kizza Posted February 8, 2009 Report Share Posted February 8, 2009 Hi there, I recently purchased the ACM (chinese copy of the Marushin) M500 shotgun (shorty). The gun was great but the green gas capacity was poor. I wanted to use this weapon as primary and keep firing rounds through it with consistancy and power. So, I read up on google and found only one person who had attemped this before (filipinofreak of airsoftforums.com), I asked him a bunch of questions and he answered them with no problems. Now I own possibly the best airsoft shotgun (one of) on earth, no joke. Also, this mod is a bit expensive with items. Bearing in mind I ordered most items from the states the total bill came to around £160 Below i'm going to show you a step by step procedure, with pictures, on how you can do this modification yourself but please note, I HAVE NO RESPONSIBILITY IF YOU DAMAGE or RENDER YOU GUN USELESS! You need the correct tools and machines for doing this mod, I will list them all below. So, here it goes. 1. First off your going to need the ACM M500, full stock or shortie it doesn't matter, they both have the same gas mechanism inside. Items you're also going to need: A ACM M500 B Q size drill bit (search for this on ebay) C 1/8th NPT -27 tap (for creating the thread, search for this on ebay) D UPZ remote hose (or other, search for this on ebay) E Female Stabilizer – select option 0 -200PSI (from Palmers Pursuit shop http://www.palmer-pursuit.com/cart/index.p...products_id=175here) F PTFE tape (search for this on ebay) G 9oZ, 16oZ or 20oZ Co2 bottle (bought mine from ebay, you could buy elsewhere) Tools your going to need: - Pillar drill (I used a regular hand drill BUT I would not recommend this if your not experienced) - Tapping tool (This sort of thing) - Metal cutting Saw - 6mm allen key - Flat head screwdriver - Phillips screwdriver - Hammer (or something to use to tap a bar out) - Filer - Vice Thats about it! Once you have everything above continue below. 2. Next we're going to disassemble the M500 to take the gas reservoir out of the gun. To do this, for the shorty version, take your 6mm allen key and undo the rear bolt just above the pistol grip. This will reveal the trigger mechanism. Next, undo the trigger mechanism by using a Phillips screwdriver and undoing the screw in front of the trigger. You will also have to use a hammer & something long/thin to tap the bar out holding the mechanism in on the side of the gun. Gently pull the whole mechanism out. We're now left with the gas reservoir To take the gas reservoir out, pull the pump/cocking handle towards you but do not push it back up. Tilt the gun upwards and the whole thing should come out along with some metal bars. Your done! Remember to place all the parts you removed somewhere safe! 3. Place the reservoir in a vice. Making sure no gas is in the chamber, unscrew the refill valve all the way out, then take your metal cutting saw and saw off the nub where the refill valve went to reveal a flat surface against the reservoir, file off any burs. We're now going to drill a hole where the original refill valve went, where we just cut the nub off. Place the reservoir under a pillar drill and clamp it tight! Use a drill bit smaller than the Q size to make a guide for yourself. SLOWLY come down with the drill making sure you use LOTS of oil (I used 3 in 1) in the process to prevent damage. When you're ready, place the Q size drill bit into the pillar drill and repeat the process above. REMEMBER TO BE EXTREMELY CAREFULL WHILST DRILLING!! Now you've drilled we're ready for tapping. 4. Take your 1/8 NPT -27 tapping piece and place it in the T-bar tapping tool. Next, again place the gas reservoir into a vice and clamp tight! Remembering to use lots of oil, slowly guide yourself into the hole whilst tapping. REMEMBER, rotate once then take half a turn back every time, this is to get rid of the metal debris and to prevent the thread we're creating from becoming damaged. Keep repeating above (1 turn, half turn back) steps until you've created the thread (about 10mm deep) Next, rotate all the way round to bring the tapping piece out. We've now created the thread. PHEW! That's the hard part over. 5. When you receive your UPZ remote paintball hose remove the following parts: We actually only need the hose and a few fittings. So, unscrew the regulator and opposite side black paintball fitting until you have this: Your left with: Left: Single 1/8 NPT fitting Right: Female Quick disconnect + Male Valve 1/8 NPT With this, attach the left side to the Stabilizer; remember to use PTFE tape on the thread to create a seal Use the correct sized spanner to tighten the fitting into the stabilizer On the right hand side, screw the male 1/8NPT valve into the threaded hole we created in the gas reservoir, remember to use the PTFE tape again on the thread. Use the correct sized spanner to tighten the valve. You can now attach the quick disconnect fitting to the male valve on the gas reservoir. 