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Discussion Starter #1 (Edited)
Alright folks, For those who care, or for those who just want another topic to yell at me in, here's the update on the nitrided parts.

The parts came back from H&M nitriding today. They look frikken fantastic! Nice dark black. They've been oiled so I can't tell how flat or matte it is until after i've degreased. I'm torn at this point if I should leave them as is or parkerize the parts for the flatter black look. Yes, it's easy to parkerize over nitriding and doesn't hurt he nitriding at all. Glock did it for years on their slides.

THe parts sent were the barrel, gas block, barrel nut, bolt, carrier, extractor, firing pin, op-rod, op-rod retaining sleeve (these two were a bitch to seperate without damaging them but I succeeded), and a knights match trigger setup.

All of the proof marks are still visible (although not as contrasted as they were prior to nitriding), and even the laser engraved HK logo on the carrier is still visible in the right light.

Prior to sending in the parts, I had several telephonic conversations wth the fine folks at H&M Metal Processing and they informed me that the nitriding process would not be adversly affected by previous parkerizing and that the nitriding would go right through it. Since I did the profile work on the barrel, it was sent in blasted, whereas the bolt, carrier, etc. were sent in with factory parkerizing. To be honest, I can't tell the difference in finish between the parts that were nitrided in the white or with parkerizing. They look and feel exactly the same. I'm very impressed.

The crown that I so painstakingly machined on the muzzle is now preserved for quite some time. It was pretty before, now it's beautiful. For clarification, after cutting the barrel back to 14.5, I did a standard crown with a common lathe bit, and then placed a machine bit of appropriate size in the centering mandrel and did a 5mm counterbore. The use of the machine bit created an very precise 90 degree crown with no burrs or abnormalities due to the slow rate of feed and the use of a brand new bit.

About the KAC trigger: It's common knowledge that Knights match triggers aren't expected to last over 3 to 5 thousand rounds, even by the manufacturer. We'll see if nitriding them increases their operational life. To be honest, after all the research i've done, I expect this trigger to last my lifetime, my childrens lifetime, and even longer now that it's nitrided, but we'll see. If they don't, no biggie, putting them in the box didn't cost any extra when I sent them in (H&M has a $200 minimum order).

I'll try to get some pics of just the parts posted up before I finish the project here later this week. Before and after pics methinks.
 

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I'd be interested in pics.

On another note... we had a discussion about gas port hole in the barrel in the grooves. Might have been vaperware. The few barrels that I scoped that had them were "lucky" picks apparently. I just checked 20+ 10.4" barrels and only 2 were actually in the groove. I also checked several G36 barrels and only one was in the groove.
 

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Discussion Starter #3
Interesting. Thanks for the update on that.

Neat thing about H&M nitriding is that they do a full ultrasonic cleaning of parts prior to dipping them. So any fouling that I couldn't get out of the gas port(what little was left if any after how thoroughly I cleaned the parts) was removed and the gas port is nitrided as well.

This should keep gas port erosion controlled for a very long time.
 

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Grumpy, did the extension still have 150ft-lbs of torque on it? That is my only concern with the Nitriding process, as the temperature of the salt bath could cause the extension thread to swell and when cooled lose torque. If not, you have a superior weapon that will last forever.

Look forward to seeing it!
 

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Discussion Starter #5
Grumpy, did the extension still have 150ft-lbs of torque on it? That is my only concern with the Nitriding process, as the temperature of the salt bath could cause the extension thread to swell and when cooled lose torque. If not, you have a superior weapon that will last forever.

Look forward to seeing it!
To be honest, i'm not about to "test" if the extension is still at 150 ft-lbs. Not worth it to me if it comes un-done and I have to hope that a re-torque remains correctly aligned.

I've heard about those issues as well and specifically asked the guys at H&M if this would be an issue and they confirmed that it wouldn't. Were they just some nitriding company, I might be weary of their answer, but H&M does a LOT of gun related work for some of the biggest names in the industry and they have the experience to do these things without screwing it up.

To be honest, one of my concerns was that the extractor retaining nub in the barrel extension would come out during the process due to simply being pressed into place (that I could see), but it's still in and solid as ever.


