TM HiCapa - Some BB rolling out the barrel

[MultipleParadox]

So a friend of mine handed me his TM HiCapa 4.3, stock, for me to give it a look.

Despite the fact I know my way pretty well around that platform, I am no expert gundoc with years of exp. so I figured I could go fishing in that knowledge pool that is ASC :P

Here's the details:

Problem:
Most shots are fine, but once every 10-18 shots, 1 BB will roll down the barrel when it's being chambered. more rarely, two consecutive shots will do the same. and then it will be fine for the rest of the mag.


Tests I did so far:
I tested with both his mags and mine. Same issues, we can rule out the mags.
I also put his slide on my 4.3 frame, the same seems to happen (although MAYBE less frequently, but I haven't tested enough to really be sure about this yet). I have a Tanio Koba grip and guarder mag catch that's quite snug on mine.

Since I got the same problem with his slide, I would rule out the mag/mag catch as a source of issues for now.

Slide cycling is fine and great.

Hopup was set to approx 50% with .30g BBBastards

I just did a complete disassembly/reassembly (appart from the hammer mech);

Nozzle looks like it's in great shape.
Return spring was a bit short, I stretched it a wee bit so the nozzle doesn't move freely when at rest.
The piston head/nozzle interface feels a bit weak to me, but I am not ready to say it's a problem yet.

That's about the amount of info I could gather in a couple of hours, will take a deeper look later on.
In the meantime, if anyone has some kind of ideas or suggestions of test to do, let me know!

-- Invoking ILLusion and is magical brain! -- :P

Thanks guys

[jordan7831]

A guy just posted a really insightful video on TM hi capa trouble shooting. Perhaps try some of these.

TM Hi-Capa Hop-Up Trouble Shoot (HD) - YouTube

Summary.
1. Check the barrel for cleanliness
2. Check the hop up rubber for air leak
3. Check the hop up adjustment arm

Hope this helps.

[Rusty Lugnuts]

almost certainly a hop issue- try more

[Sequential]

Hop up issue, adjust the hop up more. If that doesn't work then bend the little metal so it is on more of a curve so it pushes the rubber down a tiny bit more.

[Styrak]

Turn up the hopup. I use about 75-80% hopup in my Hicapa when I'm using 0.25's.
0.30's are pretty heavy and would need more grip to hold them in I would think.

[GBBR]

check the hop up sleeve to see if it has been torn. the nub would still effect it and hold it but without the sleeve BBs can roll out

[MultipleParadox]

I had a feeling the issue would be around the hopup; thanks for (almost) confirming this

I'll check it out later

[ILLusion]

This is a fairly common issue with the Marui Hi-Capa 4.3 (specifically the 4.3, and not so much on the 5.1), especially when using propane. It's more likely to happen, if you're using any aftermarket shock buffers and/or an enhanced recoil spring as well.

Because of the light mass of the OEM slide, it cycles extremely quick. Combined with the original hop up rubber not being as sticky as some aftermarket options, when the slide returns to battery, it chambers the next round in so fast and hard, that it can have a tendency to pop the round past the retaining seal in the hop up rubber.

The cheapest solution is to try soaking the hop up rubber in dish soap to suck out any excess silicone oil in it... BUT, this problem will happen again once you start firing oiled gas through the gun again. The best and easiest solution is to just upgrade to a better hop up rubber. Other options, could be to upgrade to a metal slide to slow down the movement speed/momentum energy.

[MultipleParadox]

That totally makes sense
I'll try my rubber in there and see if it fixes it
Thanks for the explanation!

Originally Posted by ILLusion

This is a fairly common issue with the Marui Hi-Capa 4.3 (specifically the 4.3, and not so much on the 5.1), especially when using propane. It's more likely to happen, if you're using any aftermarket shock buffers and/or an enhanced recoil spring as well.

Because of the light mass of the OEM slide, it cycles extremely quick. Combined with the original hop up rubber not being as sticky as some aftermarket options, when the slide returns to battery, it chambers the next round in so fast and hard, that it can have a tendency to pop the round past the retaining seal in the hop up rubber.

The cheapest solution is to try soaking the hop up rubber in dish soap to suck out any excess silicone oil in it... BUT, this problem will happen again once you start firing oiled gas through the gun again. The best and easiest solution is to just upgrade to a better hop up rubber. Other options, could be to upgrade to a metal slide to slow down the movement speed/momentum energy.

[Sequential]

Originally Posted by ILLusion

This is a fairly common issue with the Marui Hi-Capa 4.3 (specifically the 4.3, and not so much on the 5.1), especially when using propane. It's more likely to happen, if you're using any aftermarket shock buffers and/or an enhanced recoil spring as well.

Because of the light mass of the OEM slide, it cycles extremely quick. Combined with the original hop up rubber not being as sticky as some aftermarket options, when the slide returns to battery, it chambers the next round in so fast and hard, that it can have a tendency to pop the round past the retaining seal in the hop up rubber.

The cheapest solution is to try soaking the hop up rubber in dish soap to suck out any excess silicone oil in it... BUT, this problem will happen again once you start firing oiled gas through the gun again. The best and easiest solution is to just upgrade to a better hop up rubber. Other options, could be to upgrade to a metal slide to slow down the movement speed/momentum energy.

+1 on this one. I had the same issue on my 4.3 after an upgraded Aluminium slide. I tried to soak my original hop-up rubber with dish washing soap, and alcohol to get it all out. But whenever you use green gas or propane the issue comes up again.

Changed the original hop-up into the nineball one but the nineball one still had the same issues of the bb rolling out.

The final solution to fix this was to bend the hop up adjustment arm. :salute:

[ILLusion]

The caution with bending the arm, would be if you bent it too much, it would put a slant on the nub, causing the BB to fly to one side.

If this is the final solution, then I offer two different products that do something similar (bringing the nub down further.) The ILLusion Kinetics Steel hop up adjustment arm (resists bending more than the original material), and the A+ Strike Chamber (which is just an add-on plate.) I don't recommend combining both parts together, unless you are shooting ultra heavy ammunition (0.30g+).

[MultipleParadox]

Illusion:

Yes that's the very reason I don't want to bend that arm; A fix that reduce accuracy is not a fix I'd say :P

Do you have a link of that Strike Chamber? What's the price like?
It might be a good solution; I was thinking of putting a shim or something between the arm and the nub too; I guess that could work well, assuming I can make sure the shim doesn't move

[Sequential]

Bending the arm worked for me

My gun shoots very accurate now after with the nineball hop up...

[MultipleParadox]

Originally Posted by Sequential

Bending the arm worked for me

My gun shoots very accurate now after with the nineball hop up...

Well I'm sure it *can* be a viable option to some extent, but because of how the arm is made, you can't really bend it downward without it being "crooked" and unlevel. So you augment the risk of it causing your BB deviate because of the uneven pressure applied to it

[Sequential]

Originally Posted by MultipleParadox

Well I'm sure it *can* be a viable option to some extent, but because of how the arm is made, you can't really bend it downward without it being "crooked" and unlevel. So you augment the risk of it causing your BB deviate because of the uneven pressure applied to it

It was the only way I could fix the bb rolling out issue, if I didn't bend the arm the bb would just keep on rolling out.

Of course you can always buy a new arm that is better, but I didn't want to put too much money into a 4.3 since it is already shorter and less accurate than it's big brother 5.1.