TM 5.1 Hi-Capa - cannot engage safety
 

Hi everyone,

Just wondering if there's someone in Richmond/Vancouver who can take a look at my Hi-Capa. I've put maybe 200 or so bb's through it and now I can't engage the safety.

The slide no longer seats properly and I can't figure out why.

I know this is what it's supposed to look like:

But I can only get the slide to line up properly when the locking pin (not sure what it's called?) is removed. Then if I look through the hole, this is what it looks like:

The only way to clear the hole is to shift the slide back a bit, but then it's not in the right position and the safety won't engage.

Take off the slide, and move up your safety lever, and if it goes up, place it down, and place the slide back. After that, try it again, if not, fire a couple of shots, and try the safety again.

I've taken off the slide and looked around for any obstructions, didn't find anything. Can anyone tell by these pictures if something is not seated right, or not how it should be?

Quite a peculiar problem after 200 rounds

1. Check the blowback unit to see if it got loose, check the screw at the back under the rear sight to see if it is secured tightly

2. Check to see if your loading nozzle is fine and no cracks or out of place

3. Check the outer barrel to see if there is any shifting

What was the very last thing you remember doing as its quite strange after 200 rounds to have that problem

Also try taking apart the internals in the slide and inspect the parts

Ohhh hmmm can you take more pics of your blowback unit something does not seem right either its me but from the pics it looks like something is stuck

everything is stock on this I presume? there might be interference between the lug/chamber area between the slide and outer barrel.

does that look like the O-ring backed out?

Took the slide off again, the safety lever goes up and down no problem, fired off a few more shots, BBs come out, no problem, but I did notice that bbs spin upwards.....that didn't happen before.

It's your hop up your turned on.

Is your safety working now?

Is that an oring at the back of your blowback unit? Cause if so that's definitely not right. Does it even fire correctly?

The piston in the blowback unit should sit flush with the back of the slide.

I've never adjusted the hop-up, got the gun brand new and it's completely stock. I tried dialing the hop up back completely (all the way to the left), put everything back together and the slide still isn't seating properly.

Yep, I think you're right. I've slid the o-ring back down the blow-back unit. Is it in the right place now, or is it supposed to be further down into the lower groove?

Yup that was the problem. You'll want to put it in the groove at the end. You'll want to lube it so that doesn't happen, it was probably completely dry or something. Or you have to get a smaller/tighter oring.

Should work fine now.

Personally I've never had this happen to me before, but I've heard its a common issue....

but then I never had mine BBU interface stock for long...

Cool, thanks! Here's a pic of where the o-ring should be, and I hope this thread can help anyone else who may run into this problem.

The green gas I used when I first got the gun was self-lubing, but then lately I started using propane and it probably got a bit dry. Is it ok to use this silicone lube on the gun?

You have an old Hi-Capa with the older piston head design. These were prone to having o-ring blow outs like you are experiencing. Newer TM Hi-Capas have a piston "cup" design which eliminates the problem. It was switched when the 4.3 hit the market.

Switch to an aftermarket piston head setup to eliminate the chance of it happening again. Once it happens, it will happen more and more frequently until you swap the part out.

I have some cheaper ones ($8) that use a high quality German o-ring in stock if you don't want to spring for a fancy schmancy one. Can ship anywhere in Canada for $10 via lettermail.

I'm still new to airsoft. I'll read up a bit about piston heads in the upgrade section and see what I should do. Fancy or plain....not sure yet.

Basically, the "fancy" ones are ventilated and made of metal. Other than that, they can't get much more fancy. The cheap ones I'm selling are made of some synthetic material - I'm guessing nylon/Delrin. The o-rings used are stronger than the Japanese ones, so they're not as likely to blow out of the groove.

I'm a sucker for fancy. But it seems I need to change a bunch of other stuff before I can reap the benefits of just changing to a ventilated metal piston head right?

wrong. You can just go directly with the head alone.