Definite manufacturing issue with 2k9 mag

[OPBN]

No issues here. Love my MM2K9.

[zondo]

What length on/off pins is everyone using?

Did anyone have to adjust the clevis length?

[zondo]

(Dont look too closely at the deten't positions either)

I am going to be pissed at myself if this is the case...

[nak81783]

Could anyone with a MM2K9 body please do the following:

1. State whether you can or cannot achieve 300fps in the MM2K9 setup using a valve that is verified to work in another setup.

2. Measure the following:
A to B. From center of rear field strip screw hole to bolt spring seat (without washer).
A to C. From center of rear field strip screw hole to aft edge of breech piece.
A to D. From center of rear field strip screw hole to aft edge of feed tube.

MM2K9 Schematic.JPG

3. Place two balls in the feed tube (positioned vertically) without a hopper. Shoot the bottom one, and report what the top ball does (flies out of feed tube, feeds properly, jostles a bit, etc.). Try to quantify if possible. For example, it flew 2 feet out of the feed tube.

4. With a ball chambered, does the centerline of the ball line up with the centerline of the bolt and the centerline of the barrel?

Hypothesis 1: Bolt geometry is too far back relative to breech. Bolt releases power pulse too far back, losing much of the pressure up the feed tube.

Hypothesis 2: Air blast isn't centered on ball. It is concentrated above or below it.

The previous posts simply measure compression of the spring, which can be remedied by using a shorter or longer spring, using a thicker steel shim, or boring out some of the material at the bottom of the hole (depending on if your measured distance is shorter or longer than AGD spec).

Your data is greatly appreciated. Thank you.

Edit: Here's a link to the other relevant thread. Takes a while for us to figure out it's the body.

http://www.automags.org/forums/showthread.php?265053-Unusual-RT-Pro-Issue

-Nathan

[Henchman]

Will do. Need to pick a proper caliper this week.

[Henchman]

Well, the issue is exactly what I suspected all along. I even told the people at PTP when I sent my 2k9 back to them,mand they said the measurements were correct.
They had it over a year. I just got it back. They said it was fixed, and that it was an issue with some o-rings etc.

Not.

When I tried to get it over 170bps bps, it started leaking air again.
I order a caliper.

Well, the measurement is a whole half centimeter or a liittle over 3/16 of an inch short of what it should be.
From the center of the retaining screw to the edge of the breach, it measures 7 1/2 cm. vs 8 cm for a proper working Tac one.
So, the spring is already extremely compressed and too much force is needed to compress the bolt when firing the gun.

[sniper42]

So the feedhole is too far back? See at least on mine, the hole for the valve is actually bored deeper than a standard mag, even with the steel insert installed. What is the depth from your quick strip screw to the front of the steel insert?

[Henchman]

That's the measurement I'm talking about.
The breach wasnt drilled out deep enough.
The screw holes in the right place.

[sniper42]

Interesting. My body is drilled .150" longer than a standard mag yet has similar problems. Yours should be a somewhat easy fix though. You would just need to have the hole bored a little bit deeper, assuming all other dimensions are ok.

[Frizzle Fry]

I'm seeing similar variances with my Minimag, ULE and Xmag bodies.

I'll check more markers but they seem to have as much .185" variance in either direction with these stock AGD bodies.

[nak81783]

So, the spring is already extremely compressed and too much force is needed to compress the bolt when firing the gun.

Respectfully, if this were the only issue, and it may be the issue on your particular body, you could simply cut down a spring to get it working. Frizzle Fry's response bolsters this, and could simply be the reason we all have slightly different Level 10 spring setups. Apparently, this is not a dimension AGD felt the need to hold a tight tolerance on. From our ability to adjust dump chamber pressure to the selection of springs we have, as well as the ability to trim springs to suit, I would agree this dimension is not critical.

However, there are certainly other issues with other bodies, as sniper42's also does not work, and the measurement you are talking about is longer on his body, not shorter.

I feel the only way to get to the bottom of this is to get the data I requested from working and non-working (for whatever reason) bodies alike. If you feel there is another measurement that can contribute, by all means, add it to the list.

I am certainly not the know-all, end-all, but I do feel it's time to let the data drive us. Let's get all the hypotheses out there, and collect whatever data may be necessary from as many members as are willing to contribute to prove or disprove each and every hypothesis.

Relevant thread: http://www.automags.org/forums/showt...l-RT-Pro-Issue

[OPBN]

[sniper42]

I'm planning on whipping up a print in solidworks once I have some time to sit down and sketch it.

[OPBN]

I'm planning on whipping up a print in solidworks once I have some time to sit down and sketch it.

Ok. Mine was going to be pretty primitive. One thing I would like to do is figuring out how to compare bodies visually. I had thought about putting the bodies on a grid backgroud to show where things fall.

[nak81783]

Henchman: Please reply to this post: http://www.automags.org/forums/showt...73#post2836273