I searched around the forum and didn't see anyone talking about this. If I missed it I apologize please post a link to the thread. Anyway I have a savage barrel that's starting to go and I decided to look for a replacement upper. Here's a summary of my research involving how barrels are made and the differences between them that I've compiled so far. Please add your own knowledge below! Help explain the variations of barrel options and educate those who might be looking for these answers / explanations so they know what they're buying and get what they want
Rifling
Hammer Forged
Seems to be the most common. Cheap fast to produce, but any stress in the barrel blank will definitely cause increased dispersion in the shot down range. This type of rifling seems to have the highest percentage of causing a problem with accuracy, but due to low cost it's very common and often will produce a barrel that's 'good enough'
Button Pulled
Slower process than hammer forged and often paired with QPQ (quench polish quench) and perhaps some hand lapping to smooth out any burs caused by the rifling process. This is the process used by Criterion barrels and it's more expensive than hammer forged but not as time consuming or expensive as machine cut. Seems to produce very good results but due to the process of a barrel acting like a snake swallowing a mouse during the process rifling must be performed on the blank first then contoured after. This induces head to the barrel after rifling that may affect inner diameter consistency. From a risk perspective of getting a shooter versus not I would rate this in the middle category from what I know at this point
Machine Cut
The longest process requiring more man hours than the previous two. It's a cold process so can be performed after the barrel is contoured. This will avoid any of the potential problems of exacerbating any stress in the blanks and create a very consistent internal diameter through out the entire bore. This style of rifling is popular among most 1000 yard shooters and are very successful in those kinds of competitions. Due to least head and finishing the internal diameter of the barrel towards the end of the process I rate this as the lowest risk of purchasing a dud barrel that won't shoot. Also if you do get a dud these barrels cost quite a bit so you're most likely to get better customer service and perhaps a full replacement if there's issues
Contour
Varmint / Target
Heaviest barrels, will gather heat at the slowest rate but also dissipate at the slowest rate once it's hot. One thing I found is that if the barrel is not fluted the heat often doesn't affect accuracy much from what I've witnessed out to 400 yards. The biggest down side to the heat is creating an awful mirage in the scope so the target appears to be where it isn't. A heat shield can deflect the mirage and improve your site picture
Sporter
I think most AR barrels fit this category. Kind of a middle ground between a heavy but not a pencil barrel. They will do well overall but may not see the insane accuracy of a 6mm Varmint barrel throwing shot on top of shot at 400 yards
Feather / Pencil
This is the thinnest barrel often used for hunting applications. It'll be accurate for the first 3 to 6 rounds then start to string out after without cool down. They get hot real fast! Great in hunting applications, not so good for competitions or just fun plinking IMO
Fluting
Debate Flute or not?
Fluting is applying cuts into the barrel to increase surface area with the idea of both cooling faster and reducing weight. Studies on affects to accuracy have shown that the barrels may string shots after it heats up in some cases where the fluting was too deep, occurs sometimes with SDM fluting that's improperly performed. This is due to the fluting actually causing different sections of the barrel to heat up inconsistently and it'll create a bend in the barrel. So your shots start to 'walk'. I haven't witnessed this myself, but my understanding is a reputable shop now knows how far they can cut fluting and this isn't as much of a problem in 2022 as it was in say 2012.
