Ok folks,
  What's the difference between SST and Chrome barells?  Are there other types of barells?  Thanks.

Tim

Without getting too technical

CM = Chrome Molly.  What most blued rifle barrels are made of, probably the most common.  Needs bluing, and an oil coating, or some other coating to prevent it from rusting.  Easily machined, accurate, but will wear out.

Stainless.  Similar to CM, but with nickel mixed in to the iron, giving it rust resistance, and that white steel appearance.  It wears slightly better than CM.

Chrome Lined - usually a CM barrel, with a hard chrome coating inside the chamber and barrel.  Extremely long wearing compared to CM or stainless.  invented because rifling disappears in full auto conditions in a regular CM or stainless barrel.  Some say they are not as accurate, probably because the chrome thickness can vary, engraving the bullets off center.  If you want a barrel you want to beat the snot out off, and will never wear out in semi-auto conditions, get a Chrome Lined.

Very concise, thank you.  Much appreciated.

Tim

Chrome lining fundamentally decreases the barrel's accuracy and is generally not applied to hig end tubes.  Chrome lined barrels are not as accurate.  Im not saying there are not low end stainless and high end crome lined barrels but when comparing ales to apples chrome lined is never as accurate.  Accuracy lost is probably in the .25-1 MOA range dending on whose barrel it is and how it was chromed.

Yes there are other types of barrels.  The way the rifling is cut is different.  Button rifling, cut rifling, hammer forged.  THere are other ways to line the barrel for corrosion resistance and better throat errosion prevention and thus greater life with out the accuracy loss of hard chrome.  This would be some form of nitriding.  Hopefully htat gets you off on a new line of questions to research.

Rgr that, thanks Dev!

Chrome cannot be applied perfectly evenly; thus it can never be as accurate as a match grade stainless barrel.

You CAN have a 4140 or 4150 steel barrel with match grade standards.  Stainless is easier to work, therefore it's more common to have match grade barrels in stainless.  Krieger makes fantastic barrels in 4145 steel.

MOST chromelined barrels start life as a $40 OEM rack grade steel barrel, and are not produced to match grade standards.  However, even if they were, the chrome would diminish their potential.

Interesting. So a stainless barrel wears BETTER than a CM barrel? I always heard that stainless have the shortest barrel life, but the greatest accuracy potential. I'm going to have to look into this some more.

A Wilson or Shaw barrel in stainless should ware about the same as CM while a more expensive tube will probably last longer and a no name won't last as long. It all depends on the steel and the type of rifling. As far as accuracy goes, the barrel quality prior to chrome lining is the biggest determining factor to accuracy. Chrome lining a barrel usually makes less than a half inch difference in accuracy. Some CL barrels are just as accurate as non, but that is very hit or miss. Some no name companies will make a barrel that is slightly out of spec and it may then get thrown into the bin of barrels to get lined. As you can imagine this would not help the reputation of CL barrels.

Both of mine are lined. The JT M4 puts PMC into sub 2" groups and I haven't done much other than a quick zero yet. My Model 1 tactical kit loved 50gr American Eagle and is sub-moa capable. I think the NATO chamber is the holding that back from good consistency. It seems to need more than a couple fowler shots before it settles down after a good cleaning, but chambering is another thread.

The type of rifling has no effect on barrel life.  Barrel life is controlled by throat errosion or the sand blasting of hot gas and particles wearing away the intersection of the chamber and rifling or the "throat".  As the throat errodes pressures drop, velocities drop, and accuracy will drop untill it gets so bad the bullet is having to make a huge jump across a large distance to the rifling and accuracy is complete crap.  The next step is bullets not stabilising and yawing all over the place but youd have a gun that could not outshoot an AK with Wolf long before that.

Stainless and Chromemoly simply have different wear patterns.  One gradually loses microscopic bits of steel and the other tends to lose it more in chunks.  The end result is the same... an erroded throat which leads to poor accuracy.  Chrome moly tends to withstand high temperatures better.  Stainless is easier to machine.  Stinaless is more corrosion resistant than chromemoly but hard chrome is twice as corrosion resistant as stainless. Chromemoly can be machined to a thinner proile and still stay strong and safe.  Stainless does not like arctic temperatures.  There are lots of differences.

