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M4 DMR project

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Hi I have recently bought a WE m4 cqb co2 GBB (closed bolt) rifle from this forum. it is a bit early as i have not recieved the gun yet but wanted to get this rifle made straightaway. I am hoping to upgrade and turn my rifle into a dmr type of gun. The following picture represents what im aiming for:




The only problem is, my rifle when i get it should look something like this:




As you can see i am missing very few parts! <_< this is my first gbbr and i understand this is quite a complicated weapon system and needs high maintenance. I'll talk about the main parts of this rifle that i need and/or need help with.



For this i was planning on buying a steel trigger set to strengthen the rifle. also an enhanced buffer and of coure an n.p.a.s kit. I wasnt quite sure about the bolt however. open bolt or closed bolt? to be or not to be? im not to sure how much difference it will make converting to open bolt. I am not sure about hop up though. i haave seen hop up and barrel sets but am not sure about the barrel length as i will explain in a minute. i have seen a double point hopup by FALCON but am not too sure about this. also the hop rubber.



As you can see in the pic above, i want a longer inner and outer barrel. I dont know about the length though as it needs to be the right length to fit with the handguard. I was thinking barrel length around 350 mm? also a tight bore inside i have seen 6.01mm and also 6.03. the first one sounds more accurate but i am not sure how much difference it will make. there is also the silencer to take into account also.



The handguard will preferably be railed but it needs to be long enough to fit the barrel as stated above (when i say 'fit' i mean follow the design of silencer in and out of the end of the handguard). It is not necessary but i want to put a spring eject bipod on the rifle and put rail covers on the rest of the handguard. I presume the front sight is removable but im not sure where the gas rod goes into if i do take i t off (if the rod is needed).



I am not to bothered about the stock but i am very fond of the magpul one in the picture. if i can't get one (i'm on a budget) then any sliding stock will do.



I have a 4x32 scope i need mounts for that i can use if not i would like a scope similar to 3-9x40. I considered an acog but for the length this rifles is going to be it will look out of place.



I have only seen the WE co2 m4 mags and don't know if any others are compatible. it also depends on whether i convert it to open bolt.


As you can see i am quite a noob on gas rifles (and airsoft generally) so i am hoping for a lot of support from the community. If anybody has suggestions, improvements, ideas answers to my questions, parts you have that i need, generally telling me how it all works and how my idea is goint of fail because i am an idiot :( . Please give me lots of feedback as i am not to sure on many aspects of the rifle, especially the internals! If all goes well i shall keep updating with pictures and comments on how it is going, thanks! :D


I have realised i say 'not sure' and 'don't know' a lot in this post!! :rolleyes:



Parts i need (i think):

  • Mags (not sure on no.)
  • NPAS
  • Enhanced buffer ( one ive seen adds 70% recoil)
  • Steel trigger set
  • Tight bore barrel
  • Hop-up and rubber (plus o rings and anything else)
  • Optics
  • stock
  • Handguard


If you can suggest any other kit i need and/or suggest the best product to buy for each of the above! Thanks


Suggested kit:

3 WE co2 mags (if not, gas)

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I used to have a closed bolt M16 and it was probably the worst performing gun I've ever bought, not because of gas consumption or anything like that, it worked fine, but the accuracy was worse than... I dunno, a toddler throwing a ball?


The closed bolt hop system is proprietary, you can't buy after market replacements from what I remember, the hop mechanism is the worst I've ever seen. I've heard mixed reviews about the open bolt system being better or not, but I'd advise going for it based on my experiences with the closed bolt. The open bolt gives you a new hop up design and it can't be as bad as the closed bolt hop, so there's got to be some degree of improvement.


Your M4 will be compatible with green gas and CO2 WE Tech magazines so long as they're of a STANAG style, so if they're labelled as being for an M4 or M16 variant, a HK416 or an L85 then they will fit and function. But make sure you buy the ones intended for the bolt set up you decide to go for as open bolt mags won't work in the closed bolt system and vice versa.

My M16 didn't run very well using CO2, it felt like the recoil spring wasn't strong enough to cope with it, but the M4's might be different because it'll be shorter. It might compress better or something, you'll have to see how it goes. You've mentioned looking at an enhanced buffer set? I would recommend getting one, I imagine they're to solve the CO2 bad cycling issues I had.


I can't really help regarding external parts because I only ever put an ACOG on my M16, I left the rest as it came but I think the WE M16 is compatible with real steel parts.


Also, I'll just correct you, as you've said you want a 350cm barrel lol, the rifle will likely be shorter than 70cm when it arrives. I'd say from the picture of how you want it to look you'd be looking at something like a 16 inch outer barrel set up? That's about 40cm or something like that?


You might be able to buy the entire front end that you're after as a drop in replacement if you look around hard enough. When I had my WE I spoke a lot to a shop in the US called Blowback Armoury, they're really helpful guys if you're needing advice on how to fit parts or dismantle the rifle to diagnose faults etc. Be aware that importing stuff from the US costs a bomb though, even if it's only something tiny.


The fake gas tube in the hand guard isn't needed, it's just there for realism, taking it out won't alter anything, thought it might cause the front sight to have a very small amount of left/right wobble.


