Here's an idea. If DT is reading this, send one of your rifles off to Battlefield Vegas.

See how it holds up there.

The PSA Premium guns are holding up the same as the Colt guns, yet people call them trash.

Let's see if it can hold up as well as a $600 cheap AR.

I dont think DT changed anything other than the gas plug and extractor.

The MDR would recoil itself to death under full auto fire...I think at the price point charged...can it beat the 125K+ round fired SCAR...no chance

Thanks guys for your comments.

They're not replacing the barrels. I mistakenly thought they were changing out the whole extension. Apparently the "case support" is sandwiched behind the barrel by the extension. It surrounds the case head and has reliefs for the extractor and lower bolt lugs since both protrude from the bolt face. It needs to be replaced by one with a wider relief to accommodate the new extractor.

I doubt they put the new barrel extensions (which are different to clear the extractor, unless something changed) on the old barrels.  Like I said, I have to wonder if there's something subtly different about the chamber than before.  I thought several users had found them to be a bit on the tight side, using Cerrosafe as a casting material?  Combine a tight, sticky chamber with a very short, lightweight gas system with lots of dwell time for that full-length barrel...it's a recipe for a gun that fights itself during the extraction cycle.  The low mass of the moving parts can simply be brought to a halt too easily by all the energy that's lost, and even if you do drive it hard enough to overcome the sticktion, unless you nail it *just right* you are now driving the carrier to much higher velocities than needed (which we have to assume plays hell with that special extraction mechanism at the end of bolt travel, as well as just generally abusing the receiver parts).  Simply having enough extractor to overcome that sticktion won't help reliability for long; you'll just start seeing other parts wear & break instead of disposable case rims.  Like trying to knock a croquet ball from beneath your foot's pressure with a very hard hammer, while precisely controlling how far it will roll; very tricky, and impossible if you figure in the variety of ammo you have to contend with.  A looser chamber with a more generous throat/leade won't be as accurate, but it will allow cases to extract more easily (and it's not like the MDR can take advantage of the barrel's mechanical accuracy anyway).  If that's indeed what made the difference, that's really good info to know, for a variety of reasons.

ETA: Disregard, apparently.  I now suspect we'll start seeing medium-round-count failures in MDRs with these upgrades.  The instant you crack a stuck case loose, there's nothing resisting the force you've applied to do so; unless your gas pulse is *just right* to break the case loose & not impart a huge amount of energy to the op-rod, you're unavoidably accelerating that BCG faster than it was meant to be.  No way the receiver & ejection chute components hold up to full-on abuse long term.  Remember, that's why there was an adjustable gas system in the first place; to avoid battering the BCG against the rear of the gun.

I wonder how many poor scopes that gun killed...

So there's a spacer ring/block between the extension & barrel, sort of like the MPX or earlier 'Moleman mod' for DI 9mm ARs?  That's just screwy.  Wouldn't that make the extension lugs cantilever quite a bit more than is necessary?  Why not simply machine the 'case support' into the extension?  Why's it even needed for a case as long as the 308, and without a plunger-ejector trying to push the case out into the side of the extension?  I'd love to see some good close-up pictures of that assembly, I'm sure there's a good reason for that added complexity.

This is what I've been preaching about the MDR's problems...

The Scar 16 isn't an optic killer...the 17 is...but as long as you get SCAR approved mount or an elcan you'll be fine.

Given how the barrel is designed, yes, it does need to be sent back as it is more than just changing an extractor.  See Carolina's First Defense's posts for pictures of the new parts that were used in the upgrade.

Carolina's First Defense FB Post

DT outsourcing the repairs now? Are they having that many returned for the "upgrades"?

No, they're one of DT's larger dealers and were granted permission to do the upgrades locally for their customers.  At the time, the turnaround for the upgrades could be 3-4 weeks, but CFD was able to do it within a matter of hours since the volume was much lower.

DT tries to do something to help their customers and it gets spun into some nefarious plot.  Sometimes a cigar is just a cigar.

Maybe it's one of those exploding ones from the Marx Brothers movies?

Nothing in my post indicated anything about a "nefarious" plot, your bitterness and victimization attitude has you seeing things that aren't there. And don't start with the whole "after twelve years of personal attacks.........................

