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Posted: 2/20/2016 3:59:01 AM EDT
[Last Edit: 2/20/2016 3:30:00 PM EDT by Grizbacker]
So I'm thinking about doing a dedicated bump fire build. Purely a fun gun. Would chrome lined or salt bath nitride be a better option as far a barrel life for a rifle like this that will experience a lot of rapid fire and total rounds? I seem to be finding mixed opinions in my searches. Ease of cleaning is of some importance as well but first priority would be which will hold up better for a dedicated bump fire build. Thanks in advance.


Edit, Poll added. These are the two barrels I have laying around to use for this project. Not sure which to go with. I already have both barrels so cost really isn't a factor.

Daniel Defense midlength s2w profile (heavy profile) chrome moly vandium cold hammer forged salt bath nitride
Vs
Daniel Defense carbine m4 profile chrome moly vandium cold hammer forged chrome lined.
Link Posted: 2/20/2016 4:16:06 AM EDT
I have no idea which one is better but if forced to choose I would probably go chrome just because of its track record.
Link Posted: 2/20/2016 5:42:51 AM EDT
I would likely go nitride.  Cheaper and will possibly last longer.  Feedback that I've heard has been good so far.
Link Posted: 2/20/2016 7:27:55 AM EDT
[Last Edit: 2/20/2016 7:29:13 AM EDT by CavScout8]
Nitride vote. It's cheap. If you actually wanted a service gun with full auto capabilities that you could take to war, I'd suggest double chrome lined bore, fluted heavier profile, polygonal rifling if possible, and maybe CHF.

For a bump fire gun... shoot Wolf .223 and just shoot cheaper barrels bores out all day long. You go too cheap and you'll probably end up fussing with the barrel over mere quality control issues.

Pretty sure nitriding is significantly less wear resistant than chrome. Especially if you're shooting the harder, bimetal jacketed Wolf ammo. But if there's no price difference of the same grade of barrel between the two, then I vote chrome.

You might want to consider a heavier profile barrel as well, as they handle the heat better in general (from bump fires). I'd think with a thicker barrel, it'll flex less from the heat and therefore probably wear less from firing while hot and flexing.
Link Posted: 2/20/2016 7:36:42 AM EDT
Nitride provide greater Nti wear properties and will be inherently more consistent.
Link Posted: 2/20/2016 7:53:47 AM EDT
Still no real evidence one way or the other.

Henderson Defense has both running and will likely provide the answer at least to which keyholes first........

I'm a chrome lined type guy usually but for the build you describe i'd use nitride simply because of price.
Link Posted: 2/20/2016 8:06:04 AM EDT
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Originally Posted By faawrenchbndr:
Nitride provide greater Nti wear properties and will be inherently more consistent.
View Quote


Can I get your source for wear resistance between chrome plated and melonite'd steel?

Nitride will be a good cost savings probably.
Link Posted: 2/20/2016 8:12:35 AM EDT
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Originally Posted By CavScout8:


Can I get your source for wear resistance between chrome plated and melonite'd steel?

Nitride will be a good cost savings probably.
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Originally Posted By CavScout8:
Originally Posted By faawrenchbndr:
Nitride provide greater Nti wear properties and will be inherently more consistent.


Can I get your source for wear resistance between chrome plated and melonite'd steel?

Nitride will be a good cost savings probably.



Just info I have gotten from barrel manufacturers. That and experience with aircraft parts, both hard chrome and Melonite treated. Tons of information out there about the subject. So I guess for someone like you who always questions a comment and demands source documentation, it may be considered speculation. Do some research and teach yourself something.
Link Posted: 2/20/2016 9:37:26 AM EDT
[Last Edit: 2/20/2016 9:37:59 AM EDT by acman145acp]
I'm just going to leave this hear........ it's at least as relevant as speculation , aircraft parts and statements from people trying to sell barrels.


http://www.dtic.mil/ndia/2002gun/waterfield.pdf

Considering how cheap nitride barrel's are and the potential for improved accuracy.
I hope they do prove to last longer but as of now none exist that i've seen.
Link Posted: 2/20/2016 9:48:08 AM EDT
[Last Edit: 2/20/2016 9:49:13 AM EDT by StealthyBlagga]
Compared with the $$$ you will waste on aimlessly spraying spend on ammo, the price  differece on the barrel is trivial. I'd just get the cheapest barrel I could and keep shooting it until it keyholes.
Link Posted: 2/20/2016 9:55:13 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By acman145acp:
I'm just going to leave this hear........ it's at least as relevant as speculation , aircraft parts and statements from people trying to sell barrels.


