mimesis Posted October 13, 2012 Report Share Posted October 13, 2012 Just got in the PRS-2 stock, long handguard, and 18" barrel for Magpul Masada. The upper hole in the stock didn't align properly with the upper receiver; fortunately, a bit of work with a rat-tail file took care of that. My main problem is with the 18" barrel. It fits in OK, but the gun doesn't fire properly. The first one or two shots may be OK (or not), but after that it's as if the gearbox weren't cycling properly, or fully, and the bbs are projected 10 feet or so. The gearbox sounds weak and unhappy. A dull thonk at the end of one cycle. Swop back in the 14.5" barrel that the gun came with, and it immediately returns to normal, correct firing. Gearbox immediately sounds fine again. I've swopped back and forth a couple of times, with identical results each time. Battery is fully charged, btw, and as I say works perfectly with the 14.5" barrel. Also tried two different Magpul PTS magazines (long and short). Hop-up has been turned down to zero the whole time. I've compared the ends of the two barrels, and they look the same to the naked eye. Perhaps the bucking on the 18" is a fraction of a milimetre further out the back of the black metal housing, but essentially the same. How can a different barrel affect how the gearbox functions??? I figure it's got to have to do with the nozzle, perhaps not being allowed to travel all the way forward, but I don't see how/why this should be, if the 18" is supposed to be a drop-in alternative. It's not just the air-seal, because as I say the cycling of the gearbox sounds quite different (and not "right") when the longer barrel is in the gun. Any suggestions much appreciated. 18" barrel was too expensive to become a paperweight. Link to post Share on other sites
Sallinen Posted October 13, 2012 Report Share Posted October 13, 2012 Compare the length of the point that attaches the barrel to the gun between barrels gearbox end. Could the barrel be pushing the gearbox backwards resulting in twisted motor angle? I'm sorry but I am not familiar with the masada, but this popped up my mind so I thought it doesnt hurt anyone to spew it out Link to post Share on other sites
Jimmypie Posted October 13, 2012 Report Share Posted October 13, 2012 Or the weight of the new barrel putting strain on the lower? Again twisting or crushing something, it's free float right? The outer? Try supporting the barrel whilst firing , is there any movement or improvement in sound/cycle. Link to post Share on other sites
mimesis Posted October 14, 2012 Author Report Share Posted October 14, 2012 Thanks guys for the suggestions. I've tried a few things, but so far no joy. Perhaps this photo will help. The 14.5" is on the left, the 18" on right. The 14.5" is clearly more dark grey, whereas the 18" is black. There are three small visible differences, and one not visible. Starting from the top: 1. The bucking protrudes slightly more out of the 18". As far as I can see, this is because the back of the bucking, the part "above" where the inner barrel ends and "below" where the lips begin, is a good deal thicker. The bucking is made of such a soft material, and the difference is so small, that it's hard to believe that this is the problem. 2. The shoulder of the second, larger housing, is more angled (chamferred) on the 14.5" than the 18". Looking inside where this is supposed to fit, I don't see this as a problem. 3. The gas piston rod is a little bit longer on the 18". Note where it falls relative to the set-screw. I suppose this could be a problem if the hole it fits into is not deep enough, and I might try filing/cutting this down a bit. 4. The (not visible) spring behind the bucking housing that tensions the inner barrel and bucking, is distinctly stiffer on the 18" than the 14.5". In spite of all this, both seem to fit into the gun fine. Looking at the fit of one and then the other, I don't seem any real difference in terms of alignment. When the handle is tightened down, both barrels are rock steady. I'm inclining to believe that this is an air seal problem (bbs fired from the 18" at a range of 5 feet won't penetrate a single sheet of paper!). Link to post Share on other sites
frank.oldale@firstcu.ca Posted October 14, 2012 Report Share Posted October 14, 2012 Sounds funny but the hopup bucking looks to be sticking out more. I had to trim my bucking to shorten it as the nozzle was pushing on it and changing the entry to the barrel. This caused the BB's to either jam or shoot at about 20fps. Link to post Share on other sites
Gazw Posted October 16, 2012 Report Share Posted October 16, 2012 Have you tried swapping over the buckings to see if the one from your 14.5 corrects the issue? If not I would try that. My guess is it's an issue with the bucking. If that works order yourself in a selection to see which works best. Link to post Share on other sites
mimesis Posted October 16, 2012 Author Report Share Posted October 16, 2012 Thanks Frank and Gazw--you were entirely on the money! I swopped over: the spring, the washer, the black plastic clip, the bucking, and the metal housing with set-screw, from the 14.5" to the 18", and it immediately started working just fine. So the culprit is definitely the bucking (and perhaps the spring--18" one is a good deal longer and stiffer). Still surprised that less than one milimeter of soft rubber could make that much of a difference, but it definitely does. Will fit a Guarder clear or similar on 14.5" in due course. Link to post Share on other sites
Deadmeat Posted October 16, 2012 Report Share Posted October 16, 2012 Glad you got it sorted out... now tell us how good is the 18" barrel? Is it worth it? Are there noticeable benefits or is it just for the looks? Link to post Share on other sites
Gazw Posted October 17, 2012 Report Share Posted October 17, 2012 Hooray Rubbers are cheap so worth trying a few different types to see the results. Yes as Deadmeat says we are all dying to know how the 18 holds up against the other barrels! Strangely there seems to be a distinct lack of test results on the internets! Link to post Share on other sites
Gazw Posted October 17, 2012 Report Share Posted October 17, 2012 Don't know if people are already aware, but these guys specialise in custom work for the PTS Masada. https://www.facebook.com/AggressorStudio They are currently working on a Masada DMR project for a customer, and just told me for that they are "going to put a prototype reinforcement on the gear box, its gone reach 500fps or more" By 'prototype reinforcement' I believe they are planning to produce a whole new reinforced aftermarket shell Link to post Share on other sites
mimesis Posted October 17, 2012 Author Report Share Posted October 17, 2012 In limited testing, the 18" barrel now that it's working, is a laser beam. Very accurate, with repeat shots going in exactly the same place. Very pleased... though it should be a drop-in fit. Link to post Share on other sites
Deadmeat Posted October 17, 2012 Report Share Posted October 17, 2012 In limited testing, the 18" barrel now that it's working, is a laser beam. Very accurate, with repeat shots going in exactly the same place. Very pleased... though it should be a drop-in fit. I presume these limited tests are a noticeable improvement from your 14.5" barrel? I'm curious what kind of range are your tests? Link to post Share on other sites
Fragkiskos Samolis Posted October 20, 2012 Report Share Posted October 20, 2012 my experience with masada sais that if you put the weight of the weapon on the barrel this affects the hop up. so maybe your barrel pushes the nozzle upwards and this affects your gears. Try pushing the barrle upwards while you shot and let me know. Link to post Share on other sites
Fragkiskos Samolis Posted October 20, 2012 Report Share Posted October 20, 2012 Hmm after replying i noticed you already solved it! Nice to hear! Link to post Share on other sites
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