[Drake]

Originally Posted by movado

Thanks guy, I just bought WE M4 GBB because from my research it's the one that accepts the most real steel parts.

Any recommendations for upgrade parts and stores to buy from? I would like to buy from Canadian retailers.

I have several WEs, I'd say first and foremost the first thing you want to install if you want a gun that runs anywhere near reliably is an NPAS. Avoid the temptation of piecemeal upgrading to "steel parts" (nozzle, trigger, etc) unless you're going to do all the internals in one go, otherwise the steel parts wreck the non-steel ones in the same loop.

If you're looking to improve accuracy, you can swap out the inner barrel and hopup rubber for VSR ones (older productions actually came VSR/HiCapa spec barrels and rubbers; they'll work with the hop up unit). I've also heard good things about the Angry Gun hop up unit but have yet to try it.

Externally, RS parts I've used include buffer tubes (mil-spec) and castle nuts, stocks (use mil-spec buffer tube size), pistol grips, trigger guards, RS barrel nut fit so I'd say most RS screw-on front ends should fit, receiver plates (kinda recommend paying a few dollars more for a RS one if you plan on doing something like a single point sling setup), fire selector will fit but will give you semi only, charging handles will fit but the ones with a steel latch end up chewing up the receiver over time, forward assists fit (similar issue chewing up the teeth on the BCG but honestly its airsoft: if the BCG isn't returning to battery the solution isn't forcing it forward with the FA. Treat this as a cosmetic part). IIRC receiver pins fit. Pin detentes fit but the springs are different lengths (don't remember which way it went). AFAIK mag catches also fit. RS gas tubes fit but are purely cosmetic.

With some modifications, an RS upper can be made to fit (although the import of that probably isn't possible anymore because of the OIC).

Marui-compatible (G&P, GBtech/VFC, Madbull etc) front ends all fit fine.

In most instances I had to shim the barrel nut to get a tight fit and/or to get the top rails to space out properly (if you want a continuous rail between the receiver and the handguard). At the very least you have to use the o-ring that comes on the WE barrel; this is more of an issue if you build extra uppers from parts.

Also there's a spacer at the bottom of the buffer tube: don't try running the gun without it, it won't work (again, this is more of a building a 2nd upper issue).

You can also use M4 (carbine length) buffers. There are various aftermarket (airsoft) buffers and recoil springs, which combine to various effects as you'd expect. RS ones provide a few more options, specially the adjustable weight ones. Purely for tweaking. Never attempted it but guessing RS recoil spring is way too stiff to use.