Unusual RT Pro Issue. . .Now confirmed as micromag 2k9 problem!

[sniper42]

I will try spacing the detents out and see if that helps. I haven't done the dykem yet but I will try that too. I will disassemble it and take it to work. We have full sets of precision guage blocks so can figure out internal dimensions of everything.

If I were to make a new shorter on-off pin to try, which side is shorter, the fat side or the skinnier side?

[nak81783]

For the $8 or whatever they cost, I would order one. That way you get the right tolerances, material, etc. You could get another .750 on order, and start grinding down the one you have, unless you need your valve working for something else before the new part would arrive.

Anyway, I believe you would want to grind down the smaller diameter. However, I've never done it, so you might want to seek some consenting opinions first. I will measure my .750 and .712 pins tonight and let you know where the length variance is.


-Nathan

[nak81783]

I just realized I never measured these for you. Length difference is definitely in the smaller diameter, as I expected.

X-Mag pin: .712" overall length with .162" length of head diameter

X-Valve pin: .752 overall length with .160" length of head diameter

How's this going? Any updates on the MM2K9 body?


-Nathan

[sniper42]

Thanks I appreciate those. I tried backing the detents out until they were barely engaged and there was no change. I haven't done much other than that though.

[nak81783]

One other idea came to mind. With the .150" longer distance from rear field strip screw hole to bolt spring seat surface, we have focused on the compression of the spring, but what if the bolt is releasing air .150" too soon relative to where the ball, breech, barrel, etc. are? Pressure will take the path of least resistance, so if the bolt stem clears the powertube oring before it's far enough forward, I bet you are losing a lot of the pressure intended to fire the ball out of, most likely, the feed tube.

Bear with me, my solution is a small science project, and I haven't taken any measurements to confirm it will all fit. Make a .150" shim to go inside the powertube. Drop this in first. Then, put in the Teflon backing washer. You will probably have to grind/file down the face of the carrier to get the powertube tip to thread on. If you make the bushing with the OD and ID of the Teflon washer, you could leave the Teflon washer out, saving you that amount of thickness you'd otherwise have to grind off the face of the carrier. I'd try the carrier without grinding first, but I doubt it will allow the powertube tip to thread on all the way without grinding.

Whew, yeah. There are other ways of achieving this (e.g. longer bolt stem), but I think the aforementioned is easiest, especially since you already made the one bushing. You should be able to make this bushing on the same equipment. Heck, perhaps you could stack up small washers to achieve the .150", whatever is going to make that bolt release the air .150" further in its stroke forward.

Does this all make sense? It may be easier to do it with a Level 7 setup first. Less parts to stack up, but you could apply the same logic. Also, I must warn that changing where the Level 10 vents may eliminate its anti-chop capabilities. If you go the Level 10 route, I would use large carriers that you would probably otherwise never use. Don't worry about a barrel leak, just see if it works.

Edit: Scratch the Level 7 idea. I forgot about the pesky bolt stick issue if the oring is too far forward in the powertube.

-Nathan

[OPBN]

While I have never had an issue with my MM2K9 body, I do know that at one point they were offering free steel inserts to put inside the valve side of the body to prevent damage as some people were reporting mushrooming.

[nak81783]

While I have never had an issue with my MM2K9 body, I do know that at one point they were offering free steel inserts to put inside the valve side of the body to prevent damage as some people were reporting mushrooming.

OPBN: Sniper42 stated in an earlier post that the low velocities and .150" longer distance occur with the steel insert installed. Without the steel insert, he can get to 290 with a trimmed spring but is worried about damaging the aluminum body. How thick is the steel insert? I suppose Sniper42 could put in a much thinner steel insert to get close to the 290 mark, but he would have to keep an eye on it. The thinner material may wear out quicker.

Sniper42: Forget my previous post. I took a bunch of measurements, mixing and matching Level 7 and Level 10 parts. The small stem length of the Level 10 is not long enough to move the seal point up .150". I also tried sealing on the larger stem diameter. Although I got it to fire perfectly fine, there is no way to move the seal forward on the larger diameter without custom machined parts. Sorry.

Also, see my comments to OPBN about the thickness of the steel insert. Did your marker max out at 290, or did you just stop there, even though it could go higher?

