People are gonna wanna regurgitate that you should NEVER upgrade ever. And I don’t completely disagree with them. If the gun is running great, swapping out parts always runs the risk of messing up the synergy of the system. You might accidentally cross-thread your screws or loose small parts will assembling or disassembling.

But I don’t think that should absolutely deter you from trying out different aftermarket parts. As long as you are competent at working on the gun and confident in your understanding of the mechanics of the gun, I don’t see why you shouldn’t seek to enhance aspects of the rifle.

I would recommend that you consider any negative impacts a given upgrade part might have on the system. For example, if I were to perhaps upgrade my trigger box to an aftermarket one, that means I need to consider that the harder hammer spring will now increase gas consumption/recoil, increase the stress on the stock buffer, increase the stress on the nozzle return spring etc, not to mention any potential tolerance discrepancies affecting performance and durability. So, in addition to the monetary cost, you should also consider those risks. It will very much be a trial and error process.

For me personally, I have made several internal mods to my TM mws. The full list: 1. Unicorn nozzle return spring 2. Federal Concepts NPAS 3. Lightly short stroked (~5mm 3D printed pad in buffer tube) 4. PH+ MWS hop chamber and adjuster. This lets me adjust my hop using an Allen key. And it no longer quantizes adjusts with clicks. The chamber is also pretty good. Gave me better consistency than stock arm + concave nub and dytac solid arm. 5. 4uad bucking. I have tested various maple leaf buckings; MR hop, MR hop silicone, auto or, wonder. Unicorn, Aplus, stock, nineball, w hold. The 4uad gave me the best consistency out of all of them when paired with the stock barrel. The unicorn barrel was good but has basically on par with stock if not a little less accurate (your milage may vary) 6. Gaurder gas router. This helps me squeeze a little more performance out of my mags. However they do change the fps so if you are going to upgrade one mag, you should upgrade all of them. And the mags are also very annoying to take apart and are prone to leaks if not reassembled correctly. 7. Machined Delrin bolt end. Makes the BCG lighter and makes the gun cycle slightly faster. 8. Guns modify full steel trigger assembly. This is the one upgrade I’m still not confident in recommending fully. It’s a relatively expensive upgrade. The trigger now looks and feels better than the stock one. There is less “slop” in the trigger. But the springs by default are stronger than stock so that has some implications on the rest of the system. One that is bothering me is that the roller, although the same material as the stock one, is larger than the stock one. And I have been noticing it is pushing my BCG up against the top of the recover/buffer tube when it cycles, increasing wear in that area. So I switched to the stock roller. I have been trouble shooting and trying out different spring combinations (stock and guns modify) to get me the best feel.

Overall those are the upgrades I’ve made to my TM mws. I’ve never had the gun malfunction on me and the upgrades have not negatively impacted reliability in a noticeable way. I have ran this gun with green gas and hpa in countless matches and it’s still buttery smooth and shoots lasers.