SDM / Narrow
These are slightly deeper cuts and more narrow. Shaves off the most weight and adds the creates the most surface area for cooling
Standard / Wide
Wider cuts and fewer around the outside diameter of the barrel. Less weight reduction, but still adds some surface area for cooling
Twist Rates (specifically in 223/556)
Overview
Twist is measure in how many inches a bullet must travel to rotate 360 degrees. For example 1:7 means every 7 inches the bullet will finish 1 rotation. Twist rate is used to stabilize a bullet so it travels straight. If a bullet is not stable it will tumble and you will see 'key hole' marks on paper where bullets have passed through sideways. A faster twist will create more friction on a bullet so a 16inch barrel that's 1:7 will fire rounds at a slightly slower velocity than one that's 1:12 as the round isn't going to have the same pressure applied to it as it's spun up to a higher rate. The advantage of a 1:7 over 1:12 is that you can stabilize heavier / longer bullets that won't be as affected by wind conditions and hit harder having a higher ballistic co-efficient rating. If you don't plan on using 75gr 223 rounds you don't need a 1:7 twist. Faster twist rate does not mean better accuracy in my experience
Faster Twist 1:7
These will stabilize heavy rounds enabling you to use 77gr rounds through the rifle and still have good results on paper at long range. If you plan to mostly use 55gr rounds this will still work fine but not necessary
Slower Twist 1:12 or 1:9
Heavy rounds will still fire safely through these barrels but you may not be happy with the results on paper! If you're only using standard 55gr weights this will work
Chamber Cuts (223/556)
NATO 5.56
Wide
Longer free bore, less aggressive engagement into the rifling
Wylde
Medium
Same long free bore as NATO 5.56 but more aggressive lead into the rifling
223
Tight
Shorter free bore and aggressive lead into the rifling. Due to combination of shorter free bore and aggressive lead into rifling it increases the pressure and can cause a safety issue with 5.56. Do not run 5.56 in a barrel stamped 223!
Hi CountZero,
You have put a lot out there for commentary. I probably won't get to all of it!
First, there are pros and cons to all the methods of rifling. All work well enough for the shooting we do at an Appleseed clinic.
I have many rifles and single shot pistol barrels that are both hammer forged or button rifled. Pretty sure I don't have any with cut rifling. All shoot well.
Second, Hammer forged barrels have a reputation for being more resistant to wear than button rifled barrels. Button rifled barrels have a reputation for being more accurate than hammer forged. To both of those points I say: Yes-No-Maybe? My rifles and single shot pistols all shoot near MOA with their favorite loads-whether rimfire or centerfire-whether they're factory barrels or ‘match' grade. To this end I like the great gun writer Warren Page's take: "Only accurate rifles are interesting". Unless you're a benchrest shooter, I would not get too caught up in how your barrels are rifled.
Barrel contour is another matter.
Fat barrels are stiffer than the slender pencil thin barrel. This means a fat barrel will vibrate less and is usually more accurate during sustained fire: like that at an Appleseed clinic. Slender barrels certainly have their place, especially where hunting is concerned.
Fluting a barrel has the benefit of making a barrel lighter while retaining most of the benefits of the fat barrel. But I also think fluting is a bit overrated.
Bull barrels. A bull barrel is simply a barrel with no taper-diameter isn't really part of its definition. But, most people think of a ‘bull' barrel as a fat barrel with a diameter in the neighborhood of one inch.
Twist
Twist is huge. Gotta match the twist rate for the bullets you plan to throw at the expected velocity for the caliber. If your bullets aren't stable nothing else matters. Not going to delve into twist rates for every caliber-too time consuming. Do a google search on that.
That's about it for now. Good topic. Fun conversation!
In Liberty,
Gus
Thanks Gus for your thoughts! First disclaimer, I am not throwing crap at one process or type of thing over the other. I'm just gathering information trying to understand the pros and cons of the things that go into a barrel, the choices that are available and why you may select one over the other.
To expand a little on the rifling methods: machine cut, button pulled, cold hammer forged. I think it's a matter of playing the odds. From a discussion with the old man at Krieger I'll try to summarize what I learned about this and why it makes a difference.
Finish the inner diameter first or last?
Krieger was of the mindset you probably want to finish the inner diameter work of a barrel as late as possible in the process to get it as consistent as possible down the entire length of the barrel. Also you want as little heat applied to the barrel as possible after the inner diameter is finished to maintain consistency.