http://www.dtic.mil/ndia/2002gun/waterfield.pdf

Considering how cheap nitride barrel's are and the potential for improved accuracy.
I hope they do prove to last longer but as of now none exist that i've seen.
View Quote



Some good info there.......thanks
Link Posted: 2/20/2016 9:57:27 AM EDT
[Last Edit: 2/20/2016 10:00:12 AM EDT by MS556]
The jury is still out on round count barrel life between the two.  There are a huge number of other variables that make comparisons difficult.  To my knowledge, no one makes exactly the same barrel from the same material, heat treated exactly the same way, stress relieved exactly the same way except for chrome lining one and nitriding the other.  Nor are all chrome lining processes done the same way.  And there are several different nitride methods.  Then you would have to define the end point.  Will it be when a certain degree of accuracy loss occurs, or when bullets keyhole, or some other event?  The ammo must be the same and rate of fire and cleaning intervals the same.

No one has done this.  I don't know if anyone but military ever will.  All we can say at this point is that nitride, particularly the QPQ SN  variety, is very good when done right and dramatically extends barrel life.  Whether, all other factors being equal, it matches or exceeds chrome lining remains unknown.

In the use described by OP perhaps barrel material might be the determining factor.  4150 CMV cold hammer forged might be indicated and as important for sustained bump fire as trying to make fine distinctions between nitride or chrome lining.

Where match grade accuracy is not needed, as in OP's use, barrels are cheap and replacement easy.  He will spend a lot more on ammo than on barrels.
Link Posted: 2/20/2016 10:10:28 AM EDT
Molon will be doing a side-by-side comparison later in the spring & summer...results will be interesting to see I'm sure.
Link Posted: 2/20/2016 10:29:46 AM EDT
We need to get a Nitride and CL barrel as an ARFCom community to pass around and document the wear.  Shoot 500-1k ship it to another ARFCom member, another 500-1k, and so on. Find members who can shoot that amount in a short time span so this thing doesn't last 10 years lol. We would need someone with no bias that is reputable to gage the wear. I assume most don't have the tools or knowledge to do so.

That's my plan to answer this question once and for all.

Link Posted: 2/20/2016 10:37:40 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By MS556:
The jury is still out on round count barrel life between the two.  There are a huge number of other variables that make comparisons difficult.  To my knowledge, no one makes exactly the same barrel from the same material, heat treated exactly the same way, stress relieved exactly the same way except for chrome lining one and nitriding the other.  Nor are all chrome lining processes done the same way.  And there are several different nitride methods.  Then you would have to define the end point.  Will it be when a certain degree of accuracy loss occurs, or when bullets keyhole, or some other event?  The ammo must be the same and rate of fire and cleaning intervals the same.

No one has done this.  I don't know if anyone but military ever will.  All we can say at this point is that nitride, particularly the QPQ SN  variety, is very good when done right and dramatically extends barrel life.  Whether, all other factors being equal, it matches or exceeds chrome lining remains unknown.

In the use described by OP perhaps barrel material might be the determining factor.  4150 CMV cold hammer forged might be indicated and as important for sustained bump fire as trying to make fine distinctions between nitride or chrome lining.

Where match grade accuracy is not needed, as in OP's use, barrels are cheap and replacement easy.  He will spend a lot more on ammo than on barrels.
View Quote



I agree.
You throw into the mix that Henderson Defense had 30-50k rnds down the pipe last i saw of both fn chf and psa nitride 10.5" (about as cheap as you can get if you wait on the sales) with neither keyholing yet it makes the cost of barrels pretty insignificant in the big picture.

The OP would probably be better served picking a barrel that had the contour etc that suited his needs.
Link Posted: 2/20/2016 11:02:28 AM EDT
Most foreign made issue assault rifles - full auto - are cold hammer forged nitrided, since the 1970s. HK for one. Therefore the track record IS out there on nitride if some research is done. Otherwise all you will read about is how great the chrome lining in the M16 works, because that is all the American shooter knows about.

Colt kept that spec going because it was cheaper for them and it worked. Given that CHF and nitriding is the continuing trend and the M4 is about the last weapon to use it bears on the discussion.

Look to full auto MG's for barrel treatments across the globe and you get the better answer. Some claim the PSA - FN M249 barrels in a different alloy work best when available for the AR15.