To be honest, i'm as giddy as a schoolgirl right now........ ;-)
 

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Alright folks, For those who care, or for those who just want another topic to yell at me in, here's the update on the nitrided parts.

The parts came back from H&M nitriding today. They look frikken fantastic! Nice dark black. They've been oiled so I can't tell how flat or matte it is until after i've degreased. I'm torn at this point if I should leave them as is or parkerize the parts for the flatter black look. Yes, it's easy to parkerize over nitriding and doesn't hurt he nitriding at all. Glock did it for years on their slides.

THe parts sent were the barrel, gas block, barrel nut, bolt, carrier, extractor, firing pin, op-rod, op-rod retaining sleeve (these two were a bitch to seperate without damaging them but I succeeded), and a knights match trigger setup.

All of the proof marks are still visible (although not as contrasted as they were prior to nitriding), and even the laser engraved HK logo on the carrier is still visible in the right light.

Prior to sending in the parts, I had several telephonic conversations wth the fine folks at H&M Metal Processing and they informed me that the nitriding process would not be adversly affected by previous parkerizing and that the nitriding would go right through it. Since I did the profile work on the barrel, it was sent in blasted, whereas the bolt, carrier, etc. were sent in with factory parkerizing. To be honest, I can't tell the difference in finish between the parts that were nitrided in the white or with parkerizing. They look and feel exactly the same. I'm very impressed.

The crown that I so painstakingly machined on the muzzle is now preserved for quite some time. It was pretty before, now it's beautiful. For clarification, after cutting the barrel back to 14.5, I did a standard crown with a common lathe bit, and then placed a machine bit of appropriate size in the centering mandrel and did a 5mm counterbore. The use of the machine bit created an very precise 90 degree crown with no burrs or abnormalities due to the slow rate of feed and the use of a brand new bit.

About the KAC trigger: It's common knowledge that Knights match triggers aren't expected to last over 3 to 5 thousand rounds, even by the manufacturer. We'll see if nitriding them increases their operational life. To be honest, after all the research i've done, I expect this trigger to last my lifetime, my childrens lifetime, and even longer now that it's nitrided, but we'll see. If they don't, no biggie, putting them in the box didn't cost any extra when I sent them in (H&M has a $200 minimum order).

I'll try to get some pics of just the parts posted up before I finish the project here later this week. Before and after pics methinks.
Completely unrelated to HK....any particular reason as to why you had the KAC trigger coated? If I am not mistaken they are coated from the factory and since they are not expected to last longer then roughly 5k rounds what's the use? As you want real world experience I have had 1 sheer the hammer which is normal on a SR15E3 with 2760rds and I have seen 2 more break during shooting.
 

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Completely unrelated to HK....any particular reason as to why you had the KAC trigger coated? If I am not mistaken they are coated from the factory and since they are not expected to last longer then roughly 5k rounds what's the use? As you want real world experience I have had 1 sheer the hammer which is normal on a SR15E3 with 2760rds and I have seen 2 more break during shooting.
KAC says they're only good for about 3k. Mine did make it anywhere nearly as far as yours, PSG
 

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KAC says they're only good for about 3k. Mine did make it anywhere nearly as far as yours, PSG
Well then mine was close to its life expectancy. I was told 5k by one of the Magpul guys..oh well. The KAC triggers are nice for what time they last but it sucks to know the trigger in your 2k(E3) or up to 28k (If SASS) rifle will fail you in less then 3k rounds. All of my rifles have been converted to Geissele triggers so no big deal. That being said to drag this back to HK content is there any added benefit if any to having the op rod coated?
 

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The only nitrided part I have is a new RCM HK 93 barrel but it is a pretty impressive finish IMO. I would call it a semi gloss black. The 93 build I am going to have Ghillie do will get a Vietnam Tiger Stripe ceramic finish..
 

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I have done quite a bit with H&M, they are local, and at this point any bbl goes to them prior to build, even the PSG1 and MSG90 bbls in recent builds. All my bolt and non-HK guns get the treatment, just no reason not too.
 