Finally, I guess the easiest way to test my .150" air vent hypothesis is to see how far back the bolt face is from a paintball when that paintball is resting against the detent(s). Compare that distance to your other marker, which will be really hard to do with a side/powerfeed and twistlock. That said, I measured mine (ULE body) at 1/8" to 3/16". If your MM2K9 body is more than that, this hypothesis might hold some water.


-Nathan

[OPBN]

The insert is hard to measure, ITT it's about .065 or less thick. It's not flat. I did miss where he had the insert. I've tried measuring my body before and can't seem to ever get an accurate measurement to see if only some bodies were off or what. It puzzles me why only some bodies can't seem to reach the correct FPS while others have zero issues. Odd.

[athomas]

What are the measured size of the paintballs at the seams? What is the inside diameter of your barrel? What is the length of your barrel? What is the length of the barrel before the porting starts?

[sniper42]

OPBN: Sniper42 stated in an earlier post that the low velocities and .150" longer distance occur with the steel insert installed. Without the steel insert, he can get to 290 with a trimmed spring but is worried about damaging the aluminum body. How thick is the steel insert? I suppose Sniper42 could put in a much thinner steel insert to get close to the 290 mark, but he would have to keep an eye on it. The thinner material may wear out quicker.

Sniper42: Forget my previous post. I took a bunch of measurements, mixing and matching Level 7 and Level 10 parts. The small stem length of the Level 10 is not long enough to move the seal point up .150". I also tried sealing on the larger stem diameter. Although I got it to fire perfectly fine, there is no way to move the seal forward on the larger diameter without custom machined parts. Sorry.

Also, see my comments to OPBN about the thickness of the steel insert. Did your marker max out at 290, or did you just stop there, even though it could go higher?

Finally, I guess the easiest way to test my .150" air vent hypothesis is to see how far back the bolt face is from a paintball when that paintball is resting against the detent(s). Compare that distance to your other marker, which will be really hard to do with a side/powerfeed and twistlock. That said, I measured mine (ULE body) at 1/8" to 3/16". If your MM2K9 body is more than that, this hypothesis might hold some water.


-Nathan

My velocity maxed out at 290 but it felt like the gun was kicking hard. Harder than my classic valved mag does at the same velocities.

My bolt sits about .150" recessed back from the feed hole. With a paintball all the way forward against the detents, it looks like it is another .150"(roughly) forward so it seems like it is about .300" from the bolt face. One thing to note, I am getting quite a bit of blowback up the feedstack. If I am testing without a hopper and load two balls so one is in the breach and the next is sitting on top, when I fire, it shoots the chambered ball, but there is so much blowback in the feedstack it shoots the second ball up a few feet.

And to athomas, I am shooting valken redemption pro, about .689 at the seams through a .689 freak insert in a 12inch DW fibur barrel.

[nak81783]

Crap. That's exactly what I was afraid of. Excellent reply, by the way. I think we are on the right path. FYI, I can place three balls in my ULE or X-Mag, and the top one just jostles a bit, so I think this hypothesis is starting to hold some water. OK, here we go...

OPBN: Does the bolt face sit recessed in your body as Sniper42 describes?

OPBN and Sniper42: Please measure, if you can, the distance from the face of the body material on the aft inside edge of the breech slot (actual breech piece removed) to the aft surface of the steel insert. My guess is Sniper42's will be ~.150" longer than OPBN's. If so, here are the options, as I see them. If you feel it's worth it, you will most likely only be able to do one or the other, so it'd be wise to get input from others with this body (and same problem) to chime in. Asking Tunaman, BigEvil, tymcneer, and luke is also probably a good idea or anyone else with machining experience that has seen these bodies.

