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m102404 · January 7th, 2009, 19:09

Thank you Manchovie! I don't have the benefit of working on multi-generations of airsoft...I'm more centered on what's here and now, but it's great to get the background information.

Thanks to Vic_man4's background on KWA as well.

While we were asked for our problems or suggestions and I don't necessarily feel the need to justify my comments...I'll gladly fill in a bit more detail if it'll help in any way for a manufacturer to put out continually better products.

I am of the opinion that TM used a split design to facilitate the break open design of their plastic M4's. How well the upper and lower hopup seal at that critical junction is dependant on how consistently and tightly the upper and lower closes. Wear, abuse and variations in QC would all adversly affect the seal. Does it do the job? Yes. Would it be better to remove that potential issue/area of compromise...yes, I think so. It's not a 100% certainty...but the number of broken hopup uppers (from closing it improperly) tells a tale of a design issue (at least with "users" breaking them).

With a one piece hopup design, you have a "non-leaking" pathway from the bb inflow to the nozzle to the hopup rubber lips. Do some hopups tend to work better than others? Absolutely. I have several "spares" (actually a box filled with them) that just don't seem to work in any build. There's a CA, G&P, Guarder, Deepfire, and a half dozen Dboys (I kept a few...but then just started to throw them out in the garbage). Does not mean that those brands are junk...just means that I've not been able to get those individual ones to work right.

The KWA M4 shell is metal...nicely casted/finished. They "copied" TM's plastic body right down to the last details (re. the hopup section). It is exactly like the TM M4 body...except in metal. I would have much prefered to have seen a 1-piece hopup design used...solely for the fact that when it came time to replace/repair/"upgrade" it is infinitely easier to take a one-piece hopup unit and swap it in (providing you pick a good one).

The other "issue" that I have with their hopup unit/nozzle is that the nozzle is indexed with a ridge that fits a slot in the upper hopup. It works just fine and to date, at least with the 10 or so KWA M4's that I've worked on, the factory nozzle has fit/sealed relatively well with the cylinder head. Most are very good...2 were loose (IMHO). Nozzles wear. Nozzles break. I'd rather be able to replace that nozzle with something commonly/readily available vs. being either stuck to using a single type or else replacing the entire hopup system with a 2 piece TM replacement (which are not always readily available). When I speak of readily available, I mean that in the sense that I'd like to start and finish a repair within 2 evenings...and not have to stock parts I might not need or shelve repairs while I wait for parts to be shipped in.

Perhaps the "advantage" of other designs is that their replacements are readily available and different variations are available from different manufacturers.

Re. metal piston heads...again, it's my opinion that the "softer" the shock to the front of the mechbox (especially v2's) the better off the mechbox shell is. Whether the shock is spread out over a longer time or whether it's reduced in amplitude...I don't discern. No comment on ported vs. non-ported...that wasn't my point. There is no give in an aluminum piston head...but at least it is hitting a thin rubber pad on the cylinder head. Is that sufficient? Maybe...and if KWA did the research and put automotive class engineering into it...well that's why they did it. But would a different material be perhaps more forgiving and hedge your bets on extending the life span of the mechbox? In my opinion, yes.

Final word from me.
I've recommended the KWA M4 variants (well not the S-system version...I think the handguard is cheesy) to several people and they've been happy with them. 2 have had their metal piston heads come loose and blow their cylinders and pistons.

I do think that they are very well built and one of the best stock M4's out there. Can it be made better?...yes. My next personal M4 build will based on a KWA M4A1...it's sitting on my bench right now.

January 7th, 2009, 19:09	#7
m102404 Tys Trader rating Join Date: Apr 2006 Location: Toronto	Thank you Manchovie! I don't have the benefit of working on multi-generations of airsoft...I'm more centered on what's here and now, but it's great to get the background information. Thanks to Vic_man4's background on KWA as well. While we were asked for our problems or suggestions and I don't necessarily feel the need to justify my comments...I'll gladly fill in a bit more detail if it'll help in any way for a manufacturer to put out continually better products. I am of the opinion that TM used a split design to facilitate the break open design of their plastic M4's. How well the upper and lower hopup seal at that critical junction is dependant on how consistently and tightly the upper and lower closes. Wear, abuse and variations in QC would all adversly affect the seal. Does it do the job? Yes. Would it be better to remove that potential issue/area of compromise...yes, I think so. It's not a 100% certainty...but the number of broken hopup uppers (from closing it improperly) tells a tale of a design issue (at least with "users" breaking them). With a one piece hopup design, you have a "non-leaking" pathway from the bb inflow to the nozzle to the hopup rubber lips. Do some hopups tend to work better than others? Absolutely. I have several "spares" (actually a box filled with them) that just don't seem to work in any build. There's a CA, G&P, Guarder, Deepfire, and a half dozen Dboys (I kept a few...but then just started to throw them out in the garbage). Does not mean that those brands are junk...just means that I've not been able to get those individual ones to work right. The KWA M4 shell is metal...nicely casted/finished. They "copied" TM's plastic body right down to the last details (re. the hopup section). It is exactly like the TM M4 body...except in metal. I would have much prefered to have seen a 1-piece hopup design used...solely for the fact that when it came time to replace/repair/"upgrade" it is infinitely easier to take a one-piece hopup unit and swap it in (providing you pick a good one). The other "issue" that I have with their hopup unit/nozzle is that the nozzle is indexed with a ridge that fits a slot in the upper hopup. It works just fine and to date, at least with the 10 or so KWA M4's that I've worked on, the factory nozzle has fit/sealed relatively well with the cylinder head. Most are very good...2 were loose (IMHO). Nozzles wear. Nozzles break. I'd rather be able to replace that nozzle with something commonly/readily available vs. being either stuck to using a single type or else replacing the entire hopup system with a 2 piece TM replacement (which are not always readily available). When I speak of readily available, I mean that in the sense that I'd like to start and finish a repair within 2 evenings...and not have to stock parts I might not need or shelve repairs while I wait for parts to be shipped in. Perhaps the "advantage" of other designs is that their replacements are readily available and different variations are available from different manufacturers. Re. metal piston heads...again, it's my opinion that the "softer" the shock to the front of the mechbox (especially v2's) the better off the mechbox shell is. Whether the shock is spread out over a longer time or whether it's reduced in amplitude...I don't discern. No comment on ported vs. non-ported...that wasn't my point. There is no give in an aluminum piston head...but at least it is hitting a thin rubber pad on the cylinder head. Is that sufficient? Maybe...and if KWA did the research and put automotive class engineering into it...well that's why they did it. But would a different material be perhaps more forgiving and hedge your bets on extending the life span of the mechbox? In my opinion, yes. Final word from me. I've recommended the KWA M4 variants (well not the S-system version...I think the handguard is cheesy) to several people and they've been happy with them. 2 have had their metal piston heads come loose and blow their cylinders and pistons. I do think that they are very well built and one of the best stock M4's out there. Can it be made better?...yes. My next personal M4 build will based on a KWA M4A1...it's sitting on my bench right now.