Confused about twist rate

[Shadowfax]

I am confused about what twist rate would be best to buy for my first AR-15 in .223. I have read, from people who sound like they know what they are talking about, that a twist rate of 1:9 would be optimum for bullets in the 52 to 69 grain range. That sounds perfect and would allow me to start with some commercial grade 55 grain off-the-shelf loads with the possibility of moving to some slightly heavier hand-loads in the future. The problem is that many of the popular uppers that I see, for example at Bravo Company, etc, have twist rates of 1:7, yet most of the reviewers that I have read are impressed with how accurate their guns are. Is this a case of comparing apples and oranges? Are all 3-gunners hand loading and using heavier bullets with the slower twist rate to hit targets at 300-400 yards, where the average shooter is happy to hit a target with commercial ammo at 100 yards? As I said, this is my first AR-15 -- actually my first rifle of any kind larger than a .22. I have been shooting pistol for about a year and go to local USPSA style matches 3-4 time a month. There are a few local (Southern California) 3-gun matches that look like fun. I would like to get a gun good enough that I would be able to compete given enough practice, however I am not expecting to win the Nationals or anything like that any time soon. If it matters, I was planning on getting a 16" mid-length, or an 18" or 20" rifle-length gas system.

[Jesse Tischauser]

1:8 is the compromise that works well for just about everything. The 20" Firebird I used to own, the 18" JP I currently own, and the 18" LOKI I will soon own all have 1:8.

[aessu]

Get a rifle length. 1:7 twist (wich is faster than 1:9, not the other way around as you say) will shoot those 52gr bullets just fine.

[kurtm]

The answer to this isn't nearly as simple as "get the 1X7 twist and all will be good. EVERY barrel you buy will be different than EVERY OTHER barrel. We can talk in general terms, but each barrel performs differently than any other. Exaples of this are, J.P. 1X9 twist that shoots 77gr bullets (which should be too heavy for this twist) into 1/2 M.O.A. at 300 yards. A nice Saber barrel in 1X8 twist that hates anything over 55 grains.

IN GENERAL a quality barrel that has a twist in the 1X7-1X9 will be just fine, for most weights we shoot, I see no need for the 1X7 personally and don't care for Chrome lining, I have found 1X8 to be about the best twist rate for anything you want to shoot, and I own several 1X9s that work great...BUT they are all good barrels. DPMS, J.P. Wilson, Satern, Compass Lakes.

[bigbrowndog]

I would agree with Kurt on this,............WAY TOO MUCH Attention or Concern is given to an AR's twist, I have everything from 1-12 to 1-7 and everything in between, they all shoot everything from 40grs to 69grs well, Since I do not shoot much anything heavier than 60-65gr bullets for the most part they (AR's) all shoot great for competition, occasionally I shoot 75-77gr bullets and my rifles that are spun 1-9 to 1-7 shoot them just fine. The ONLY way to tell if your rifle will do well is to go and shoot it, as Kurt said, you just never know how each individual rifle will perform until then.

Start with a good barrel and you should not be disappointed, remember to try different styles of bullets of the same weight as well, because its not just the weight of the bullet but also other factors that determine how well or poorly a particular bullet will fly.

trapr

[Graham Smith]

The smaller the number, the faster the spin. In general, heavier bullets need to be spun faster or they will destabilize. Lighter bullets will go faster than heavier bullets, but heavier bullets are less subject to wind deflection at distance.

Generally speaking, a 1:9 barrel is OK for 55gr, a 1:8 barrel will work on anything up to the 69gr Sierra Match Kings that are so popular. A 1:7 will work with the 75gr or greater bullets.

An 18" 1:8 barrel has sort of become the defacto barrel but any 1:7 to 1:9 will probably work equally well for standard 55gr loads.

[2011BLDR]

1 in 7” is a Milspec requirement to stabilize tracer rounds. 1 in 8” is all that is needed for everything up to 77gr. A 1 in 9” may or may not stabilize 75 or 77gr bullets. Every barrel will be slightly different and have better or worse performance with different ammo.