Pre contouring
Cold hammer forged rifling and button pulled must be completed before the contour of the barrel is finished. This means a lot of heat will be applied after the rifling is finished. Also while the rifling is being formed any stress fractures in the blank will be worsen due to the rifling process itself and then adding heat to it certainly doesn't make it any better.
Stress fractures, what can they do to a barrel?
They could create parts of the barrel that open up slightly or tighten up a little bit on a given land. This might imply an inconsistent spin on a bullet or create a wobble that wouldn't be there otherwise causing groups on paper to open up. This is where you're playing the odds. If the blank is good and no fractures it's not a problem, if it does then it could be minor could be severe
Bottom line?
Even a machine cut barrel may have stress fractures, but since the contour is cut first and rifling after there's less chance of the heating up of the barrel via the machining process to affect the inner diameter consistency of a machine cut barrel over button pulled or cold hammer forged. That said I believe you could as I have had barrels that are CHF perform at moa, but your just rolling the dice. A company like POF and Daniel Defense will be more likely to stand behind their product and replace or fix it if it's not performing to your standards, and their quality controls could prevent bad barrels from getting out into the public, but it's an interesting dynamic to consider.
Here's an article to consider reading. I believe the top 4 or 5 are using the machine cut process in their manufacturing:
https://precisionrifleblog.com/2019/01/05/best-rifle-barrel-2/ (https://precisionrifleblog.com/2019/01/05/best-rifle-barrel-2/)
Twist
Twists are subject to your caliber of choice and bullet weights. So there's a bit more personalization going on here. I am not a hand loader so I don't get into the gritty details here. I just know once a bullet is stable it's stable. Gunblue490 on youtube talked about this a bit said you can't over stablize a round but you can tear it's jacket off if the bullet is too hot with a fast twist. It's only an issue for hand loaders so if you're using factory ammo just match up your twist with what weight/bullet length you tend to shoot and you should be fine. From what I've experienced this seems to hold true but I'm open to other thoughts and willing to learn!
Good stuff! Take care
Recrowning
Was discussing some things again last week or so and had this come up as an option. If you have a barrel that's just not producing good groups or used too but no longer is you can have a smith cut a new crown on the barrel. Cut it back a few thousands and make a new finish. The idea is if your crown is damaged your groups will suffer. Also it maybe the barrel harmonics are off and cutting the barrel back a tad might be worth a try.
This is something Krieger and Bartlein have mentioned in videos and I've asked around locally, I guess it's a thing. I had no idea but I guess it is worth a shot if you got a wall hanger and have the funds to try to restore it
Most folks can't shoot to 4 MOA to begin with, so it's not especially relevant to what we do at an Appleseed. However, if you're interested in the nuances of barrel manufacturing, Ian and Karl at InRange did a series of interviews with Faxon about the topic. I think you'll enjoy them.
Part 1: https://www.youtube.com/watch?v=e2X1iaQbjg8
Part 2: https://www.youtube.com/watch?v=yF4g2CWtjOo
Part 3: https://www.youtube.com/watch?v=R3FDLiWMUTc
Part 4: https://www.youtube.com/watch?v=ZDvLrvEAhkM
Very nice! Thank you! If I learn something new to expand on the stuff I summarized above I'll be sure to include it. I understand most attendees of AS are not 1000 yard precision contenders (myself included) but I think this info is relevant to the Rifle Knowledge Bank.
I at least find it interesting to understand, though if the mods want to delete the thread that's totally fine, won't be the first time haha
Actually very glad you said something Nashville! I've copied the info a document just in case this thread does get removed.
I've made it through 2 of the 4 videos, 1.5x speed is a wonderful thing! Very cool. I like how they brought up the history of the process. I didn't know cold hammer forged was invented by the Germans in ww2 to speed up the manufacturing process and the original M16 was button pulled rifle! Very cool. Plus makes sense the older ww1 barrels were cut rifled due to the stresses involved in button pull and later hammer forging. The metals of the day probably wouldn't like it very much!
Thank you for sharing the links, I look forward to the next 2 segments.