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Replacing a CYMA CM 506 M4 ⬆&⬇ receiver with a BOYi HK 416 M4 ⬆&⬇ receiver?

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I've been working on my M4A1 (CYMA CM506) for a while now. It's my first real airsoft gun. The only thing I can't get my head around is the following;


I want to simply replace my CM506 body, upper and lower receivers, with metal versions. I've found a BOYi HK416 upper and lower M4 parts that come with the usual small pieces. My CYMA is a Version 2 geatbox so that's fine but my only concern is if the outer and inner barrels will fit. I have the barrel guard already metal, same for stock tube. Ive made no internal alterations so it should simply be factory standard things. Nothing fancy.


Can I swap the plastic CYMA receivers for the BOYi ones?


I hope you might know.


Kind regards,



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Most likely not. Boyi's metal body is probably the worst available and their QA is so bad that many times Boyi parts don't even fit other Boyi parts. And different brands have different dimensions.


The cyma is a good gun for its price but it's just not worth trying to upgrade it. Same reason: airsoft parts only look similar but are always slightly different. A certain brand makes a gun then the parts in it are mostly compatible with themselves, but trying to replace anything with an other brand will most likely not work properly.

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Damn. That's depressing as all hell. 

Plus side, you were able to let me know decent and useable info. Thank you SO much for that. I don't have the funds to make a mistake like I almost did. The parts from my CYMA M4 would only have been the V2 gearbox. The rest of the items aren't CYMA but standard M4 ones. There were two different companies that have the upper and lower. BOYi was one. The other is D-BOYS who make an M4 AEG upper and lower. What immediately caught my eye was the male names, BOYi and D-BOYS being almost the same name. The other is that on the D-BOYS one that state;


Finished in Matt black and fully Tokyo Marui M4 AEG Compatable this receiver will fit the majority of brands including G&P, CYMA, JG, Classic Army etc.


I don't suppose that you'd know/heard if they're true to their word or are just a secret North Korean plan to target what little I have?




Either way, I'm grateful that you've been able to pass on the important warning about fits and BOYi being a no go as a company.


Tabi, or Tom if my phone's spellchecker kicks in again ^_^





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Boyi and dboys are the same. Their guns are branded boyi and the parts are dboys or something like that. But they are the same company.


If I were you, I would play with the cyma and leave it as it is while saving for a somewhat higher spec gun. Then look for one second hand or a Specna Arms or A&K M4.

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Great. Thankyou for letting me know.


It's a shame that CYMA don't make a metal upper and lower but hey, they've made a good M4 so that's good.


Thanks again for the clarification on the two names being the same company.



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