination gets very tight 10 shot groups in a 7 twist HBAR, in a 7.7 twist Krieger barreled AR and my 8 twist 24 inch AR. The 55 grain Nosler soft points do a great job also. Likewise, a 75 grain Privi bullet shoots just ok, but a 75 gr hornady Match or a 77 grain Sierra MatchKing shoots great.

Matt52 has it right, you never know for sure until you try it out. Even then, the ballistics engineers can point you right. I built a 7mm Express rifle with a 9 twist barrel. Hornady said their 7mm AMax needed an 8 twist, they were right, the rifle would NOT stablize the heavy AMax.