As for internal upgrades regarding the trigger set and all that, look for RA-Tech parts, they're basically the company that WE should be, they make all their rifles good. If I buy another GBBR ever, it'll be an RA-Tech modded WE rifle.


Oh, one last thing, if you're going to replace anything, replace the charging handle. Buy a steel one and replace the hook that holds it forward for one that doesn't sit at such a high angle along the receiver. The hook on mine was the first thing to break, letting the charging handle slide forwards can smash the hook off by severing the metal through the pivot pin hole. After the hook breaks ('cos it will) make sure you secure the charging handle in the forward position with elastic or something, if you fire the gun when the charging handle isn't locked forward then it will slide back slightly on firing and when the bolt returns forwards it will snap the charging handle in half.

Basically, if you see any parts for sale that are steel replacements for the stock parts, then buy them. I think the gun is made from aluminium or a zinc/magnesium alloy or something and it's just not up to the job.


Good luck with your project, wish I had the cash to start an L85 GBBR project =[

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Thanks for the advice! yeah i didn't realise about the barrel length. i meant mm lol. RAtech internals was what i've been looking at and i have found a lot of steel replacements that should be quite handy. Their are buffers i have seen which impprove the cycling and improve recoil. Still not sure about mags though. will gas or co2 run through this without any adjusting? there are a lot of mags for rifles like the western arms m4's but i dont know whether they'll work as they don't mention open bolt or closed bolt like the we ones. the reason for picking other mags is because we mags are more exspensive and hold 30rnds whereas othere mags for e.g the WA m4's are cheaper and hold 40-50rnds.


L85 gbbr project would be a dream. if i had the cash i would have gone for that too.

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Western arms mags wont work, theyre for a different system- neither will G&P, pro win, ghk etc


Your best bet is to go with an open bolt version, its a newer system and more efficient and will perform better due to the new hop up design- similar to the tm vsr's


In the UK you best bet is to use co2 mags (check with you site if they allow co2 rifles first though) and run it with and NPAS to bring the fps down to a usable level.

Ra-Tech parts are great and worth the additional cost over normal, the super bolt recoil buffer will increase recoil a fair bit too which is nice.


As ed says, charging handles on gbb AR-15s always seem to break so a stronger one is going to be useful

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WE mags are a bit pricey, it's just the way life is unfortunately. As I say, any STANAG style mag made by WE will work, so long as you get the closed bolt mags for the closed bolt and the open bolt mags for the open bolt.

Other brands of magazine don't work, just the WE ones.

I think in most places the open bolt magazines are cheaper than the closed bolt ones as most people were itching to get their hands on the conversion kits. You don't see many closed bolt models around anymore, I don't think you can actually buy them new in the closed bolt set up.


I got my gas M16 as my first ever gun, so I learned the ins and outs of it pretty early on, since I got rid of it I find that I can comfortably last about an hour's worth of skirmish time with real capacity mags in my AEGs, so don't let the mag capacity put you off, it's the fact that you could also run out of gas in the mag, as well as ammo that starts to grate on you. You'll more than likely find yourself becoming very conservative with your ammo consumption. Firing a GBBR is an event because it doesn't happen very often, you can only shoot at what you can hit. You'll see what I mean once you take it out with you.


The gun ought to run fine on both green gas and CO2 without needing to change the set up, the NPAS kit you're thinking of ought to make the power output the same, or at least similar, so I can't see you having problems. You might find that the enhanced buffer will make it run better with CO2, so if you plan on using green gas or propane and you have cycling issues, just switch it back to the old buffer spring. Simples.


Oh I just remembered something else I had trouble with - Once you open the gun up you'll notice a screw that holds the buffer tube in place in stock to stop it shooting out when the gun is being taken apart. If you ever have the gun jam and get totally stuck so you can't even open it up then that screw is probably the culprit. With my rifle it kept slowly shaking itself loose until it obstructed the bolt mechanism, just make sure you screw it back down and maybe get some locktight on it when you strip it for maintenance.

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Thanks mate! I've found a steel charging handle to replace the stock one. and i guess then im going to have to spend the money on the we mags -_- how many do you think i will need? i'm not that trigger happy and seeing as it is a dmr i was thinking 3? (90 rnds = £105 on gas or £115 on co2) I will also have a sidearm so that brings up the firepower a bit. I'll make a list of everything i need in a bit so that people can give me recomendations or sell me parts they own. thanks


This is my first 'good' rifle for skirmishing as my previous kit wasnt so great. as you can see my armoury currently consists of half an m4 and a DE tri shot. but iam willing to put the money in and learn everything needed for this to be a top-notch rifle.

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I had 6 green gas mags and 2 CO2 mags but I very rarely used more than about 40 shots in an hour and since you're going to be using it as a ranged weapon, not a run and gun type, I'd say 3 is a good number to go for.

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I had 6 green gas mags and 2 CO2 mags but I very rarely used more than about 40 shots in an hour and since you're going to be using it as a ranged weapon, not a run and gun type, I'd say 3 is a good number to go for.

I'll go for 3 then i think!

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