ICS M4 firing issues
 

I'm experiencing issues with misfiring in an ICS M4. The gun was functioning perfectly until I recently installed a metal body.

This issue is confusing because most of the usual variables don't seem to apply. The first shot jams (I'm assuming in the hop-unit and the next shot bumps it out and it falls out of the barrel and subsequent shots do the same until the mag is removed and the final chambered round is shot out with normal fps. The mag is obviously feeding and there are no issues with air seal as the final shot consistently fires at normal fps. The tappet plate is fine, the hop-up rubber is in great shape and properly installed, I installed a modify nozzle and replaced it with the original ICS nozzle to make sure any compatibility issues weren't to blame (same issues with the stock nozzle). I'm wondering if ICS require propriatary sleeves? I've got a guarder clear installed, could that be causing the jamming? Has anyone experienced similar issues when installing a metal body or misfiring with ICS propriatary hop-ups?

which metal body did install(question mark dont work lol)

It's an older generation Olympic Arms body.

Double check for a crack in the hop-up body.

also, if your mechbox do not have a hole to install the cross-pin (if you have the black lower mechbox) it is needed when using the older metal bodies.

You can simply make the hole, but make sure you are certain where to make it.

Well that is news to me. I got the mechbox pin with the body and realized I couldn't make use of it (I do have the black lower mechbox). Thanks for the info, I'm guessing the issue is the mechbox is sitting too loosely in the body? Although the upper mechbox is extremely firm in the body and serves to hold the lower in place.

it's either a barel alignment problem or as stated the mechbox is floating.