Jump to content
Sign in to follow this  

Alex's P* Mk18 Build

Recommended Posts

Hi folks,


For starters I hope this is in the right place, I was stuck between here and the 'advice & technical help' sections... so apologies if I chose wrong! Feel free to move it to a more appropriate location if I've done a goof.


I'm going to start off with a quick TLDR of the whys and whats which led to the project starting and a picture of where it's at right now, following in to a parts list, future plans and finish up with all the weird little modifications that had to be made along the way.



So, I recently got back into the sport after a fairly lengthy hiatus and decided I wanted a project gun. I've always loved the 'bronze' DD rails so I landed on a Mk18 (as many do, seemingly).


I have an old CA M15 CQB lying around, so that was the intended donor RiF, the sizing didn't work out with the front end so it wound up being largely unused bar the stock tube and selector switch. Next up, was powering it. HPA is something that really piqued my interests, the versatility leaves it open to all the things i wanted out of the RiF. It was a toss up between the Fusion Engine and the F2, I landed on the Fusion Engine simply because I didn't trust that old CA gearbox.




Parts List

  • G&P M4A1 Receivers
  • G&P Receiver Fixings (Dust cover needed modification)
  • Madbull Daniel Defense RIS II 9.5" Dark Earth (Needed modification)
  • Madbull Daniel Defense 10.3" Government Profile Steel Outer Barrel
  • Magpul CTR Stock Dark Earth
  • PTS EPG Dark Earth (needed modification)
  • Classic Army Selector Switch (Wasn't a fan of the G&P one)
  • Classic Army Stock Tube



  • Polarstar Fusion Engine v2 Gen 3 (Stock poppet, blue nozzle)
  • S2 Lightning Banjo
  • Amped Airsoft IGL
  • Maxx Pro Hop Up
  • Maple Leaf Omega Nub
  • Prometheus Purple Hop Rubber (Needed modification)
  • Prometheus 6.03 280mm Inner Barrel
  • Maxx CNC Aluminum Advanced Trigger Gold/Dark Earth


Accessories - Current

  • Magpul RVG Dark Earth
  • Magpul RSA QD Sling Mount
  • Hurricane Eotech 551 Replica (Will be replaced at some point)
  • Acetech Lighter BT (Will be replaced with a KAC suppressor when it arrives)


Future Plans

  • Low Flow Poppet (If necessary)
  • KAC suppressor
  • PEQ15
  • M300
  • Dual Pressure Pad
  • Different Optic (Undecided whether to go for immitation accuracy or usability)
  • A paint job



So this section is for things I wasn't expecting to have to do, but did. I struggled to find information for a lot of these specific issues so figured I'd put my fixes here incase they can be useful to others, disclaimer that there are likely better ways of doing some of these... but they work sooooo *shrug*.


Madbull Rail Not Sitting Flush with Receiver

Pretty easy diagnosis on this one, the barrel nut was preventing the rail from sitting snug against the upper receiver. Decided to take some material off the front of the barrel nut using a dremel/files/sandpaper. I opted for the front because I didn't want to risk damaging the thread, though I imagine taking some material off the back would have reaped the same result. I did repaint the barrel nut black after material removal.




Dust Cover Not Closing

Thanks to a combination of the Fusion Engine and the big lug on the back of the G&P dust cover, the dust cover wouldn't close. I knew I'd need to remove the lug, but still wanted to the dust cover to close. I added a small square of metal (honestly no idea what it was) and a small magnet so the dust cover would attach to the faux bolt carrier plate. I need to whip this out and paint it at some point.




Receiver Gap

There was a gap between the upper and lower receiver. This was fixed using some foil tape to shim the back of the upper receiver.




IGL Line Noise

I'm not a big fan of leaving the IGL coming out of the pistol grip to just wobble around freely, the noise very quickly started to irritate me so I dremeled out the bottom of the base plate and added some sticky back foam to double as protection to the line from any poor sanding work on my part, and prevent it shaking around.




Feeds like a dream on PTS EPMs and chronoing in consistently on the 328fps on .2s I'm very happy with how it all came out. Unfortunately I won't be able to fine tune everything in until I can get out onto a field, I'll likely be running it on .28s when all is said and done.


Aaaaaaand that's a wrap... for now. If folks are interested I'll update the build once things from the 'future plans' list start to arrive.


Share this post

Link to post
Share on other sites

Just need this for the full sicario soldado look



Share this post

Link to post
Share on other sites

I can’t work out if I love or hate these stocks, and for that price I’d certainly have to land on love!




Share this post

Link to post
Share on other sites

Love or hate generally gets overruled by need

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Create New...