This reminded me of one of Nick's answers in the bpf q&a thread.

15.   In general the piston/ plug chamber volume seems on the small side.  There's been quite a debate about the effects of this on the chamber dwell time in the MDR.  While shooting 168 gr and higher I have seem a steep increase in pressure signs and torn rims.  This seems to be a problem other users are encountering. I'm curious if this is a result of the heavier bullets on the dwell time of possibly a chamber issue? What would you recommend?

a.   We experimented with the chamber diameter, it did require a larger gas hole to cycle the rifle with a bigger chamber but it did not change the dwell time.  The current gas-block location and chamber volume is very similar to that found on the FN Scar Heavy rifles.

As does their ACE 308 pistol; it's like halfway between the 'SAR' intermediate, and the 'MAR' super-shorty pistol length used for the other chamberings.

You would be surprised how much 'starting volume' changes the dynamics of a gas system.  An old trick in the AK crowd was to drill a blind hole into the face of a piston when a gun was running overgassed, as an intermediate step before slotting the sealing surfaces.

I did that to my SLR106CR...worked like a charm.

GarandThumb's Review ...

That was actually a little worse than I expected. Wow.

I think it's gonna be hard to scream bias or stupidity on that one as well.

Ouch. I was expecting it to go poorly, but not like that.

I'm honestly surprised he had ejection and chute related malfunctions and no mention of having to knock stuck cases out.

Yikes, that review was as professionally done as one could do given the circumstances, and yet the takeaway was do not waste your money on this POS.

Scathing in the most unbiased manner. That'll destroy the MDR long-term.

Right, most YouTube reviewers (in general, not just the gun world) are so exaggerated and speak in hyperbole. OMGITSTHEWORSTEVAR!!!1! Where here GT was going pretty far out of his way to speak precisely and professionally. Several times I got the impression he was trying to speak politically or even nicely, while still trying to balance that with his honest assessment. It was kinda awkward at times to watch.

To me the greatest part of the video was when he introduced the "gunk" test...it failed...then he threw a SCAR, DD and a pistol into the same gunk...all worked...

DT needs to stop the production of the MDRs immediately and remedy the situation while they still can...if they go about business as usual from this point on (meaning telling us how awesome and flawless it is)...they will fail.

The gun failed with TRUE, M80 milspec ammo...plus with the ammo that DT provided for GT to run...along with all the latest updates...still failed...failed with the cover off...

DT it is TIME TO ACT...recall it...and fix it...it is 100% obvious that the new gas plug, bolt head with wider extractor is NOT THE SOLUTION...nor is taking off the chute....

When at the end of the video GT recommends to save money and spend it on training instead...that should be the sign for DT to stop monkeying around....

The more I think about it...

His mud wasn't test wasn't calibrated to DT standards. If he had used the proper test the mdr would have functioned perfectly while the scar, DD and m17 failed.

Just like a trigger pull gauge, our d*mb*ss MDR owners don't know how to use mud correctly, so those results are invalid.

Yea, I trust Mike's opinion 100%.  He puts 1000s of rounds through these guns before he tests them.  He also puts his gear through the ringer with his job so his recommendations are pretty spot on.

Well you know...in DT's testing environment (back of a warehouse) the MDR runs fine...well over 15,000+ rounds .... if anyone believes that crap anymore is a fool. The MDR was never thoroughly tested...its quite obvious...

But muh MDR passed NATO testing!

The "thoroughly tested" ship sailed long ago for me. Pretty sure it finally slipped below the water when Nick came out blaming the in-range failures on ammo.

Not
A
True
Organization

Maybe he meant UN standards

As in unknown?

DT MDR     shame...it could have been a great rifle....

Dang you turned a corner. You were so hopeful and optimistic, not as much as a select few but still. Lol

Man...I would have had a MDR a long time ago...if it would have been proven to perform reliability on a normal setting with M80 ball...hands down...would have...without a question...

Originally sold my Tavor to fund one...I am right back into a Tavor SAR...got tired of waiting...my only hope now for a 308 bullpup is the Tavor 7 (or if Keltec would design the RFB with SR25 mags)...or a completely different MDR...say...MDR2.0...