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Agreed, Nitride treatments are a phenomenal way to get that extra hardness and a sleek look on treated surfaces. I would love to see the MR556 parts that you had done.
 

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Discussion Starter #13
Completely unrelated to HK....any particular reason as to why you had the KAC trigger coated? If I am not mistaken they are coated from the factory and since they are not expected to last longer then roughly 5k rounds what's the use? As you want real world experience I have had 1 sheer the hammer which is normal on a SR15E3 with 2760rds and I have seen 2 more break during shooting.

I'm hoping that by nitriding, I can get the trigger to last longer then the factory expected 3k to 5k range, and make my investment last longer. I do not believe they are nitrided from KAC. I can tell you that the difference in finish now that it's back is very noticable from what it was prior to nitriding.

And, like I said, since it didn't cost any more to add it to the batch, why not?
 

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Discussion Starter #15
Dear God, please make me into a bird, so I can fly far, far away, and then go back in time and crap in the eye of the douche-canoe who invented peel washers.

I got the hard part done today and got the bi-lock pinned and welded. After welding and contouring the weld, I parkerized the entire barrel assembly and it turned out fantastic.

The full assembly will take place tomorrow and then i'll post pics of the nitrided parts before and after the build.
 

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Discussion Starter #16
is there any added benefit if any to having the op rod coated?
Missed this earlier.

THe primary reason I put the effort into dissasembling my op-rod and having both it and the sleeve nitrided was for the corrosion resistance aspect of nitriding. But, turns out that the high natural lubricity of nitriding also decreases friction and makes the op-rod compress easier with less binding.

When removing the spring retainer sleeve from the op-rod, it was a difficult task, especially without damaging parts. I was very careful about it. When re-assembling it today, I noticed that there was a lot less friction between the parts an it went back together with much less effort then it took to take it apart. I'm happy with it.
 

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Grumpy,

How do you go about getting this work done by H&M? Can you send parts directly to them, and do they have any price sheets available? I'm curious what it would cost to have an Hk pistol barrel and slide done with this process.

Can't wait to see pics of the work they did on your MR556!
 

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Grumpy,

How do you go about getting this work done by H&M? Can you send parts directly to them, and do they have any price sheets available? I'm curious what it would cost to have an Hk pistol barrel and slide done with this process.

Can't wait to see pics of the work they did on your MR556!
Good idea for a pistol barrel. I may want to do that too.
 

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Discussion Starter #19
Grumpy,

How do you go about getting this work done by H&M? Can you send parts directly to them, and do they have any price sheets available? I'm curious what it would cost to have an Hk pistol barrel and slide done with this process.

Can't wait to see pics of the work they did on your MR556!
I found their website and actually called them to find out what they charged, etc. They do not have a price list for individual customers that I know of. I was told they have a minimum order of $200, and when I asked if I could send in my Sig P226 (triple serialed W. German marked) in the same order, I was told that it would be $300 if I did. I just went with the $200 order right now, but I am putting together another package to send to them and i'm going to find out if I can send in the 226 and a bunch of steel G3 magazines in the same order and stay at the $200 level.

When you call them, ask for "Shade". He's the guy who handles these sorts of orders. Nice guy and very helpful. When sending the parts, be sure to specify which process you want, either straight SBN or SNB QPQ. I went with QPQ for various reasons.

I have also been thinking of getting together with some friends and doing a bulk order. With a minimum order of $200, and with it getting less expensive per part the more you have done, it would work out to be pretty cost effective to make a larger order and people would end up paying a lot less for their parts to be treated then if they did it indiidually.

Also, the $200 covered return shipping as well, so in all, with all the parts I sent in, I got a hell of a deal anyway as far as i'm concerned.
 

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Grumpy,
I can't wait to see your pictures. I'm sure you listed this before but what profile did you go with? Something HK offers or custom? Did you use a CNC or manual lathe? Hopefully you have photos of your receiver/barrel fixtures/tools, etc. I know you said you milled clearance cuts in your receiver blocks.

Exciting to follow your project!

TC
 
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