1. Machine .150" (or the difference between your and OPBN's measurement) from the surface against which the steel inserts sits. This is part A of method 1. You may get lucky, and this solves it. It will allow the bolt to move further forward in the marker, hopefully reducing the blowback, and more importantly, the lost air pressure up the feed tube that I think is causing your low velocities. This is dependent on the bolt stem being long enough in its current condition to be properly guided by the powertube and reset correctly as well. This does not cure when the bolt releases its charge, which is why I said the aforementioned was part A. If this does not solve the issue, part B of this method is moving all the locating holes/slots forward that same distance. I'm assuming JB Weld, Alumiweld, or something similar may work for a test, but it would need to be something harder for a long term fix. Anyway, the front and rear frame screw holes, sear axle hole, and slot in which the sear moves must be moved forward the appropriate distance. The new features will most likely overlap with the old (or be extremely thin-walled), which is why I mentioned the JB Weld, etc. Also, you'll probably need to move the hole for the vertical ASA or make some type of adapter, as moving the grip frame forward will interfere with the foregrip (unless the foregrip could be slotted out to accept the grip frame). Whew, yeah, the pro of this method is you might get lucky with Part A. The con is Part B seems like a lot of work, and is questionable with the overlapping holes, weld material, etc. However, option 2 may be difficult as well.

2. Machine .150" (or difference measured between OPBN's body and yours) from the aft surface of the breech slot on the main body. Mimic all existing geometry (e.g. counterbores, slots, etc.). Install a custom shim forward of the breech (in the gap that will now be there), and figure out a way to attach it. Pros are this method seems a little easier overall (surfaces are more exposed for machining, not changing as many locating features), no weld material, etc. The con is there is no quick-and-dirty-hope-I-get-lucky-on-Part-A. If you don't want the shimmed look, you could make a new front piece that accepts the barrel, and move all geometry backwards, counterboring the front .150" simply to accept barrel body diameters.

Finally, I doubt it will matter, but as for the varying distance from rear screw hole to bolt spring seat, you can use the shim you previously made to get the various springs to act the same as a marker with the "proper" distance.

If you feel any of this is worth it, please keep in mind I do not have one of these in front of me, and I have never handled one. I am strictly going off pictures from the web and the data you provide. That is why I suggest you get others with experience with these bodies (and preferably, machining experience) involved. I feel my hypothesis is valid, but all measurements and decisions should be made by a competent individual that can measure all these things with the body in hand.

It's early, so if any of this needs clarification or doesn't make sense to a well-rested population, please ask.

Good luck.

Edit: Option 3: Custom bolt with nose .150" (or whatever the lacking distance is determined to be) longer than standard bolt relative to other important geometry (base of bolt, Level 10 vent hole, latch surface, etc.). This one wouldn't show cosmetically. But again, it will require machining.


-Nathan

[athomas]

The barrel shouldn't be a problem then.

If you shoot when the ball is back against the bolt, is the velocity any higher that when it is forward away from the bolt?

Even with a shorter more compressed spring area, using the shortest bolt spring will allow you to operate with less opposition. The thing that I can see having an effect is that the large part of the bolt stem may not be clearing the powertube tip far enough to allow adequate air flow. If you have another powertube tip around, try cutting off the front in tiny increments and see if it makes a difference.

[nak81783]

athomas: The compression area, and therefore stroke length, is longer on this seemingly defective body. This would mean the bolt is releasing the air too soon relative to the breech/barrel geometry, correct?

I realize all the machining I recommended is extreme, so by all means, keep the simpler ideas coming. I truly hope I'm wrong.


-Nathan

[OPBN]

Gawd Nathan, how much freaking coffee did you drink this morning? I walk into the office barely awake and see your novel above. You're giving me a headache too early today. lol. Let me get some caffeine in my system and I'll do my best to get some good measurements later today. Just have to find my skinny tape measure and motivation.

[athomas]

athomas: The compression area, and therefore stroke length, is longer on this seemingly defective body. This would mean the bolt is releasing the air too soon relative to the breech/barrel geometry, correct?

My thought process wasn't firing on all cylinders for some reason. I read past that part and was thinking that because the bolt was seated farther back, the whole bolt movement was farther back for some reason. That just wouldn't make sense. Thanks for correcting that.

The theory of releasing air too soon is much more viable.

Measure the distance to the start of the barrel. Then lay out the bolt with respect to the valve and you should get a good idea of when the large bolt stem clears the powertube tip. This is when the power impulse behind the ball is produced. If it happens too far before the bolt tip is in the barrel, it could definitely impact the amount of velocity you are getting.