I mean ... in all seriousness ... how on earth does DT expect people to say ok ... I will give $2500 bucks and spend ridiculous amounts of ammo just to see if it would finally work ... not sure if many will take that risk anymore with it.

Glad some have found sustained, reliable function...but even those people have had to DIY modify the $2500 gun to some degree..which should never ever never ever should be needed...at that price point...

https://www.instagram.com/p/BsGjVoPl25B/?utm_source=ig_web_copy_link

I had the side chute issue similar to GarandThumb, but only with Federal XM80C out of eight different brands I've fired, including Silver Bear.

I sincerely hope these two very public failures spur DT to take a hard look at the issues and fix this; I really want my MDR to work properly and have been holding off making any tweaks to it hoping they'd rectify everything with a factory fix.

Serious question on this has anyone ever found any documentation on nato testing of small arms? Like a list of tests how they are performed how many units in the test for a proper sample size etc? Any beaurocratic multi state body like that should surely have that written out (in multiple languages even) if it does in fact exist. I remember a few years ago googling to see if f I could find anything to no avail.

My current belief is that no such thing exists and it’s more a paperwork thing for a nation to get nato stock numbers on small arms than anything else. Therefore when a company boasts about such a thing they are being less than truthful. There are some standard rounds so Uncle Sugar can provide easy resupply on ammo and then it’s free game for weapons and magazines. Even then some nations blow off the standard rifle round thing even. Example the Czechs joined nato in 99 and still haven’t fully gotten rid of their 7.62/39  vz. 58s for the Brens yet unless I’m mistaken.

Lastly of course the MDR doesn’t function after encountering water it’s a desert technology

This is the US military, which I believe mirrors NATO testing https://apps.dtic.mil/dtic/tr/fulltext/u2/a481861.pdf

Now NATO has the requirement: NATO, 2001. NATO AC/225 (LG/3-SG/1) D/14 and NATO AC/225(LG/3)D/7 as well as TPVD 637-81 but I cannot find a copy of it.

Czech have long gone moved on from the Vz.58s...Hungary (joined NATO in 97) also just recently adopted the BRENs over the AK-63D and AMD-65...I believe NATO requires a switch over once their former firearms go end of life...for their standard army...now most NATO countries and their SF units switch over to NATO 5.56/7.62 weapons fairly instantly once joined...I know Hungary received a shipment of M4s and other US/German/Austrian small arms for their SF and TEK.

Recently...Hungary adopted the KAC M110 as their DMR...

Didn't do so well in the desert for in range either though.

Should someone try a review in a tropical climate maybe? Or go full retard and test in the Sahara?

Thank you for the numbers im looking into them as best I can. I don't think its safe to assume the US test mirrors nato tests. If documentation of that could be found that would be great then we'd have a list of all the tests anyone making those claims of passing a rifle through such a testing scheme is claiming their rifle can handle.

I'd argue the long gone part since the bren adoption has been slow and there was the whole 5.56 ak they developed early on after their break from the USSR and its eventual demise that went no were from lack of funds but yes all countries do seem to conform eventually which makes sense since member countries are supposed to standardize what they can.

So far found a nice presentation the Army made for im guessing schooling logistics folks on NATO interchangeability rules. Mostly focuses on ammunition.

Part about ammunition that makes me raise the BS flag again to private companies making claims of them submitting their stuff for nato tests. To be fair this is ammunition standards though and not small arms themselves.
https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2011/smallarms/WednesdayInter12315Pellegrino.pdf
"It is NOT possible for manufacturers or non-NATO nations
to independently submit ammunition for NATO Production
Testing"

pgs. 19 - 24 are interesting because they dust over Nato Nominated weapons aka members weapons that ammunition must function in for it to get approval.

not really relevant but the timeline on pg.27 is interesting. The bulk of the standardization efforts have happened post cold war on it. Which seems strange since NATO has lost most of its purpose since then. Though it could make sense financially since most members have stripped their militaries to the bone since then and making sure everything is standardized means when they send a token group of servicemen out they can fully rely on US logistics.

