Sim_Player 1,939 Posted November 9, 2015 Report Share Posted November 9, 2015 I need input. This is a 7.62 Polish Kit. Quote Link to post Share on other sites
XD45 7,124 Posted November 9, 2015 Report Share Posted November 9, 2015 The general consensus of what I've read is that nitride>chrome because reasons. Use the Google Luke. Quote Link to post Share on other sites
Sim_Player 1,939 Posted November 9, 2015 Author Report Share Posted November 9, 2015 I have already used Google to find the opinions of people that I don't know or trust. Thanks for your input, though. 1 Quote Link to post Share on other sites
Rhodes1968 1,638 Posted November 9, 2015 Report Share Posted November 9, 2015 Nitride seems superior just due to ease of construction and consistency, lot of bad chrome jobs out there. Either works if done well. 1 Quote Link to post Share on other sites
poolingmyignorance 2,191 Posted November 9, 2015 Report Share Posted November 9, 2015 Give a read and watch. It's pretty informative. https://sites.google.com/site/freeballisticcalculator/black-nitride-melonite-and-qpq Quote Link to post Share on other sites
nsnate02 32 Posted November 9, 2015 Report Share Posted November 9, 2015 Theoretically, chrome lined barrels have to be over bored to account for the chrome lining thus loosing accuracy as the chrome wears or if the lining is not perfectly even. Nitride barrels are bored to their exact tolerances and then the metal is impregnated with the nitride solution that actually penetrates the steel, so there is no "lining" At least that is what I've have been told and read in a nutshell. Quote Link to post Share on other sites
HB of CJ 1,263 Posted November 9, 2015 Report Share Posted November 9, 2015 Typical Chrome plating is only anywhere between .0005 and .001 inch thick. The parts usually are acid etched removing the PROPER amount of material before being chromed. Usually. The process is rather non forgiving. An example would be how chromed AR15 BCGs go together. Sometimes rather tight ... or loose? Yikes! Quote Link to post Share on other sites
Sim_Player 1,939 Posted November 9, 2015 Author Report Share Posted November 9, 2015 Atlantic currently has both for the exact same price. I keep waffling back and forth. Quote Link to post Share on other sites
cscharlie 107 Posted November 9, 2015 Report Share Posted November 9, 2015 It's my understanding that chrome when well done offers much higher round count while not quite conclusive to accuracy... 1 Quote Link to post Share on other sites
poolingmyignorance 2,191 Posted November 10, 2015 Report Share Posted November 10, 2015 I bought a barrel from classic and had it QPQ Nitride.. only a hundred rounds through it so far. I'll let ya'll know how it holds up. Quote Link to post Share on other sites
G O B 3,516 Posted November 10, 2015 Report Share Posted November 10, 2015 High production military reliability > accuracy you want chrome. Low production accuracy > reliability (service life) nitride. Poor chrome can peel. Good chrome not so mutch! Nitride is done by heating the part to about 600* F in a pure nitrogen atmosphere for several hours. It creates iron nitride a few molecules deep.Cannot peel. 1 Quote Link to post Share on other sites
XD45 7,124 Posted November 10, 2015 Report Share Posted November 10, 2015 One should always take internet advice with a grain of salt, but there is still valuable information if you have a good bs filter. I have read many discussions about nitriding. I was somewhat skeptical about it because it seems "too good to be true" in some ways. But after reading and watching videos I found that most of the arguments for nitriding have some scientific basis. And most of the arguments I have seen for chrome boil down to "I like chrome". I have become a big fan of nitriding. If I could get an original CHF chromed AK barrel I would grab it but for what's generally available I'd go nitrided. Quote Link to post Share on other sites
G O B 3,516 Posted November 10, 2015 Report Share Posted November 10, 2015 I have used nitrided crank shafts when rebuilding engines for decades. I had a rod bolt fail and piggy back a bearing. The bearing melted on the journal. The nitrided crank was so hard that I peeled the bearing off with a chisel - the crank journal was not hurt at all! Put a new rod and bearing in and ran it for years! 3 Quote Link to post Share on other sites
gunfun 3,931 Posted November 10, 2015 Report Share Posted November 10, 2015 Theoretically, chrome lined barrels have to be over bored to account for the chrome lining thus loosing accuracy as the chrome wears or if the lining is not perfectly even. Nitride barrels are bored to their exact tolerances and then the metal is impregnated with the nitride solution that actually penetrates the steel, so there is no "lining" At least that is what I've have been told and read in a nutshell. Not over bored. Bored to size then etched using an acid /reverse electroplate process. That leaves some irregularities. I have used nitrided crank shafts when rebuilding engines for decades. I had a rod bolt fail and piggy back a bearing. The bearing melted on the journal. The nitrided crank was so hard that I peeled the bearing off with a chisel - the crank journal was not hurt at all! Put a new rod and bearing in and ran it for years! It isn't magic, but I've never seen a blister or flake of Nitride. Can't say the same for chrome. Quote Link to post Share on other sites
