Very Heavily Modified GBBR – KWA LM4c

If I recall correctly, there was a glut of AR-15 gas powered airsoft rifles released some time around 2008-9 which all held propane in their magazines and were quite a step forward by comparison to replicas which had been available previously on the airsoft market. I remember a lot of forum debates about the KJW, WE and WA system rifles and which one was best. Because they were very much all the rage at the time and delivered far greater realism vs an electric gun I took a lot of interest and started out with an AGM-branded chinese clone of a WA system M4. That gun would often misfeed and vent all the gas in a mag, along with over-hopping and sending BBs up in to the sky.

Fortunately I upload a lot of content and almost never delete anything so there’s still a clip of me shooting it from 2009 that is up on my YouTube channel:

After making many alterations and then eventually selling that gun, I sunk far too much money in to the WA based WOC rifle line from G&P, but I lacked the time or knowledge to maintain them and the magazines always leaked gas, which left the guns unusable. In 2013 I then moved on to the hot new gun at the time, which was the KWA LM4. It is almost entirely forgotten about as of 2025 in favour of the TM MWS and VFC offerings, but in the early 2010s the KWA was definitely the king, especially in the US. Most importantly the mags actually held gas and the ones I own still do so to this day, with no maintenance.

I started off with the standard 14.5″ LM4 and based the alterations to it on the rifle Travis Haley used in his Adaptive Carbine Pantaeo DVD (everyone was still thinking about the Magpul DVDs at the time). Then I wanted a shorter gun that would be as handy as possible for indoor games, which is particularly relevant since GBBRs aren’t very competitive outdoors compared to AEGs or HPA powered airsoft replicas. The LM4c model that KWA released with a 10.5″ barrel and some internal updates was the ideal base so I picked one up that looked as per the image below.

The small amount of machine work and Cerakote finish I had done to the 14.5″ gun had left me feeling ambitious with this next build. Too ambitious as it turned out, because I purchased the c model in 2015, but didn’t take the pictures contained within this post until 2020. I had decided on going as lightweight as possible and loosely borrowing from the aesthetic style of the HSP Jack carbine made by BCM which was also hot at the time; so a long build process began.

It took me a while to get all the parts together and get them all to fit, but the biggest hindrance was when I sent the gun off to have the cut outs made to the mag well along with a few other mechanical alterations. Sadly I can’t recall the name of the man I paid to do the work or the name his airsoft customisation business went by, but he went silent on me after a few months, which was well past the agreed timeline for doing the work. I found his number, tried calling him dozens of times, sent e-mails, facebook messages, carrier pigeons… no reply. I think at one point he claimed a parent was terminally ill, but I never found out whether that was true one way or the other.

I gave him many months to sort his life out and asked repeatedly to get my property back even without the agreed work being done, despite the fact I had already paid him for it. In the end I took a deep breath and physically went to his house – the only time in my life I had ever done such a thing and I never have again since. I knocked on his door and just asked to get my stuff back. He said it wasn’t at that address and that he ‘would send it’, so there was nothing else I could do at that point beside walk off his doorstep and hope. Eventually he came through, though in the end he had hold of the gun for pushing towards 2 years in total.

Once I had all the accessories and the actual base gun itself I sent it off for the grey Cerakote to be applied, but again sadly I can’t remember the name of the business I used. They had good reviews but I would certainly never use them again. Their turn around time was fine, but the inside of the upper receiver was as rough as an old road, with over-spray and clumped up pieces of Cerakote. Not ideal, seeing I had planned to polish the bolt carrier for the smoothest travel and maximum gas efficiency within the system. Fortunately my mate Jim who I’ve known for longer than I can remember and is a whizz in a machine shop was able to get the inside of the upper smoothed out, he also finished off the last few machining touches that enabled the whole gun to get put together as depicted.

I have added an M-LOK mounted light, SureFire pressure switch and Magpul sling, also slightly changed the rail covers and swapped to a BCM stock, since taking these photos, but the parts list for the version of the build shown here is below.

Working from front to back:

The vast majority of the internal parts remain stock, all I changed out in that regard was the trigger itself and of course the barrel part of the safety. With so much else being altered I was still feeling a little skeptical that the gun would function once I re-assembled it, but fortunately it actually runs very nicely.

A bit of a stressful process with the various hurdles that cropped up along the way, but an end result that I can quite confidently say is custom and unique. Oh and it fulfills its’ original design intent very well of course.