There are also lots of different alloys of chrome moly and stainless.  Most stinaless barrels are 416R.  Most chrome moly barrels are 4140. THis thread could go on and on but I hope it just gives you more to look up because there is way too much info that could be put into one thread just about barrel steel and bore coatings.

Very intersting stuff.  I am a musician (trumpet player) and talking about this stuff is like talking about my mouthpieces... each angle of the mouthpiece accomplishes something different as does the alloy it's made of etc...  Again very interesting.

So, since there are so many takes on the subjects let me just ask:

I am a rookie when it comes to the AR-15 platform but have plenty of experience in pistols and long range targeting.  The uses I can forsee is just range time and something to "complete" the collection (short, mid, long).  

Which barrel (SST, CM, CL) would you (open to anyone) suggest to purchase?  I don't want something that's just cheap and will "suit my need".  I desire quality and something that'll last for a while.  Thanks for all the help.

Sincerely,
Tim

Some stainless barrels have a salt nitride coating making them more wear resistant compared to a CM barrel, whether chrome lined or not.

IIRC, I  believe Chromium is added to steel to make Stainless Steel and give it the  corrosion resistance  properties.  416R is used in rifle barrels and doesn't have much if any Nickel.  While 17-4PH does have 4% nickel, it's generally used in the Orthopedics industry for tools because of it's hardness.   Think a few top end barrels makers use a version of 17-4.

Get the SS if you want most for accuracy. I highly doubt you will shoot it enough to ever shoot it out. And if you do, it will costs thousands of dollars of ammo before you do it. At this point, I dont see a couple hundred hurting especially after so many years. I like CL for my SHTF and plinking guns. For range/hunting/precision/target rifles I like SS.

Thank you MDS...  btw, what does "SHFT" mean?  

Take care all, God bless.

SHIT HITS THE FAN!!!

HA...  should've thought about that one.  Thanks.

correct. this is why i wear a respirator when i weld stainless. chromium 6 can be hazardous to your health.

I always use CL bbls for my rifles.  None of them are precision shooters and neither am I.  I run 'em all with open sights or red dots and they're all basiclly SHTF rifles.

However...  My buddy really wants Rock River Arms Coyote series.  He's just getting into the AR world and is more interested in bench shooting.  I don't think the Coyote comes with chrome and he does not want stainless.

As we live in Iowa, the humidity is horrible and I he knows I have always been an advocate for chrome lining.  Is the unlined bbl still something worth while or should I try to convince him that stainless is the way for him to go?  I'm aware of the reliability issues with stainless in colder weather.

1) Who makes barrels out of 17-4? I know Noveske tried it and decided that the increased costs (about double his normal 416 barrels) wasn't worth the increased hardness...

(416 with a good hard quench goes 36-38 HRC and 17-4 will do 46-48 HRC with low-temperature aging and heat treatment)



2) Does 17-4 air harden? I was under the impression that it required a heat treat just like normal stainless.
 

what about the chrome lined barrels on colt le's?

A good Chrome Lined barrel will still outshoot most folks.  Unless you are an accomplished high power shooter, the theoretical benefits of a bare CM or SS barrel are mostly moot.

After the first time I cleaned a rifle with a chrome lined barrel I decided that other than a dedicated match upper I wanted chrome lining on everything, time spent cleaning is literally about a third the time of a regular barrel.

I'd heard something once about the cold and stainless barrels but I've never seen a actual temp figure.  At what level below zero will SS start having problems and what types of problems will they be?

Tell him to lean twards the Rock River Predator Pursuit. It is the same gun, with the exception of the barrel is a heavy national match grade stainless. THe other difference is the predator has the regular A2 stock instead of the ACE skeleton. RRA claims is shoots 3/4 MOA, but I've gotten groups at 1/2" on regular ammo on the bench.  Richt now there are several Coyote and Predator series listed on GunBroker.com for no more than list price.  Currently RRA is running months behind for ordering one.

Could not disagree more.  If you are better than a Bubba you can EASILY tell the difference in regualr CL and quality stainless barrels.  Id say the majority of people with one day of instruction in bench shooting could tell the difference from the bench.

Generic chrome lined barrels are much HARDER top clean than good stianless barrels.  They are NOT easier to clean.

