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Initial Impressions of the TM PX4 GBB Pistol


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I just got a PX4 and it is a lovely gun but I keep having feed issues.

The follower in the magazine seems to get jammed every few rounds causing me to dry cycle.

Is this a known issue and if so has anyone come up with a fix for it yet.

I bought three magazines with the gun and have this issue in all three.

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after read this thread I'm going to buy TM PX4...its seem fun and don't mine add another pistol collection

It's helpful to mention what temperature you are using green gas (propane); I imagine it's fairly cool in the UK and I understand gas pistols work well with propane there.   With propane (or any pro

To take out the trigger...hell I was going to explain it, just follow this video : )     If there is anything you're not sure about, do ask.

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Yes, I've seen this reported before.

 

Just to get this out of the way: I assume you are filling mag with the bottommost bb down on where the follower is at an angle, and that there are no voids in the rest of the bb stack.

 

Some people have reported just changing bb brand did the trick.

 

Others have lubricated inners of the bb slide, follower, lips, etc. with the tiniest drop of silicon, and also reported that this helped.

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The follower in the magazine seems to get jammed every few rounds causing me to dry cycle.

Use quality BBs that run freely against each other. Matte BBs are generally a bad idea: They can cause the above problem, leave dirt inside the gun and fly worse ;)

 

I'd recommend G&G BBs.

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Here's a thing. Recently installed a tbb and new hop rubber, everything went back together seemingly fine. Afterwards the fps had almost halved, first bb fired but gave the impression it was under protest, the rest would nonchalantly trundle or roll out of the barrel.

Stripped it down again, hop platform not putting any hop on at all but seems to be functioning correctly. Re fitted original parts again, still doing the same? What have I done to it?

Fitted new barrel / hop rubber to a G-17 and all as it should be? Any ideas ?

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Here's a thing. Recently installed a tbb and new hop rubber, everything went back together seemingly fine. Afterwards the fps had almost halved, first bb fired but gave the impression it was under protest, the rest would nonchalantly trundle or roll out of the barrel.

Stripped it down again, hop platform not putting any hop on at all but seems to be functioning correctly. Re fitted original parts again, still doing the same? What have I done to it?

Fitted new barrel / hop rubber to a G-17 and all as it should be? Any ideas ?

 

Brand of tightbore/BB's you're using? Also, brand of hop rubber? I had slight fitment issues with the Nineball rubber in my PX4 back when I had it..

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Now that is odd. I found with the Nineball rubber, it was just half a mm or so too long to seat correctly in the hop unit; Trimming it solved that, but it doesn't sound like your issue.

 

Is the leaf spring that applies hop definitely seated correctly? It took me a few attempts to get that back in the right place, and that could well be causing the issue if it's not correctly installed.

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See I found there were 2 places it'd happily 'sit', one of which being incorrect obviously - Any chance of a decent picture of how you're seating it? Chances are it could be something else causing the problem, but it'd help rule it out. I figure it's engaging with the adjustment wheel and moving up and down correctly?

 

I'm assuming the BBU is all functioning as it should - Pulls itself back into the correct position and everything? All clean and lubed I'm guessing is an obvious one... Definitely sounds like a hop unit issue though.

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Im having a little trouble with mine recently, well more with the metal slide that was released for it some time back.

 

The gas effiency is crazy bad 1 mag and its out. Also it seems to be spitting a little gas out of the ejection port, after every shot which would acount for the gas effiency problem.

 

The piston head appears to be in good shape no damage, the nozzle seems fine too.

 

Anyone know why?

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I thought that could have been the reason and spent an age with it. All seems well and as it should be?

With the inner barrel and hop-up unit out of the gun, look down the barrel from the opposite end to where the hop-up is, and gradually turn the hop-up adjustment wheel. What do you see? Go, gradually, from minimum to maximum.

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I haven't seen a PX4 hop-up, but if it's anything like other TMs, there's a tiny L-shaped piece of metal that fits into a groove on the adjustment wheel, and on the other end sits on top of the bucking and is supposed to exert downward pressure when the wheel is turned.

 

I feel that the L-shaped piece may have got bent out of shape. Try bending the two "arms" of the L in towards each other--slightly!--so that they form a slightly more acute angle. The top part of the L should therefore press down on the bucking more, making the mound on the inside of the bucking be more visible as you adjust up the hop.

 

BBs dribbling out the barrel is a sure sign of insufficient hop. It's the bucking and the internal mound in the bucking that holds the BB there awaiting the next jet of gas.

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Not very much really. When checking with no hop rubber the platform rises. With it assembled no matter which hop rubber the platform seems to rise but make no impression on the hop. Bb's roll out of the barrel when re assembled.

 

It sounds like the little tab on the hop leaf spring might not be engaging with the hop wheel itself - When re-assembled, there's a line cut into the adjustment wheel, that this 'tab' slots into, thereby moving the leaf spring up and down when the wheel is moved.

 

Still, if it's moving without the hop rubber, that sounds like it's adjusting correctly... See if any other PX4 owners have any pictures of the hop unit handy, as it really does sound like something isn't installed right. And unless the L shaped spring is really quite significantly bent, it shouldn't be performing that badly if that's the cause of the issue.

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Nice to see this pistol doing so well. Not too many complaints or issues being posted. It's a solid "piece" and continue with a fair following. Everyone who shoots mine seems to be impressed. It really is made quite well. In the top 3 of my Marui collection.

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I thought I'd update with another upgrade part on the market :D

 

http://www.uncompany.com/pageproductdetails.asp?prodid=32400

 

I dunno if the SD gaskets for the Glocks did any good for the Glock crowd but if they did I guess those willing to spend cash to milk every bit of performance from the gun can consider getting those for their mags :D

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