Out.

2011BLDR

[Shadowfax]

Thanks for all the information -- it is hard to determine which are the important details and which are superfluous. I am now thinking of getting a barrel from Black Hole Weaponry <http://www.blackholeweaponry.com> -- 18", Stainless steel, standard profile, 3 groove rifling with 1:8 twist and rifle length gas port -- there is a group buy going on one of the other forums for $165. I was planning on trying to get a complete upper, but this way I can order exactly what I want -- and if I get stuck, I'm sure I can find some excellent advice on this forum.

[gerritm]

Not to hijack this thread but I have a 16" Daniel Defense barrel with a 1/7 twist. It seems to shoot 55 and 75gr well at long distances from 200 to 300 yards. I guess my question is does the 1/7 twist have a negative effect on the lighter grain bullets? Will it not stabilize them as well or does it just shoot the 75gr better than a 1/9.

[jwfuhrman]

My Barrels on all 4 of my AR's are 1/7 BravoCompany(BCM) barrels. I have a 11.5in SBR, 14.5in Mid length General Purpose Carbine, 16in SS410 on my 3gun and a 18in MK12 Mod 1 SPR.

I shoot 68gr bullets in the 11.5in and 14.5in and 75gr in the 16in and 18in.

Ive found BCM barrels to suit MY NEEDS the best. Only other barrels I look at are Noveske and Daniel Defense. But thats just me and my preferences, as the only rifle that isnt built around a "real world" purpose is my 3gun rifle. Otherwise the rest of my builds have been built from recommendations(that turned out to be what works for me) from guys over on m4carbine.net (which, I have found to be 100% more knowledgeable and intelligent and helpful than anyone on AR15.com)

[jwfuhrman]

Not to hijack this thread but I have a 16" Daniel Defense barrel with a 1/7 twist. It seems to shoot 55 and 75gr well at long distances from 200 to 300 yards. I guess my question is does the 1/7 twist have a negative effect on the lighter grain bullets? Will it not stabilize them as well or does it just shoot the 75gr better than a 1/9.

To answer your question, the 1/7 can acutally put TO MUCH spin on a sub-52gr bullet causing it to literally spin itself apart mid flight. 55gr-77gr bullets are G2G with 1/7 twist. My training ammo is all 55gr XM193 or American Eagle 55gr, no problems thru any of my guns, other than the 55gr XM193 isnt the most accurate "distance" bullet. Over at m4carbine.net we refer to using M193 ammo the accuaracy is MOM(Minute of Man) instead of MOA(Minute of Angle). Your gonna hit a man sized target at 300+ yards, but your not gonna set any records for accuracy.

[kurtm]

Counter-point!

I have a 1X7 16" Colt barrel that won't shoot any bullet very well EXCEPT a 50gr V-Max as fast as I can push it which is right around 3200 from that short of a barrel and I have never had a bullet "spin apart" even with these light jacketed varmint bullets. This barrle HATES 75/77 grain bullets with a passion to the tune of 4-6 M.O.A at 200 yards....so as you can see it depends on the barrel it's self more than anything else!

[sniperfrog]

I keep seeing people refering to the weight of the bullet as what determines twist. This is not true. It's the length of the bullet that determines what twist you need. To make a bullet heavier you typically have to make it longer so usually it's the heavier bullets that are also the longest. However, if your bullets are constructed of a different material than a lead core, it could be really long yet have a relatively low weight, or vice versa.

Example:

At work we use some reduced richochet limited penetration frangible ammo. The bullets are 62 grains but they are slightly longer than a 77 grain Sierra. The're made out of some tin/copper alloy with a copper jacket and the're flat based as well. A 1-9 twist will not stabalize these at all. We had to switch all of our M4s to 1-7 twist barrels to use this stuff. The Barnes solid copper bullets are really long for there listed weights as well.

