Classic M4 Build Off—Leo’s Edition

Alright y’all! After some harmless confusion, I have figured it out. Everything related to my build will be posted here.


I’ll be competing against @danerd but I’ll be taking my build in a completely different direction.

My base gun is a TM M4A1 carbine length AEG (not the NGRS), chosen to provide a bit of a different, more classic flavor compared to what I usually run, as well as having a few desirable attributes for the build.

For now, my concept is of an “apocalypse” AR, built using a combination of old parts and new.

Everything will be “weathered”, and most likely painted (patterns and colors TBD).

I’ll be keeping the carrying handle, as I think it looks kinda sick.

I’ve decided to keep the original stock to help ground the build, although I’ll probably be adding a stock pouch.

I’ll be changing the grip, mostly likely to an EMG/Strike slim grip, but that’s yet to be determined for sure.

For the optic, I’m caught between form and function: function would have me do either an open reflex sight, or none at all, but I have a 1-9x hunting scope that would look great, and really fit the theme.

I’m still debating the muzzle device I want to use. For regular use, I have a very nice looking RS Surefire Warcomp .556, or a foam filled “mock” suppressor can that may be used to hide an extended barrel, but I also have an RS Silencerco suppressor for a real M4A1. It can’t stay on the build permanently, but it can stay for a couple of pics.

I’m looking at adding a sling, but not sure yet—I have a buddy who somehow acquires just about every piece of tactical gear known to man, so I’ll see if he’s got anything.

For the hand guard I’m still doing my research—the Magpul MOE SL is my top contender, but I’m also admiring the BCM PMCR. Nothing determined yet—research to be done!

I’m looking at adding a Krytac Trident sling plate, but first I have to see about sourcing a sling.


That about wraps it up for my ideas on the externals, now we get to the insides:


Danerd is probably going to outdo me on the externals, build aesthetics, and cool factor (GBBR), so my chance to pull ahead is on the inside. I’ll be using a GATE Pulsar, with the aim to achieve an effective range of 90 meters using heavy ammunition. I’ll be trying to keep the FPS under 450 w/ .20g, but if necessary I’ll go up to 500.

Since very few people have this engine so far, the limits aren’t well known, so I might have to adjust my effective range goal as I begin tuning and tinkering.

For now, I’m trying to use the supplies I have on hand, and unfortunately I only have a couple inner barrels in the 380 range, which is where I’d ideally want it.

I have two Lambda SMART barrels, 6.08mm and 6.03mm, but both are 509mm. The HPA engine should be able to correctly volume either, but it may cut down on efficiency and potentially even accuracy.

Unless I source a different barrel, the most promising choice is looking to be a T.N.T. S+ 387mm.

I’m going to take a look at the stock hop unit, but since I prefer to work on rotary units, I’ll likely use a G&G polymer rotary (assuming it fits).

I’ll be testing several packings and nub combos to determine what works the best with the engine and with the gun itself, but I’m leaning towards a ML MR.Hop silicone 85* and either a 3D printed RHop arm or a homemade concave nub (I would probably cut out of plastic; broken barrel clips work great, since they’re already the right ID.)

Everything will be exhaustively tested, fitted, and stabilized to attempt and provide peak accuracy.

Unfortunately, Danerd’s build looks to be no slouch either, so I have my work cut out for me.

The second requirement of the internals, is that I’m going for complete silence. Though accuracy comes first, I will certainly adjust barrel length and other factors to attempt and make this rifle as quiet as possible. (Here’s where the foam-filled suppressor comes in)


And that about wraps it up for my build ideas/notes so far.


And one final note; Since I didn’t want to allocate my budget to buy a $200 Yong Heng air compressor, I opted for a hand pump to fill my air tank. Put your bets in, ladies and gentlemen; how many times do I fill the tank before I give in and buy a real compressor??