6. We're now basically done, all you have to do now is reassemble the gun (use step 2 in reverse) You will also have to connect your Co2 bottle to the stabilizer by simply screwing it in. NOTE: With the stabilizer you can adjust pressure output All you have to do is use an Allen key Congratulations, you now own one of the best & unique airsoft shotguns ever. Remember to frequently disconnect the quick disconnect valve and spray silicone oil into the reservoir to keep the O-rings lubricated Most importantly have fun and play safe. I will feel privileged to answer and questions Cheers, Kieran, aka Kizza Link to post Share on other sites
Bloodsword Posted February 9, 2009 Report Share Posted February 9, 2009 Nice socks! Link to post Share on other sites
kizza Posted February 9, 2009 Author Report Share Posted February 9, 2009 Cheers Link to post Share on other sites
MadDog Posted February 9, 2009 Report Share Posted February 9, 2009 Nice one, I've done the same kinda thing to my Maruzen M870, running on HPA at 250psi, shoots 8bb's at 260fps. What kinda pressure are you running your setup on? Link to post Share on other sites
kizza Posted February 9, 2009 Author Report Share Posted February 9, 2009 Nice one, I've done the same kinda thing to my Maruzen M870, running on HPA at 250psi, shoots 8bb's at 260fps. What kinda pressure are you running your setup on? s At the moment, running at about 200 PSI, 5bbs, 330 - 350 fps .25g How did you get it to fire 8bbs? Link to post Share on other sites
shmook Posted February 9, 2009 Report Share Posted February 9, 2009 How did you get it to fire 8bbs? its a maruzen shell ejector im guessing, 1 - 10 bbs/shell Link to post Share on other sites
kizza Posted February 9, 2009 Author Report Share Posted February 9, 2009 its a maruzen shell ejector im guessing, 1 - 10 bbs/shell Just read on it, nice gun. You have to fill each individual cartridge right? Link to post Share on other sites
shmook Posted February 9, 2009 Report Share Posted February 9, 2009 only with bb's. the gas lives in an internal tank in the gun (rear stock or pistol grip, depending on the model). with tanaka shotguns, the gas lives in the shells along with the bb's. although i hear these are a lot more finicky to use, both guns, and shells. Link to post Share on other sites
TheMerchantOfVenice Posted February 10, 2009 Report Share Posted February 10, 2009 That is awesome. I might consider doing it if it's not ungodly expensive. If you don't mind me asking, how much did the Co2 setup cost you? Also, how skirmishable is it, and where do you hide the hose and Co2? Link to post Share on other sites
shmook Posted February 10, 2009 Report Share Posted February 10, 2009 That is awesome. I might consider doing it if it's not ungodly expensive. If you don't mind me asking, how much did the Co2 setup cost you? Also, this mod is a bit expensive with items. Bearing in mind I ordered most items from the states the total bill came to around £160 Link to post Share on other sites
TheMerchantOfVenice Posted February 12, 2009 Report Share Posted February 12, 2009 Wow, I feel stupid. Link to post Share on other sites
kizza Posted February 16, 2009 Author Report Share Posted February 16, 2009 Just recieved my 0-700 PSI pin for the Stabilizer (original was 0-300) and my oh my, I had some fun in the garden literally blowing away random items. Obviously I will tone down pressure for skirmishes Link to post Share on other sites
shmook Posted February 17, 2009 Report Share Posted February 17, 2009 Wow, I feel stupid. we all do it kizza, this is ace! it makes me want to do the same to mine! Link to post Share on other sites
kizza Posted February 17, 2009 Author Report Share Posted February 17, 2009 we all do it kizza, this is ace! it makes me want to do the same to mine! I played with it on Sunday (2nd Skirmish with the gun) and it performed wonderfully. I actually can't point out any negative things besides the stock charging arms (they snap easily), I had to get a new pair. I get a lot of questions asked when playing and the distinct 'ker klunk, pow' turns a few heads Link to post Share on other sites
