I dunno I may be biased some but I call BS. So the dude filled it to EXACTLY 1450 right before... Sure. Nobody ever says they fill their gun to 1450 unless they want YOU to know "dang" sure they didn't 'overfill' it. All we know is that this happened in the summer in some guy's vehicle while it was banging around in one of those thin fabric cases. You see that damage and you've all seen what 1500 psi is capable of. Could that have been caused by 1500 psi? It's certainly possible but I don't think its probable. I'm willing to accept all the hate and discontent that this will generate but please understand that there is more going on here just based on the descriptions.
I imagine quite a few GTA members know what they fill to for best performance and it isn't 3k psi in a 3k psi gun in quite a few cases.
I have been extremely careful to try and present only the facts that have been given to me, and to try and analyze those logically to the best of my ability.... If indeed the threads did pull apart, it would have been about the least likely mode of failure that could be expected.... I only have a sample of one to base my opinions on (my son's FD-PCP), and although the threads are a bit loose, I have every confidence this would not happen to it.... However, there are reports of much looser samples circulating, even in the XS-60c which the FD-PCP is based on.... That may be part of the story, I hope we eventually get to the bottom of it....Calculations of thread strength are based on the assumption of a proper overlap and fit between the male and female parts.... This insures a shear plane of very nearly 50% of the material threaded together.... The shear plane is the pitch diameter (roughly the mid-point between inner and outer diameters) times PI, times the length of thread engagement, divided by two, because half the area in shear is in each part, male and female.... The weaker material in shear should fail first, in this case the aluminum receiver instead of the steel tube.... It the threads are not fully engaged, because the female threads are cut too deep (too large an ID), or the thread on the tube too deep (too small an OD), or both, then only the tops of the triangular threads are touching instead of the full face of the thread.... Think of a pyramid, with an inverted pyramid pressing to the side of it.... Now slide the inverted pyramid up, and draw a line through the mid point of the overlap.... The area providing the strength is reduced.... Since the strength of the material is the area in shear times the shear strength of the material, it is now weaker.... Eventually, the weaker material will fail.... Explaining this failure (and assuming the threads pulling out is what we are dealing with, still undetermined but it seems likely) is difficult.... It is possible that the tube was only threaded in a thread or two, although you would expect to see the last thread in the receiver missing in that case.... However, considering that the seal between the tube and the receiver is located 3/4" inside the receiver, where the end of the tube compresses a square-section O-ring against a shoulder, it would be very difficult to get it to seal at all if the tube were only threaded in a turn or two.... The air should have literally poured out nearly as fast as you put it in.... I would point out that even a few threads, properly engaged, should be plently for strength.... even with a soft aluminum receiver.... Finding the missing tube would certainly help a lot....Bob
Who takes a gun they have never used, loads it into the car, along with the wife, and drives to a neighbors house to shoot the gun just 3 times (unless something happened to it)? And then fill the gun, to 1450psi (which I'm sure would have taken just a blip of air, right? Would 3 shots have even taken the pressure down 100psi), and drive back home? Not me. I mean why just 3 shots?
The goal as I understand it was to gather a rough idea of what it shoots in order to sell it. I would not need more than 2 shots to do that...cheers,Douglas
IMO some are getting pretty close here to calling other GTA members liars....
And if you take the time to really read this entire thread, you would discover that this is not hearsay. The event actually took place at the home of this thread OP's home. All they were interested in is shooting this airgun to see if it shot in the advertised power range before offering it up for sale. And they needed to make certain since they had never shot it in the two years of it being a closet queen.Yes, they could have spent a hour or so doing a string or two as well as checking accuracy. But I understand he just wanted to move out an airgun he had no use for. Enough said about that, so let's please stick to the facts and getting to the bottom of this failure.
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