The real point is that it will take shooting over 200,000 rounds a year to find out, with a hundred different barrels, to see a realistic trend. Since it's going to get burned up anyway, I wouldn't bother spending any extra on it for a "potential" increase in barrel life. It will spray and pray up to 8MOA and get the results, same as issue. Another $100 won't be a guaranteed better barrel unless they show you their test of 100 barrels which all shot 200,000 rounds.

Very few makers do that, it's expensive. Very few demand that level of proof. Most makers just gild the lily in advertising because we will never shoot it  enough to know. One thing is sure, tho, regardless of what barrel you get, running a lot of ammo thru it hot will erode the throat eventually and there goes the accuracy, no matter what.
Link Posted: 2/20/2016 11:05:55 AM EDT
[Last Edit: 2/20/2016 11:10:40 AM EDT by jasonm4]
Nitride/melonite is superior to chrome lining and has been around a lot longer than most folks think. I believe it was first used in the automotive industry a few decades ago. It beats chrome line properties in all categories. Not just a longer life, but far better wear properties, corrosion protection, and easier to clean. But as mentioned, there hasn't been tons of experiments to back that up on a firearm, even though it has been around like on the WASP or SCAR. The main factor is that the base metal is of good quality and is cut perfect since the nitriding process adds no material. On my last build I bought an unlined 4150 barrel and shot it around 500 rounds. Then I had it cleaned out and melonited. It's one of my most accurate rifles. It won't pit or flake like chrome and I wouldn't be surprised to see the military adopt this over chrome lined in the future, but they are slow to make changes. There is no disadvantages to nitride other than if the barrel isn't cut right or has burs, it may never smooth out and you're stuck with what you got. My other melonited barrel, YHM47TF, is a tack driver with some good 77 grain. I own both lined and qpq barrels.

http://www.burlingtoneng.com/melonite.html
Link Posted: 2/20/2016 11:07:49 AM EDT

Discussion ForumsJump to Quoted PostQuote History
Originally Posted By StealthyBlagga:


Compared with the $$$ you will waste on aimlessly spraying spend on ammo, the price  differece on the barrel is trivial. I'd just get the cheapest barrel I could and keep shooting it until it keyholes.
View Quote




 
Link Posted: 2/20/2016 1:20:09 PM EDT
What kills a barrel is heat, nitride does not protect the barrel from heat like chrome lining.  

Wear resistance wont matter when the real killer is heat.  
Link Posted: 2/20/2016 2:01:50 PM EDT
[Last Edit: 2/20/2016 2:05:35 PM EDT by Grizbacker]
Thanks for all the replies fellas. Seems that the consensus is still split. I added a poll with the two barrels I have to choose from.

Basically its down to a Daniel Defense midlength s2w profile (heavy profile) chrome moly vandium cold hammer forged with salt bath nitride or a Daniel Defense carbine m4 profile chrome moly vandium cold hammer forged chrome lined. Both are 16". I have heard that mid is better than carbine for rapid fire but wasn't sure on chrome vs nitride.

And yes, I know a bump fire gun is generally just a waste of money but I have extra parts laying around, plenty of ammo, and it should provide for some good times.  
Link Posted: 2/20/2016 2:09:26 PM EDT
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Originally Posted By tirod:
Otherwise all you will read about is how great the chrome lining in the M16 works, because that is all the American shooter knows about.

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yeah the 1919, M2, 60, 240, 249 doesn’t count


Link Posted: 2/20/2016 2:27:48 PM EDT
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Originally Posted By tirod:
Most foreign made issue assault rifles - full auto - are cold hammer forged nitrided,, no matter what.
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I'd like to see production numbers that back that up?
Link Posted: 2/20/2016 3:20:47 PM EDT
I think the differences are going to be negligible. I remember from my mech leaders course that the 25mm cannon on the Bradley Fighting Vehicle has used both chrome lined and nitrided barrels. Both worked well.
Link Posted: 2/20/2016 3:24:27 PM EDT
I'd put a Nitride barrel on a bump-saw.

Why? Cheaper than CL. I would consider my bump-saw barrels to be burners, so I'd probably pick up at least a couple Nitride barrels at a time.
Link Posted: 2/20/2016 4:07:59 PM EDT
I have no data to provide other than I've been extremely pleased with my ballistic advantage barrels
Link Posted: 2/20/2016 5:41:33 PM EDT
Which bbl has the heavier profile?  That will probably matter more than chrome vs. nitride.

