I bought a Viper Tech 2015 edition M4A1 RAS GBBR in August of last year.

Never. Fucking. Again.

It was basically 'fresh from the factory' but when it came, it was completely messed up. Here is a list of all the things that were wrong with it:

The magazine well had excessive scarring on the inside of it, and it would also not take GHK magazines at all, which the previous year generations could - this was the main reason for me buying it in the first place.

Anyway, the inside of the magazine well was scraped up to shit.

The rear locking pin holes were not machined properly and the pin needed the thumb of god to go in properly.

The front post was not timed correctly.

The buffer tube delta ring had damage/crimping from being over-torqued.

The ejection port cover spring-pin crimped the ejection port area, basically weakening the strength of the closed ejection port (it kept opening easily).

The charging handle was chewing up the upper receiver charging handle latching area very badly. The gun seemed to have disintegrated or eroded itself just by being there. Viper Tech use 6061 Aluminium, instead of the expected 7075 Aluminium that the older models were made of; 6061 aluminium is better for chemical resistance, but is far weaker than 7075 grade. I did not know this new model was 6061 grade, and they said it was 7075 grade. Upon sending it to a material tester, he confirmed it was indeed 6061 grade.

Since the receivers were 6061 grade aluminium, and the charging handle latch was steel, the gun would essentially smash itself the fuck up whenever you would rack the charging handle to use it.

It is still for sale and I am looking for £450 for it... :(

I can send images upon request.