mancat 2,368 Posted November 11, 2015 Report Share Posted November 11, 2015 The #1 benefit over CL is bore size consistency. I don't know that anyone has so far proven long-term barrel life vs. chrome lining. Since it is a Polish build... All of the newer Beryl 5.56/7.62x39 rifles use nitride treated barrels. As far as I know Poland is the only major 1st world military applying the process to an issued rifle. I picked a nitride barrel for the 5.56 build I've been working on with your tools. It is harder to drill until you break through the outer "shell" of the nitride treatment. I suggest going at it with carbide bits. FWIW the barrel blanks used by Arms of America and AK-Builder, I believe are all Montana Rifleman blanks, they are excellent quality. Both the bare 4140 and nitride treated barrels have shown Rockwell hardness greater than Romy CHF barrels. There is a guy on Youtube with a full machine shop that tested a batch of them. Even the non-treated ones are HARD quality steel, a huge leap from what was available on the US-made AK barrel market a few years back.. 1 Quote Link to post Share on other sites
HB of CJ 1,263 Posted November 11, 2015 Report Share Posted November 11, 2015 Crank was fine? Perfect? You was lucky and caught it very quick. Or using very good oil and soft bearings. What caused the bearing to spin? I suppose what happened to you could happen a lot but I do not think sosss. Back on topic, you pay your money and you make your choice and take your chances with rifle barrels. Generally speaking, one gets what one pays for. Just me. Respectfully. Quote Link to post Share on other sites
netpackrat 566 Posted November 12, 2015 Report Share Posted November 12, 2015 I have used nitrided crank shafts when rebuilding engines for decades. I had a rod bolt fail and piggy back a bearing. The bearing melted on the journal. The nitrided crank was so hard that I peeled the bearing off with a chisel - the crank journal was not hurt at all! Put a new rod and bearing in and ran it for years! The term "nitride" as used in the gun industry is a misnomer, and not the same as the "nitriding" that you are used to from engine parts, as they are two distinct and different processes that unfortunately share similar names. The "nitride" used for engine parts is otherwise known as "carbo-nitriding" and it is strictly a hardening process; it does nothing to prevent corrosion. Internal parts for aircraft engines such as cams and crankshafts are often nitrided, and a common problem in engines that sit unused for too long, is that the cam will develop surface rust, which compromises the nitrided surface. Then the softer steel underneath will wear quickly once it is placed back into use, leading to ruined cam lobes. What the gun industry refers to as "nitriding" is actually more properly referred to as, "nitro-carburizing" and in addition to adding hardness, it also serves to prevent corrosion. 2 Quote Link to post Share on other sites
netpackrat 566 Posted November 12, 2015 Report Share Posted November 12, 2015 I need input. This is a 7.62 Polish Kit. For two of my AK kit builds, I have used new US made barrels. One was a barrel-less AMD-65 kit which I built using a chrome lined, 4140 barrel from ak-builder.com. The other was another AMD-65 that I originally built as a pistol using a matching kit, later turned into a rifle using a blind pinned extended muzzle brake to get the barrel out past 16". This year I registered that rifle as an SBR using a form 1, and because the threads were a little boogered from my earlier work, and because I wanted concentric threads for my suppressor, I decided to rebarrel it using a 4150 "nitride" barrel, also from Curtis at ak-builder.com. I used a standard length AK barrel, and had a gunsmith shorten it back to AMD length, and thread it 1/2-28. By far, the 4140 chrome lined barrel was easier to build with. I had a little trouble drilling it for the barrel pin and had to go with a bigger oversized barrel pin than I wanted, but that was entirely my fault for getting too aggressive with the drill press (since it was going so well). Otherwise, all the 3mm holes for the gas block and FSB were easy to drill, as was the 4mm hole for the RSB. It turned out really well. The 4150 "nitride" barrel, on the other hand, was a royal bitch and a half to install. Fortunately I didn't have much trouble with the barrel pin since I was very careful to go slow, but I broke a bunch of 3mm and 4mm drills before I finally got the other parts installed, despite using cutting fluid, and being sure to run the bits at an appropriate speed. The higher carbon steel itself along with the surface treatment, simply makes life tough on the smaller drill bits needed for those tasks. That said, I am glad that I went to the trouble with the SBR of using the 4150 barrel, which wasn't available when I built the other AK using the chromed barrel. I still have one more chromed barrel and AMD parts kit, and I kind of wish I had waited to buy the barrel for it. I built the first one with the chromed US barrel for my son, and now that I have a daughter the next rifle will be for her. So at least they will be more or less the same and one less thing to argue about as they get older. Quote Link to post Share on other sites
