Can you do me a favor tell me how much the reciprocating mass weighs?
- Thread starter newguy2k3v2
- Start date
Give me an hour or so
Thank you
Sorry, got stuck at work late
1lb 8.8oz
1lb 8.8oz
No problem. Thank you very much!
So what's the project you need the info for ?
Trying to make my POS mdr work. It seems like it has a similar gas port location to the scar but the reciprocating mass is only 13oz. Despite assurances from DT that it was fixed each of the THREE times I've returned it to them it still doesn't run. Short strokes and stuck cases.
If you haven't already I'd send DT pictures/video of the gun short stroking and sticking cases. Had a similar problem with an M1A and had to send it back twice. Finally the third time I sent photos and a short video. Finally came back fixed.
See here's the issue with that. The 6pos I have now is actually the 3rd different valve they've put out. The suppressed port at least on the original 3 position was too large and ripped case rims. The 2nd 3 position worked most of the time. The current 6position was supposed to allow fine tuning yet here I have a gun that more often than not short strokes in the 1st position and eventually rips rims in the 2nd.
The new 2019 6position looks to have larger ports across the board again.
Short stroke= not enough gas
Ripped rim= too much gas/extraction too early.
The gun is the most picky eater I have ever seen and it's not even worthy or range toy status unless malfunction drills are your jam. All the ammo this one can't handle is flawless in every other semi it's been fed through.
Ideally I'd like to see a longer gas system to delay extraction and reduce port pressure but that would be a much larger undertaking. Increasing the reciprocating mass to bring it closer to norms will be a much easier and cheaper experiment.
Sure, but if you tune too wide you get folks bitching that the gun is over gassed. See all the SCAR re-jetting conversations, and DD MK18 overgassing issues that have been discussed.
You also need to consider from a product design perspective, user education. Or better stated the complete lack thereof in the vast majority of cases.
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The way the mdr is set up it has a narrow operating range. Enough gas to reliably cycle the action and ejection system is on the edge of ripping case rims off and it eventually does when it gets dirty enough. It unlocks too early. It's easily the dirtiest operating firearm I've ever seen. Go a click down on the gas adjustment and it doesn't have enough bolt inertia to operate properly.
I'm aware of the issues with the MDR. I saw their response video, and I hope the new valve works better for folks.
I guess the points I was trying to make:
1. Ammo is highly variable in quality.
2. A gun company typically gets blamed when their firearm doesn't cycle horrendously out of spec ammo.
2a. Gun companies proactively "overgas" to quell the whining of people shooting under spec steel cased ammo in $3000 rifles
2b. Because of 2a, people who shoot in spec ammo, or shoot suppressed complain about guns being over gassed
3. Gun owners will bitch about anything
4. Giving consumers more ways to adjust the gas system doesn't == nirvana. Usually quite the opposite. Typical consumers have no idea what they are doing, or why. They are monkeys with hammers working on watches.
Yes these are all broad brush statements. I stand by that on average, they are accurate.
All mostly valid but the mdr absolutely needs adjustment to fire different types of ammo. Take any typical ar-10 with the same ammo and it just works. The design is flawed.
In complete agreement.
