Barrels: Chrome v. Chome-moly v. Nitride
Please educate me on barrels.
I wanted chrome lined, but locally all I can find is chrome-moly.
Also, I'm hearing rumors that nitride is better than either.
Inquiring minds want to know.
Gunco Addicted for life
the advantage of chrome lined barrels is that they drop the pressure which the ar-15 is very sensitive to. they also help with extraction of spent cases. the hard chrome lining helps barrels last longer. this is really helpful with some of the somewhat wear prone one in seven inch twist barrels.
lastly they clean up easy.
the disadvantage is they cost a bit more to make.
regular 4140 moly is just a regular barrel steel it will last a long long time with the most often used twist rate on one turn in 9 inches. it has an advantage is it is less difficult to cut the rifling in the 4140 than harder 4150 which makes for slightly better accuracy in theory. without the chrome they are finished a little more rough in the chamber. i have about as many ar-15 types with the 4140 without the chrome and they all function fine.
so the chrome is not a have to thing but it is nice to have IMHO.
stainless steel is also used for barrels. it is usually the most accurate though being a bit softer it wears a bit quicker. it should last plenty long on a sporting rifle.
the nitride is a type of finish --i figure the exterior finish is better--now about the bore i can't say as i haven't owned any nitride barrels. i would not rule it out as being a very good barrel though.
any of these should give years of accurate shots. the one that is best depends on what your use of the firearm is. tack-driver target shooting go with the stainless. survival-military get the chrome lined. all around use the moly or nitrite should do the job well.
Chrome barrels are smoother inside, so they clean easier, and cases extract easier. Fouling doesn't stick as easily too. I haven't heard of nitrided barrels, just TiN coating on tools, and that does nothing that I can tell...
Thanks guys, the nitride barrels are what DSA is now using on thier firearms.
I'm starting to lean towards an Armalite upper.
Citizen, Patriot, Ranger
Everything previously stated is correct. I will add the following:
Chrome-lined barrels are slightly less accurate due to the increased bore size that is required prior to the chrome-lining process. This also helps with the barrel's longevity. What the real difference is? No clue. Yes it makes a difference in accuracy beyond 200 meters. But not by much. Maybe an MOA. Maybe less. Chrome is more slick than steel, and copper, salts, and other fouling does not stick to it. Again, previous statements are all correct. This is one reason why the AK and SKS are both so reliable and idiot friendly.
Chrome-Moly is a reference to the alloy of the steel, again as previously stated. It's only real vulnerability is fouling. And some fouling is more corrosive than other fouling. Refer to barrel condition descriptions of "bright and shiney", "frosty", or "dark". These indicate various levels of corrosion damage. This type of barrel is usually the most accurate, all other factors remaining equal.
"Nitride" barrels are essentially the same as Chrome-Moly, but have undergone a plating process that creates a very tough surface strength. The obvious result is that is wears very well, and is purported to be very durable. The claim most often used is increased accuracy over a longer period of time. I tend to agree with this assessment since the "Nitride" process of surface hardening has been used in the performance automotive industry for better than 30 years for things like bearing surfaces, gears, and the like.
This is my opinion:
Chrome-Moly is the best all-around for sporting and general use. Think M-1 Garand or M-14, Mauser or Springfield 1903, SMLE or Mosin-Nagant. With "modern" non-corrosive primers, these barrels will last between 20,000 to 50,000 rounds with moderate loss of accuracy. The part of the barrel that wears out the fastest is at the throat, just beyond the chamber. With these "older" rifle designs, the barrel could be removed, and set-back a few thousands of an inch, and re-chambered during an arsenal re-build to restore accuracy. After WWII, this practice was essentially abandoned due to cost. A lot of the "Captured" Mausers from from the former Soviet Union were re-arsenaled in just this fashion, along with having markings obliterated, and being re-blued. The concept of counter-boring the muzzle has been well discussed on this forum, and will eliminate accuracy issues due to muzzle erosion or misuse of a cleaning rod. I have resuscitated a number of old Mosins, Enfields, and Mausers in this fashion, using a combination of these methods, returning factory or even better than factory accuracy to a 50+ year old dinosaur.
Chrome is Chrome. It is cool. It is tough. It is slick. It is somewhat more loose in terms of internal dimensions because it has to be bored and rifled a few thousandths larger than a standard barrel to compensate for the thickness of the chrome-plate. These barrels will take upwards of 40,000 rounds before losing significant accuracy. I have accurized many SKS rifles by simply setting the barrel back a few thousandths of an inch, and squaring the barrel shoulder and the receiver shoulder. In most cases, I do not have to adjust the chamber depth, in some cases, I have had to machine a new locking shoulder to adjust the head-space. I am sure that some of the "old-dogs" are spinning their heads around in a circle. Try it. I have yet to blow a case.
I have yet to actually shoot a known Nitride treated barrel. The possible exception would be late-model M-14 rifles that were selected for Counter Sniper rifles in the late 1970's and early 1980's, or purpose built early M-21 rifles. I have no certain knowledge of either from a design or armorers standpoint. Only as an end-user. If anyone knows for sure, I would like to know what you know. I could find no evidence of chrome-lining in these barrels.
That is my $ 0.02 with inflation.
Comments very welcome!!!
Imagine whirled peas
Peace, Love, And Superior Firepower
Thanks for replying.
From what I understand nitride treatment basically results in a surface hardening of ~ 60 Rockwell. A file will have a very difficult time harming this treatment as the hardness of the barrel will be very close to a diamond on the C scale. Essentially this makes the surface (bore, port, chamber, outside...) almost impervious to corrosion and exceedingly wear resistant. It is also very lubricious. Since it is not a plating like chrome, it will not adversely affect accuracy. Glock, Sig, and others have been using this process for sometime. In theory one can take a 4140 steel barrel and nitride it and it should perform the same as a nitride treated 4150 steel barrel as both hardness level will be the same. The only negative thing I have found with this process on AR barrels is that if one is assembled into the barrel extension incorrectly, the barrel may actually unscrew from the extension. The lubricity and hardness make the indexing pin installation critical.
Gunco Addicted for life
Mortismaker, That is interesting thanks for the info. I wonder if the "Max hard" (or whatever they called them) barrels that Olympic arms were selling about 10-15 years ago were nitride treated. They were supposed to be very hard and have a longer barrel life.