Call it a preemptive intervention...given how negative you are regarding the MDR, I take *everything* you say not only with skepticism, but in the worst possible manner because that's usually how you mean it...before scurrying back to play innocent.

And this has gotten way past any sort of tech discussion...well done.

JFC

I've got no skin in this game, but you've been white knighting this turd since day one...

I wanted it to work out, I really did, but I've moved on.
Everything I've seen here makes me glad I kept my RFB.

If they're simply spinning off the extension and clamping it down over a new ring (is that how it works?) then there's little reason others can't do it just as well, so it's good they are seeking some help.  How are they controlling headspace, is the extension just torqued into position & orientation by clocking the threads to eachother?

I'm still having a hard time visualizing what that ring is doing; there's few pictures of the breech out there, and I sure can't recall that level of detail from messing with one at SHOT.  I thought it was basically just a "deeper" AR-style bolt head & extension, with a slot milled through the deeper "cup" for the case to slide across.  It's got reliefs for the bolt protrusions, so it's basically just taking up space in there?

Pretty much seems that way.  Filling in all the area behind the locking lugs except where the extractor and bottom lugs need to sweep during bolt lock.
The ring on the spacer goes around the reduced diameter on the barrel.

I must admit, even though it is extra parts it was very foresighted for DT to design the barrel this way to allow for future improvements/upgrades of their system without having to replace the entire barrel. Is this something carried over from their bolt guns?

I have a feeling it was more along the lines of:

"Crap, we have a problem and need to improve extraction.
What's the cheapest fix? What's the cheapest part we can replace"

I think they made the biggest change they could without getting into the barrel or extension.

I could be wrong

What I was trying to say is that the design of the ring on the barrel turned out to be a brilliant design as it allowed them to upgrade/improve percieved extraction issues without changing the whole barrel. Ingenious foresight!

It sure looks like it's just a feed cone...I guess this way maybe the barrel is easier to make.  Kinda weird that you'd need bullet guiding features that far into an extension that already has a guiding cone further back.  I wonder if it is really necessary, or just a mechanically pleasing feature.

New "military" cold weather testing video of MDR shows two out of the three contact points are actually heat-sinks.

Appears to be civilian testing not military.

Cold Weather Testing

MDR has passed NATO testing. Shut your mouth.

I got my RMA Friday and will be sending my rifle in on Monday or Tuesday to have all of the improvements done.  I got my Silencerco muzzle brake and ASR mount the other day so when I get it back I will throw some lead down range hopefully.  I think they are doing a good job at listening to peoples problems and suggestions and addressing them.  The added lifetime warranty adds peace of mind and according to the FB owners page most people are happy.  I think the brittle plastic may be over blown as I have only seen a couple people with issues, I'm sure there are more but I don't see it being a big issue.. if mine shits the bed then I will have a different opinion, lol.

Hope it all works out for you.

No
Additional
Testing
Ordered
- Nick

From the pics above...it appears the new extractor is not MIM...I don't see casting marks...can someone confirm?

If so, wonder why Nick and the gang at DT abandoned their highly claimed MIM extractor...

What's with the General Grievous mask?  That's like page one of "How to Make Friends and Make People Not Take You Seriously"

I, too, think the plastics issue was overblown*, but the few reports of cracks in the takedown pins is almost certainly the result of excessive recoil needed to make the gimpy guns run correctly (and I still don't see how a stronger extractor could possibly improve that)

Hun, the reason they extractor is machined, if indeed it is, is probably because they don't want to blow another 25-30 grand on tooling until they know it's an actual fix.  MIM --even Indo-MIM-- is a perfectly legitimate production technique these days.  Allegedly, when it's done right, it's slightly stronger & more consistent than bar stock  ('billet' in the gun community) because the powder production requires a higher quality feed stock with fewer inclusions/impurities, and they claim porosity levels on part with bar stock.  Now, still not as good as forging (since forging closes up the few voids that are present and arranges the grain boundaries along advantageous paths) but I'm not sure how common that is with any new-production small parts these days.  No need to complain about a perfectly acceptable modern production method; it's like bitching about how the SCAR is extruded & not machined from bar, and therefore will warp/etc when it gets hot.