I also did some testing of the old Powell River Labs powdered tungsten cored bullets. These weighed 87 grains but were about the same length as a 69 grain Sierra. They would shoot through a 1-9 twist just fine.

A 62 grain M855 "green tip" bullet is longer than a 69 grain Sierra match king.

Some barrels will surprise you on what they shoot well and don't shoot well. I like to err on the side of caution and go a little faster than I need. This means a 1-8 or a 1-7twist.

Edited September 2, 2010 by sniperfrog

[jwfuhrman]

Your counter point is probably true. Ive not been impressed with Colt AR stuff, just not my thing. BCM, DD, and Noveske stuff seems to work better from what Ive seen, at least on m4carbine.net

But thats just me.

[kurtm]

"Your counter point is probably true" (Jon Fuhrman)

Is that your fancy way of saying I "might" not be lying?

[bigbrowndog]

my question?????? Has ANYONE actually seen FIRSTHAND, a bullet come apart in flight, I know I've heard a whole bunch of urban legends about it, but have NEVER seen it myself firsthand. Plenty of folks SAY!!! they've seen it but then people say that "nothing in the woods can throw rocks"

and "they saw the bodies being pulled out of the Archuleta" or "they've seen the photographs of the underground alien/human compound" and of course our local favorite, "there is nothing worse than an angry giant short faced bear"

So go get a barrel 1-7 to 1-9 twist, and go shoot it.

trapr

[gerritm]

I don't know about one breaking apart, but the DD 1/7 barrel does seem to shoot well. I have never checked the MOA vs MOM @ 200 yds. but we were shooting & hitting the small round flashers at 300 yards and hitting them with 55gr PMC and 75gr Wolf match ammo. They were fairly flat shooting with very little hold over. That is the longest I have shot. My buddy was shooting a 1/9 with the 55gr PMC's and he was also hitting them with no problem. I have shot 62gr reloads and 75gr wolf regular cheapie ammo and they are all over the place. So it does pay to try different ammo until you find what the barrel likes.

[jwfuhrman]

I had a 45gr Federal bullet fly apart on my when I first went with a 1/7 twist. Not EVERY bullet is going to blow up that is sub 52gr shot out of a 1/7 twist. The sub 52gr bullets are TO LITE when to be spinning as fast as they are when used thru 1/7. It may blow up, it may not, but that bullet is spinning way to fast for as fast as it is traveling. I dont use anything less than 55gr anyways, so 1/7 is what I prefer so I can shoot the heavier stuff I want too.

Wolf Ammo is not know to be the most accurate, no matter what the bullet weight. I run mostly Hornady(75gr) and some 68gr Dallas Reloading Service rounds that I got from AmmunitionToGo.com, with ALL of my practice/carbine training ammo being 55gr XM193 or American Eagle 55gr.

[jwfuhrman]

"Your counter point is probably true" (Jon Fuhrman)

Is that your fancy way of saying I "might" not be lying?

nope, just saying it might be true for you, but not me. I dont post here much, only when I see something worth while posting in. Im on M4C much more, and get my info from there, from people who use this their guns for more than just gaming, or range toys. Not questioning your experience, just stating the facts that I know

[kurtm]

So let me get this straight. The Colt barrel I HAVE, and HAVE shot and KNOW what it will shoot well and what it DOESN'T shoot well (which is TRUE for me), if you owned it it WOULD shoot 77 grain bullets well (Which would be TRUE for you)? That would be some kind of majic.

The data I posted isn't some kind of it might be true for you/ true for me kind of thing. It is more like empirical data, and no matter how much you would like to think that if you owned it it would be different, it wouldn't be, so you are kind of telling me that you think I am lying, so is you is, or is you ain't?. The counter point was to show that no- matter what it is barrel wise, it will be different in QUANTIFIABLE performance barrel to barrel, and there isn't much think or feel in any of it. Kurt

[bigbrowndog]

So what was your PROOF that the bullet flew apart??? because you missed the target??????????

As for using guns for purposes other than gaming and range toys, does not mean you KNOW what is happening, or that your facts are correct, if you have read it somewhere then it is still HEARSAY, and not FACT.