shmook Posted February 17, 2009 Report Share Posted February 17, 2009 it still has the distinctive 'pop' when fired then? Link to post Share on other sites
kizza Posted February 17, 2009 Author Report Share Posted February 17, 2009 Nope, with CO2 there is more of a 'Doosh' sound even set at 200 PSI (350fps) Link to post Share on other sites
shmook Posted February 17, 2009 Report Share Posted February 17, 2009 cooool! Link to post Share on other sites
airsofter0866 Posted February 17, 2009 Report Share Posted February 17, 2009 I have my maruzen m870 hooked up to co2 at the moment. Any chance for a video of the m500 shooting with co2? Link to post Share on other sites
kizza Posted February 17, 2009 Author Report Share Posted February 17, 2009 I have my maruzen m870 hooked up to co2 at the moment. Any chance for a video of the m500 shooting with co2? I've been thinking about doing this, I will now. Just need some free time and understanding neighbours Expect one soon Link to post Share on other sites
hessu75 Posted February 17, 2009 Report Share Posted February 17, 2009 Quick question: Does the ACM M500 have the gas reservoir inside the shottys frame, not rear stock or grip? I need to know this because I am also buying this M500 shotty, and going to mod it with tactical retractable rear stock. Did not get full understanding from this fine tutorial. Already have the Palmers thingys too from my earlier projects. Just wondering, do I need to drill the filling valve space bigger, if I have the rock barb from Palmers, which will thread in to the original filling valve threading??? I am going use the microline and 12g cartridge adapter from Palmers. Cheers -Hessu- Link to post Share on other sites
Fin Posted February 17, 2009 Report Share Posted February 17, 2009 Does the ACM M500 have the gas reservoir inside the shottys frame, not rear stock or grip? Its in the frame, on the pictures above were he drills the hole. Great article, im going to look into doing it. However (and this is going to sound like a huge set of very stupid questions) is it possible to run this on a HPA system and get it firing around 300-350ish Fps (any idea what to set the regulator for that?) Wanting HPA as i live in the middle of nowhere and there is no filling stations near me (Hoping i can use the same pump as i use for my air rifle (more adapters?)) Cheers Link to post Share on other sites
hessu75 Posted February 17, 2009 Report Share Posted February 17, 2009 IMO you can easily run HPA than Co2. Both setups need a pressure stabilizer, which can lower the bottles output to 100-1??PSI. More than that, you will break the weapon (this is with Escort). This ofcourse depends on the weapons internal parts, how and what material is used. You can run higher outputs, but as said this depends on the weapon at hand. I run my Escort MP5 with both power sources, HPA and Co2. Sadly I do not remember the parts manufacturers. But, they are well known to paintball enthusiasts. The smaller 12g rig is Palmers. You cannot use normal compressor to fill the HPA bottle. You need stronger compressor, because the pressure in HPA tank is very high. Test pressure is 500bar and the full bottle is 300bar. Thats like 2000 ´ish PSI. Or something like that, cant remember exact figure. Cheers -Hessu- Link to post Share on other sites
kizza Posted February 17, 2009 Author Report Share Posted February 17, 2009 You can use HPA and yes you can use an Air rifle pump, already tried this and the fittings are the same. My air rifle pump goes up to 250 Bar which is fine, depends what yours is? Link to post Share on other sites
Fin Posted February 17, 2009 Report Share Posted February 17, 2009 You can use HPA and yes you can use an Air rifle pump, already tried this and the fittings are the same. My air rifle pump goes up to 250 Bar which is fine, depends what yours is? Mine goes up to 250 as well, i think the brand is RWS and it came with a 'Falcon' brand air rifle. Hopefully it would work fine but i best do a lot of research into this as i hear those high pressure jobbys can go bang Link to post Share on other sites
kizza Posted February 17, 2009 Author Report Share Posted February 17, 2009 I'm pretty certain using a hand pump to pressurize a HPA tank is fine, as long as you don't exceed 3000PSI/4500PSI depending on the tank. I'm using the FX airguns pump link Link to post Share on other sites
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