If you are buying some crappy parts kit with a choice of stinless, chrome moly or chrome lined, sure the differences will be smaller.  If its a name brand stainless barrel from pretty much ANYONE it will be so far above a CL barrel its not even funny.

I dont buy and shoot stainless barrels for my AR though.  I like rapid fire, some full auto, suppressed, my rifle is used mostly off hand/on the move (where a more accurate barrel is not really a big benefit).

The barrel of any firearm is a pressure vessel with the action serving to stop up the rear end. The peak pressures involved during discharge are enormous, 50,000 pounds per square inch or more, and special steels are required to safely withstand these stresses.

Two classes of steel are currently used in rifle barrels. Most barrels for use on hunting rifles and in military firearms are made from a high alloy Chrome Molybdenum steel of the sort used in high stress components such as truck axles, connecting rods and such. In the United States these steels are designated as 4140, 4150 and 4340 types.

In target shooting stainless barrels have for the most part supplanted the use of Chrome Moly barrels. The steel is not a true, fully austenitic stainless such as is found in cutlery. The 416 type stainless steel used in barrels is one of a group of martensitic steels which can be hardened by heat treating like regular Carbon steels. 416 stainless is more accurately described as a "free machining, rust resistant" steel having a high Chrome content, around 10%, but with sulphur added to give it good machining qualities. It is widely considered that stainless barrels will have a longer life and are more accurate than Chrome Moly barrels. If stainless barrels are "shot in" using the prescribed procedure, the barrel acquires a burnishing which almost eliminates fouling, so making stainless barrels very easy to clean.

Because stainless steel is more expensive than Chrome Moly steel and it is more difficult to black due to the Chrome content, high production makers of hunting and military rifles prefer to use Chrome Moly steels. But target shooters who want the best possible accuracy from their barrels are almost without exception choosing "stainless" barrels these days.

When it comes to the question of Chrome lined or a SS barrel, re-read this man's post:

He's got the right answer. I have an AR10A4 from 1999 with a chrome-lined heavy barrel in 20" that shoots as well as the guarantee on the Armalite AR10 "T" series - that's < 1MOA at 100yds.  So those ppl that tell you that chrome lining is a absolute detriment to accuracy are guessing. Chrome lining has come a long way from your Father's day.  -  And that's not the only hardening process that's available to the shooter.

The one thing you must consider is whether you are capable of the kind of distinguished shooting that demands a SS barrel, or if you need a barrel that will outlast a CM or SS barrel with more than enough accuracy.

Bullshit.  A 1 MOA chrome lined barrel is rare.  Almost 100% of stainlessbarrels do under 1 MOA.  The best stainless barrels are more accurate than the best chrome lined barrels.  On the whole stainless barrels will be more accurate and while there is overlap, stainless is more accurate because chrome linging REDUCES accuracy.  Thats just a fact, not guessing.

You make a good general point, but I would argue even a beginning competitor benefits from the best barrel he can get.  It's often said "it shoots better than me" or "why bother getting a really accurate barrel.gun, I'm not that good myself".   That's all true if you're plinking or shooting tin cans.   However if you actually want to compete, get good, and shoot good scores in CMP, High power, Bullseye pistol, or even three gun it is important to have accurate firearms no matter what your skill level.  

The reason is simple, the accuracy of your firearm is added into your wobble area and the result is your practical accuracy.   Say your rifle can shoot into a 4" cone at 200M, and your wobble area is 6".  So in total you can shoot into a 10" cone at 200M.  Now say you have a really accurate rifle that can shoot into 1.5" at 200M. NOW you and your rifle can generally shoot into a 5.5" - 6" cone at 200M.  The result is a lot more 9's and 10's.   And let's say you make a minor change in technique.  With the accurate gun you can tell if the change makes a difference, with the innacurate gun there is inherently more randomness.   For speed shooting the result is the same.   If you're shooting at steel plates as fast as possible at 200M the more accurate rifle lets you get a away with a faster and slightly more marginal sight picture towards the edge of the plate and still get a hit.  With a rifle that shoots into a wider cone, you need an exact center hold on the plate to guarantee that your round strikes the plate.      I agree with what a prior poster said, CL for SHTF rifle, SS or CM for competition.    

It depends on what your mission is for the gun, for deer hunting here in PA where I can throw a rock and hit the damn thing, 2-3" or so at 100 is OK.  Save the money and put it into practice ammo.