Your statement "but that bullet is spinning way to fast for as fast as it is traveling" seems to be one that would require some knowledge or expertise in physical dynamics, however it sounds like mall ninja speak!!!

Many people throw the phrase "its not accurate" around like a detractor, however rarely do they provide the empirical data to back up the claim, what is "not accurate" to you??? my definition changes depending on what I ask of the gun, I also do not place much faith in 100yd accuracy claims, simply because many times they do not correlate to further distance performance, I prefer 200 and beyond.

I have said previously you cannot lump all your data into one fits all category, you Must go and shoot your barrel.

trapr

[Stlhead]

I for one am thankful that Mr. Fuhrman has chosen to share with us the wisdom that he has learned from another forum where people actually use their guns for more than just gaming. As he has been more than helpful by not only stating his opinions but telling us where we can find the original opinions (from other people on the internet who use their guns for more than just gaming) that he is parroting in this thread. I did not stay in a Holiday Inn Express last night, but it would seem to me that actual personal observations would be more relevant to the discussion than the second hand accounts of what anonymous people on a different forum (where the original poster did not choose to pose the question) might think. I am not saying that all of the people on other gun forums are mall ninjas, but I do believe that B.E. has one of the lowest rates of mall ninjitsu of any gun forum I have encountered, can the other forum make this claim?

I have personally tried a number of different twist rates and have come to the conclusion that for what I do the quality of the barrel and the contour is of much more importance to me than the twist rate. I have to admit that I have only tried 1 in 7, 1 in 8, and 1 in 9, and that I have only tested bullet weights of 55 to 69 grains. My favorite 5.56 barrel right now is an 18" JP medium contour 1 in 8 and it seems to shoot everything well. Unfortunately, I only use my rifles to game, so all of this information may be suspect. Another mystery to me is that some loads seem to shoot well in any gun. Has anyone found that a barrel that did not like a 69gr SMK over 25 gr of Varget?

I have heard of this Minute Of Man, I don't shoot at men, I shoot at targets. As for the quality of the information that can be gleaned from a forum where people use there guns for more than just gaming (I can only wonder what that is), the original poster seemed to be interested in gaming, would this not be the best place to get his answer? Or would you have him ask his question the other place where they use their guns for OTHER than gaming?

If it is not clear by my repeated use of the phrase "where people use their guns for more than just gaming" it has struck me as the sort of comment a person would toss out instead of backing up a previously made statement with evidence or at least a convincing argument, and somewhat condescending too those of us that do use our guns to compete with. It would be easy to toss out a personal attack in response to this perceived jab, but instead I will ask you to help me understand. How did you know the bullet came apart, how many times did it happen? Give us some details and information to back up your claim. Also if you could tell us why the information on the other site is so much better than the info on this site that would be of great interest to me as well.

Thanks!

(sorry I type so slow)

Edited September 2, 2010 by Stlhead

[Jesse Tischauser]

Im on M4C much more, and get my info from there, from people who use this their guns for more than just gaming, or range toys.

Yeah having your gun ride around in the trunk of your squad car or sit in an armory is a much better way to see how it shoots as compared to putting 15-20k down range in training and competition.

You just lost all of your credibility on this forum my friend.

You might think about going back to that not posting much status.

[jwfuhrman]

Ha, wow, f*#king gamers. My bad for wasting your time with facts that can be backed up by Vets, Contractors and Cops. No wonder I dont post here. About as bad as AR15.com....

[bigbrowndog]

Ha now thats funny!!!! because I'd bet everyone that posted to YOUR comments are VETS, COPS, and such.

Sorry we hurt your feelings but I still do not see your FACTS listed anywhere, but then I'm just a Vet, public servant, I have contracted before but it was to a govt entity that I can't talk about

As for your f^c&ing gamer comment, that sure is pretty shirt you wear on your avatar.

trapr

Edited September 2, 2010 by bigbrowndog