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Personally, I don't think you were wrong calling the Titan upper a "knock-off" of the HK short stroke piston upper.  There are some aspects that are just that, a copy of the original design.  For instance the op rod assembly.  The one in your Titan went bad so the one from the MR556 was substituted and worked fine.  The things that HK patented like the piston itself, HK chromed and used gas rings.  The DI system also has chrome lining and rings.  Since the HK piston could not be copied the Titan has a fitted piston.  It is my understanding that the HK piston can be substituted for the Titan fitted steel piston.

There is also the Titan rail height, that is giving me fits.  It is my understanding that the top rail on the FF hand guard and upper receiver is 0.065" higher than the HK MR556/416.  Why, again my guess is that HK has patented that.  Yet a 416 hand guard will fit a Titan and the Titan will fit an HK.  I bought a set of used 10.4" 416 sights (the rear sight drum is different from the 14.5"/16" rear sight drum) so I could use the front sight on the HK rail.  I plan to make a custom rear sight base that is 0.065" lower that the 10.4" rear sight.  I'm tempted to bring the sights to a CNC machine shop and have them duplicate the front and rear sight bases.  But that is for another thread.

To me, "HendersonDefense" did not put the Titan upper down.  I think a "knock off" is a much less expensive copy of an original design.  The Titan upper is just that.  I have bought four Titan uppers for far less than the market value of one 416 upper.  If the creators of the Titan were looking to have their upper to rival the 416, it would have a steel barrel with a chrome lined bore.  But instead they used stainless steel.  Why, it would seem to me that is because it was cheaper to use SS.

This is not meant to be put down, but only getting 10,000 out of a MR556 barrel, just doesn't seem that unusual to me.  It is my understanding that cold hammer forged steel is a little tighter grain than a standard steel button rifled barrel.  A steel barrel is just not going to last like a chrome lined barrel.  Chrome is so much harder than steel.  I'd imagine if a plain steel barrel was purchased from the barrel maker that the business normally bought chrome lined barrels from, that steel barrel would more than likely last about as long as the MR556 barrel did.  

If the bore of the MR556 had been nitrided, I'd imagine that the range would have gotten more life from it.  That is why I want to get the SS barrels from the Titan uppers nitrided.  I have found that I tend to get what I pay for.  My 14.4" Titan uppers were $650.  A MR556 upper has a market value of around $1,500.  That MR556 upper plus $200 to get the bore nitrided, doesn't seem worth twice the money or use of a Titan upper.  I hope nitriding the Titan barrel will be worth while.  I'm also tempted to see about converting one of the uppers to use with 7.62X39 and a MGI lower with an AK magwell or maybe a chrome lined 5.56X45 barrel.  Again, that would be something for another thread.



It is my understanding that using a heavier buffer to "fix" over gassing can be that much harder on the op rod system/striker area of the carrier.  The piston system is designed to have a certain amount of energy to function.  If there is too much energy, an extra heavy buffer will slow the bolt group to prevent over function.  But like adding a turbo charger to an engine, if there is more energy in the engine, but the rest of the drive train is designed for a standard power engine, other parts of the drive train are more likely to break.  So if the system is over gassed (too much energy) the extra heavy buffer will absorb that energy, but the system to push the bolt group back to unlock the bolt, that was designed for the standard amount of energy, will be subjected to more energy. So the op rod or the striker point on the carrier can be overwhelmed and fail.  It would seem to me the whole point of the vent on the HK gas block is to vent excess gas to limit the amount of energy the piston receives and imparts to the op rod or the striker point system.  That is something I am looking into for my Titan uppers.  YMMV.

Scott

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It took almost seven weeks for the two 10" uppers I ordered.  Keep the faith.  So far as I know, everyone that has ordered an upper has received it.

Scott

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thanks guys. I hate to be a worry wart, and I suppose there is not telling until I get back and check things out, but I cant help but stew. Has anyone had a good experience with the 10 inch uppers on GB? I felt like I had a good vibe on them but now I feel like most guys are having problems. I mean, it was about half as much going with the titan as opposed to modding a used MR556 upper... but now im thinking "buy once cry once"... I suppose we'll see, for all I know the thing will run like a top when I get back, otherwise it sounds like its going to be a hell of a project gun...

thanks again for all the input. fingers crossed until I can run it in January.

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As fivepointoh already pointed out, the chome lined MR556 barrels are for European commercial variants, and have not, to my knowledge, appeared in the U.S.  



Even if they did, while it would be a step in the right direction, a chrome lined MR556 barrel is still not an HK416 barrel, and you still need to get it cut down and reprofiled.  I know that barrels have been cloned in ones or twos, or even small batches, but they are not anything resembling "available."  



Sure, it would be awesome if H&K USA would sanction just selling the MR556 with an HK416 (or HK416-esque at least) barrel, but I don't see that happening in the near future, though chrome lining may be more of a possibility.  



Not that it's too hard to get the barrel cut down and reprofiled, but it's a hassle that, from what I can tell turns a lot of people off to even bothering.  This then keeps both MR556 and "true" HK416 upper prices up.  



Given what people will pay for a SCAR-16S, I suspect if you could put together a respectable HK416 clone for right around $3,000 using off-the-shelf components, there'd be a lot more people getting them ("sale" and Gunbroker prices of MR556s in the $2,400-$2,500 range, leaving $500-$600 for a barrel assembly, which is still not cheap...).  



~Augee