That said, I'll take nitride all day.  You probably wont be able to tell the difference, though.
Link Posted: 2/20/2016 5:50:07 PM EDT
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Originally Posted By Eat_Beef:
Which bbl has the heavier profile?  That will probably matter more than chrome vs. nitride.

That said, I'll take nitride all day.  You probably wont be able to tell the difference, though.
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The nitride is heavy profile. The chrome lined is m4 profile. The nitride is also mid and the chrome is carbine
Link Posted: 2/20/2016 5:58:14 PM EDT
If nitride holds up like Chrome does, it's cheaper, and I'm assuming more inherently accurate. Why not go with nitride?



I'm no expert, but I'd imagine that we have modern processes that can make a barrel as easy to maintain and very durable as chrome lining.
Link Posted: 2/20/2016 5:59:20 PM EDT

Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Finslayer83:


I have no data to provide other than I've been extremely pleased with my ballistic advantage barrels
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No doubt about it, sir.




Don't let the "cheap" prices fool you, they're damn good barrels. My mk12 barrel from them shoots way better than I do, and just about 200 dollars.
Link Posted: 2/20/2016 6:54:17 PM EDT
I nitride my barrels simply because I purchase 100 barrels at a time, short chambered. I can then chamber them the way I want and then send out to get nitrided. You can not do that if they come chrome lined. A nitrided bore has sharper rifling and potentially is more consistent. Under severe FA conditions, I think a chrome barrel will hold up better. It is easier to control bore size and consistency with nitride than chrome. I am sure there are a lot fewer rejects with nitride than chrome. With the ease of application, EPA and health issues, that is in favor of the nitride process. I think that is the reason you will see more of it. Craig
Link Posted: 2/20/2016 11:27:32 PM EDT
I don't see the need to obsess too much about the accuracy of nitride vs chrome lining, since most people would be lucky to keep groups to minute-of-barn-door while bump firing.  The same goes for barrel life.  If you can afford enough ammo to shoot out either barrel you can probably afford add $150 to budget for a second barrel and barely feel the sting.  I'd say don't sweat it.  Pick whichever barrel profile you like better and have at it.
Link Posted: 2/20/2016 11:37:23 PM EDT
Nice pull but it should include PRICE because as a 'Bump fire gun' I wouldn't spend over $200 for a barrel for that 'purpose'.

Something even funner... do a PISTOL AR if you don't have one yet. You'll be SOLD on the concept forever.
Link Posted: 2/21/2016 3:37:09 AM EDT

Discussion ForumsJump to Quoted PostQuote History
Originally Posted By faawrenchbndr:


Nitride provide greater Nti wear properties and will be inherently more consistent.
View Quote
Every test I've seen has shown the opposite in terms of durability and round count. The test linked on page 1 by Boeing and a few I've seen from the military.

 
Here's a test don't by military in the 80's that was declassified in 04 (I think) that shows the same. It's a long read but basically there a more durable things than chrome lining, but not practical (certain liners and whatnot), but chrome lining definitely beat out nitriding. Keep in mind, this was in the 80's, I don't know if nitriding is 'better' now than then. I doubt it though. Process is probably cheaper, end result is likely the same.




https://www.dropbox.com/s/spgovduw6r8wu9q/barreltest.pdf?dl=0
Link Posted: 2/21/2016 3:38:58 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By tirod:
Most foreign made issue assault rifles - full auto - are cold hammer forged nitrided, since the 1970s. HK for one. Therefore the track record IS out there on nitride if some research is done. Otherwise all you will read about is how great the chrome lining in the M16 works, because that is all the American shooter knows about.

View Quote
HK does not nitride their barrels, I asked and they said they don't nitrate any of the the 90/G series,MP, pistols or the MR series. The 416 & 417 have Chrome lined bores as does the UMP & G36. The SCAR,ARX,AUG,Austyer,SA80,TAR,ACE,Famas,AK( all variance currently being used ) ,M4,m16, FNC,FAL,F2000,Bren,MSBS,T89,K2,Zastava M2,etc all  currently used by militaries and all have CLB. honestly I can only think of 4 military rifles that don't have CLB. (QBZ- 95, sig 550 , Valmet RK62 and the G3)
Link Posted: 2/21/2016 8:57:08 AM EDT
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Originally Posted By di11igaf:
Every test I've seen has shown the opposite in terms of durability and round count. The test linked on page 1 by Boeing and a few I've seen from the military.    Here's a test don't by military in the 80's that was declassified in 04 (I think) that shows the same. It's a long read but basically there a more durable things than chrome lining, but not practical (certain liners and whatnot), but chrome lining definitely beat out nitriding. Keep in mind, this was in the 80's, I don't know if nitriding is 'better' now than then. I doubt it though. Process is probably cheaper, end result is likely the same.