NATO is also a huge political statement as well as its functional purpose. Example state department release on states open to nato membership from 1997.
https://1997-2001.state.gov/regions/eur/fs_members.html
"NATO membership is potentially open to all of Europe's emerging democracies that share the alliance's values and are ready to meet the obligations of membership.
There is no checklist for membership.
We have made clear that, at a minimum, candidates for membership must meet the following five requirements:
--New members must uphold democracy, including tolerating diversity.
--New members must be making progress toward a market economy.
--Their military forces must be under firm civilian control.
--They must be good neighbors and respect sovereignty outside their borders.
--They must be working toward compatibility with NATO forces."

So you are right about them having to be migrating to more NATO compatible systems I wouldn't doubt that id just point out that politically that means they can take their sweet time about it especially with the militaries being under democratic civilian control parts being listed before compatibility.

Lastly I hope this didn't come off argumentative that isn't my intention. Hopefully more people will dig into this and we can get even more information. Lots of interesting info in a tech forum thread is always good. Especially one thats gone on for 54 pages and is mostly speculation and jokes including horrifically bad ones from me .

Oh no...not at all...NATO is just...well..confusing if you aren't in it...

Now...the US drives many NATO requirements......NATO AC/225 is the standard testing procedures (there are several within the AC/225 designation)...but I cannot find a single piece of PDF file online about it...

However...looking at DT's drop test video...it mirrors the US file I posted...

I did some searching on the NATO website and gave up after I found links to the documents but was denied because they were "secret" or some such nonsense and not available to non-state level requests.  I'm sure they're out there, but I washed my hands of searching at that point.

I'd like to see them do a test based on the test the Swiss did on the Sig 550

http://www.biggerhammer.net/sigamt/550/550techinspection/

FIFY

I have a test I wish the mdr could pass.

Go to your local sporting goods/hunting store. Buy a box of each type 308 they have on the shelf. Dump them in a bucket and mix. Load a mag and run through it without failure.

my only exception is steel cased ammo...

Standards might be a little too high there.

On the plus side, at least they can say they shipped rifles out.

I'm pretty sure my inferior Mws and even the RFB and Armalites I've owned could pass that test. I'll have to look and see what kind of commercial ammo I still have.

I used to have 2 ptr91s that could do that easily with $1 surplus mags, including Tula.

You know...my LMT MWS runs any "junk" ammo I throw at it...it is quite a pleasant experience...

Well it's a junk rifle so of course it's going to run junk ammo.

Oh yeah. Forgot.

Every .308 / 7.62x51 rifle I've owned would run anything I fed it. Even the worst of the bunch, a Century Arms FAL.

Century Arms FAL

HK 91

DSA FAL

DPMS LR 308T

M1A Scout

M1A Nation Match

All ate factory .308 , every kind of Surplus NATO available, and Wolf. None of them ever had any issues feeding anything, ever.

None were over $1500.

There's no excuse for a $2500 rifle to have any issues at all, period.

If this MDR can't be reliable with all ammo right out of the box when you get it home, it's not worth spit, and the owners should be given full refunds. I would never put up with that bullshit at any price over $300.

If you have the bandwidth prepare for much detail and information overload:

DT announces .223 MDR initial shipment.

Would have thought this would be a bigger announcement with more fanfare.

Same, and if it couldn't, I either didn't buy it in the first place, or sold it. Any in-spec 7.62x51mm ought to run any in-spec 7.62x51mm gun... or something is massively wrong.

Well, they probably don't want too many pissed of 5.56x45mm guys... it's bad enough with all of the 7.62x51mm guys pissed with them over the MDR.

Hey, who knows... the bolt velocity/mass might be more suitable in 5.56x45mm. The gun might actually run, in that case, and only be a thousand dollars and three pounds more than the Tavor.

Did they ship with the ejection chute or not and a list of approved ammunition?

More than likely not...there is hope as the 5.56 a lot easier to work with...if it doesn't function...they are dead in the water.

World’s first 5.56 bullpup with an unavailable but non-functional caliber conversion to 7.62? I can’t imagine why they’re not trumpeting THAT from the ramparts....

Do we even know if it is .223 or 5.56 or Wylde?
I wouldn't be surprised if there is a blackout on reviews between now and SHOT, hope I'm wrong but as stated wouldn't be surprised.