gunfun 3,931 Posted November 12, 2015 Report Share Posted November 12, 2015 Just because the steel was tougher or harder surface or some other problems? Quote Link to post Share on other sites
mancat 2,368 Posted November 12, 2015 Report Share Posted November 12, 2015 (edited) yes, the surface is harder than that of a cold hammer forged barrel, and will eat HSS bits alive. this is another positive of nitride.. as I understand it the effect of the treatment goes deeper into the surface of the metal than the typical overall thickness of a chrome lining. even as the barrel wears it will maintain this hardness well until it's wildly out of spec, and so in theory it should take a REALLY long time to get there. Edited November 12, 2015 by mancat Quote Link to post Share on other sites
poolingmyignorance 2,191 Posted November 13, 2015 Report Share Posted November 13, 2015 Its so hard trying to strike an arc on nitride is almost like trying to weld tungsten... it's some seriously hard shit. Quote Link to post Share on other sites
netpackrat 566 Posted November 13, 2015 Report Share Posted November 13, 2015 Just because the steel was tougher or harder surface or some other problems? Combination of hard steel, and getting through the surface treatment. Could be worse. At least since I sprung for Curtis' press kit, I haven't had to drill out another barrel pin. If I ever do another of the 4150 nitrocarburized barrels, I will go to the trouble of obtaining carbide bits in 3mm and 4mm ahead of time. Quote Link to post Share on other sites
Sim_Player 1,939 Posted November 13, 2015 Author Report Share Posted November 13, 2015 Leave it to American ingenuity to improve on an almost indestructle AK design. Quote Link to post Share on other sites
6500rpm 670 Posted November 14, 2015 Report Share Posted November 14, 2015 I never thought about this until now, but if I ever plan to nitride, it sounds like it might not be a bad idea to populate the barrel and headspace before sending in to have it treated. Or populate, tear down, and reassemble after the process is completed. Good stuff in this thread. 1 Quote Link to post Share on other sites
mancat 2,368 Posted November 14, 2015 Report Share Posted November 14, 2015 (edited) ^^^ that exact procedure has been recommended by some builders - populate, drill, depopulate and send off for treatment. also here is the guy who was doing the hardness testing of some US nitride barrels vs. Euro CHF Edited November 14, 2015 by mancat 3 Quote Link to post Share on other sites
netpackrat 566 Posted November 14, 2015 Report Share Posted November 14, 2015 Thanks for posting that video, that was pretty interesting. I have a set of hardness files, but those barrels all tested below the range they will measure. 1 Quote Link to post Share on other sites
cscharlie 107 Posted November 14, 2015 Report Share Posted November 14, 2015 It was Jacob Herman, previously worked for Red Jacket Firearms, that did video of a all USA made AK with nitride barrel. James Yeager was asking him some questions about it . Jacob said that the accuracy would drop off after about 12,000 rounds due to wear on the coating... then again it was built by Century... Quote Link to post Share on other sites
mancat 2,368 Posted November 15, 2015 Report Share Posted November 15, 2015 10K rounds is about the point at which US .mil armorers will do a thorough inspection of a rifle including headspace check and bore inspection for possible replacement of barrel Arsenal Bulgaria lists expected round count of most of their firearms in the 15k range I think both of these estimates are extremely conservative, and accuracy "drop off" of 12K rounds from a nitride treated US-made AK barrel seems within the range of what is expected out of a military grade chrome-lined barrel. Quote Link to post Share on other sites
Sim_Player 1,939 Posted November 15, 2015 Author Report Share Posted November 15, 2015 I doubt my AKs will every see anything close to 10,000 rnds, under current conditions. That's the nice thing about having more than one. Quote Link to post Share on other sites
Rhodes1968 1,638 Posted November 15, 2015 Report Share Posted November 15, 2015 The only advantage I can see is concerning corrosive ammo, mostly primers at this point on milsurp. How much of an advantage that is will vary by the individual but it aint much. BTW Century does not make barrels, the supplier is in NH IIRC and they make a good barrel. Wear specs are about the same for both methods. Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.