https://www.dropbox.com/s/spgovduw6r8wu9q/barreltest.pdf?dl=0
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Originally Posted By di11igaf:
Originally Posted By faawrenchbndr:
Nitride provide greater Nti wear properties and will be inherently more consistent.
Every test I've seen has shown the opposite in terms of durability and round count. The test linked on page 1 by Boeing and a few I've seen from the military.    Here's a test don't by military in the 80's that was declassified in 04 (I think) that shows the same. It's a long read but basically there a more durable things than chrome lining, but not practical (certain liners and whatnot), but chrome lining definitely beat out nitriding. Keep in mind, this was in the 80's, I don't know if nitriding is 'better' now than then. I doubt it though. Process is probably cheaper, end result is likely the same.


https://www.dropbox.com/s/spgovduw6r8wu9q/barreltest.pdf?dl=0



You are correct, I had the info backward in my head. Was thinking a bit more about accuracy than barrel life. Just looked through some tech notes about some Bushmaster barrels that are installed on a particular military aircraft. It is indeed chromed.

Current school of thought is that chrome lining is the preferred choice.......who knows what the future will dictate.
Link Posted: 2/21/2016 1:36:20 PM EDT
So how about carbine length vs mid length? I have heard mid is more reliable for bump fire. Any truth to this?
Link Posted: 2/21/2016 2:47:32 PM EDT
you forgot the "pie" button

voted nitride

doesn't really matter, either will do just fine
Link Posted: 2/21/2016 2:49:03 PM EDT
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Originally Posted By Grizbacker:
So how about carbine length vs mid length? I have heard mid is more reliable for bump fire. Any truth to this?
View Quote

Carbine gas is more reliable, mid length has less perceived recoil.  For a bumpfire more recoil is better so I would stick to carbine gas with a flash hider not a brake.
Link Posted: 2/21/2016 4:52:46 PM EDT

Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Grizbacker:


So how about carbine length vs mid length? I have heard mid is more reliable for bump fire. Any truth to this?
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There is a graph I saw years ago that shows you the optimal gas system for length of barrel.




The chart said 14.5" would be best with Carbine length. 16" and 18" both midlength, and obviously 20+ rifle length gas system.
Link Posted: 2/22/2016 9:35:02 PM EDT
Actually the PPT was terrible.  Poorly put together, missing data points, terrible graphs....

But what I got out of it was that we need Boeing to CL our barrels.  Or at least Boeing thinks so.

Standard "Army chrome lining" didn't fare much better than nitride om their testing...but it costs more.
Link Posted: 2/22/2016 11:27:12 PM EDT
I just bought a rifle with the nitride treatment.  I was told by the sales person that the nitride finish is five times harder than the chrome.  For what it's worth.
Link Posted: 2/23/2016 1:18:06 AM EDT


Discussion ForumsJump to Quoted PostQuote History
Originally Posted By ABQ87120:



I just bought a rifle with the nitride treatment.  I was told by the sales person that the nitride finish is five times harder than the chrome.  For what it's worth.
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The salesman definitely lied. If anything nitride is usually not quite as hard as chrome, 5 times harder than chrome is complete BS. I hear people say nitride is around 65-70, but here is a guy testing ak barrels(just normal 4140 & 4150 steel exterior) one of them being nitrided inside and out. The bare 4140/50 is around 25 Rockwell, while the nitrided barrel only comes in around 28. Not even close to chrome, let alone 5 times harder.
I have each, for now I tend to prefer my tried and true bcm chrome lined.









 
Link Posted: 2/23/2016 10:49:50 AM EDT
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Originally Posted By ABQ87120:
I just bought a rifle with the nitride treatment.  I was told by the sales person that the nitride finish is five times harder than the chrome.  For what it's worth.
View Quote


Gun store, and box store counter salesman are just awesome.

Caveat: I know there are still a couple of good gun store guys out there.  They all just left my area many moons ago, and the current batch seem to plague arfcommers, my friends and my family.
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