*The MDR seems no less 'flimsy' than any other polymer-heavy gun I've handled, including the Tavor, ARX, FS2000, and of course RDB.  It's the nature of the beast, unless you really do want something so rigid it shatters in cold weather.  Oddly enough, you never see people complain about how flimsy the Tavor/X95's furniture is, but rather the opposite (I swear the owners of those guns must live in an alternate reality or something, where it's as reliable as an AK, as nice as a B&T, and as adaptable as an AR)

Trust me, very familiar with modern MIM and manufacturing...it can be very good if done right...its worthless when its not. I was just surprised that DT would go solid steel after making countless upon countless claims how their MIM part is better...so the new upgrade...in their words...wouldn't be up to their standards...just saying...DT said during their testing the MIM part lasted longer than the bar stock steel...I much prefer bar stock steel in an extractor over MIM...but I am just stating what DT has fed us for years about their MIM parts.

At the end of the day. In today's manufacturing capabilities...its all about the quality and the controls in place.

The problem is (and it's not only with this company) is that companies are in such a rush to push a product out that they're allowing the customer to be the guinea pigs for the T&E of their products.  This rifle was released more than a year ago and it's still on the slow crawl to getting to where it should've been on release day.  This practice by companies is unacceptable....

Don't even try and say they did any testing of this rifle before release because there's no way in hell.

People in leadership started reading this book: http://theleanstartup.com/

Misinterpreted it to the 10th degree...and we get what we get now with products across many industries...its all fine and dandy...as long as you have the support nailed down from the start...which DT, and others did not.

Early on DT blamed us remember for every single issue...it wasn't until GT and InRange, with their audience base, publicly shamed DT essentially for releasing junk. If it wasn't for forum push back and YT...DT to this day would still probably blame the customer for rifle troubles...their service department seems to be good...which was/is their saving grace. I think finally we are saying functioning rifles...question is how long will they last...

In what respect?

From what I've read on here and elsewhere...is their service dept perfect...no...but overall I think they get a pass...the service dept.

If you have different thoughts as to why not...share...

I know the service department isn't where design issues get fixed, but it seems like most of the MDR's that are sent back get sent back multiple times, with various degrees of band-aids applied, or "we couldn't duplicate the issue" or "try different ammo".

Well...true...the 2019 gas plug is just over-gassing the gun more to aid in extractor...vs an actual fix...like extending the gas port and loosening the tolerances on the chamber...

Clearances, for God’s sake, man...

He's not wrong.  Loosening the tolerances doesn't help unless the chambers are cut to the larger end of the tolerance.
Increasing the clearance makes the nominal dimensions larger.

Tolerance is how tightly you are controlling a dimension.
Clearance is how that dimension interacts with the mating part, in this case, the brass and bullet.

Yeah just opening up tolerances is usually bad and can result in tolerance stack. One part at high end of tolerance another at the low and then bam they don’t work together. Or with the chamber as the gentleman above me is alluding to high end on a chamber and then it’s looser low end of expanded tolerance the Chamber would be tighter than ever.

Lighten up, guys, it's a super-common mixup like loose/lose.  I'm just being a D&T Nazi (annoying relative of the Grammar Nazi)

Where the MDR is concerned, I'm not sure "lighten up" is possible.  

Yeah, it is kinda heavy for what it is...

It is. With some of the durability issues already or would be hard to take more material out. Definitely not in the BCG or op rod.

I finally got around to sending my rifle back to DT this past Thursday for the upgrades.  I actually never shot it but I am hoping to get a fully functioning and up to date rifle upon it's return.  Time will tell.

Plus even with the bulk it’s added since it was unveiled, every video I see looks like it has the recoil of a 12 gauge. I don’t think lightening it up would help.

I still say the reciprocating mass is far too light, and the rifle is gassed to move way too damn fast to overcome issues with the ejection chute. They're all probably going to beat themselves to death right along with the shooters' shoulders.

Yep...but no one wants to admit this fact...except a select few.

If you look at the BCG...they could have left 2-3oz of material on their no problem...