GSO-Geko Posted April 27, 2014 Report Share Posted April 27, 2014 (edited) A lot of advice and stuff has been offered on the m870 thread seen here http://arniesairsoft.co.uk/forums/index.php?/topic/210618-tokyo-marui-m870-tactical-gas-tri-shot-shotgun-picture-text-and-video-review/?hl=%20marui%20%20m870 However, since the thing is now 30 pages long, I felt it necessary to create a thread specifically to collect all technical advice related to the gun. For starters, my three videos related to the gun. Disassemble https://www.youtube.com/watch?v=p3zD8GL9VBs Reassemble https://www.youtube.com/watch?v=xNsdjilxly0 Trouble Spots https://www.youtube.com/watch?v=F7u4qRz4-Zo Some tuning Advice To Increase FPS: A small Oring on the bottom of the hammer spring will increase the FPS by approximately 30 (or 10 mps if metric is your thing). Polishing the hammer rails will allow the hammer to slide forward much faster and smoother. No velocity change measured, but it can't hurt. If you're getting a consistent slow leak from the body. Most of the time the culprit is the expansion chamber. Take this thing apart and find this bit. I've found that the orings here are often dry. Means the valve won't close completely and cause a leak. Over time, this will completely ruin these orings. A little bit of silicon oil fixes this quite easily. For good measure, apply a bit of silicon to all the orings in the whole thing. Broken nozzle fix. This was a rough try at this, results are promising, maybe someone with more machining skills can do a better job. I noticed the top nozzle on my was totally fractured, rendered the gun unusable. So, a bit of 4 mm brass tube cut to length will provide support. I did have to drill out the nozzle a bit to fit the brass tube. Cut a little bit of that nozzle back And a bit of 5mm brass tube over that to replace the bit you cut back Make absolutely sure that the new "nozzle" is the correct length. If it's incorrect you'll get feeding problems and the gun won't be able to rack properly. As people ask questions and find solutions, I'll add things to this first post. Edited April 27, 2014 by GSO-Geko 9 Quote Link to post Share on other sites
Philbucknall Posted April 27, 2014 Report Share Posted April 27, 2014 (edited) Cool thread and great idea mate! Edited April 27, 2014 by Philbucknall Quote Link to post Share on other sites
ShinSeiki Posted April 27, 2014 Report Share Posted April 27, 2014 Great thread, kudos on the effort. Quote Link to post Share on other sites
renegadecow Posted April 27, 2014 Report Share Posted April 27, 2014 We need people like you for all the novel length reviews. Quote Link to post Share on other sites
Norotor Posted April 27, 2014 Report Share Posted April 27, 2014 Good idea, really appreciate it. The 30 fps increase with the hammer spring shimming, is that with green gas? Quote Link to post Share on other sites
GSO-Geko Posted April 27, 2014 Author Report Share Posted April 27, 2014 (edited) Kinda. I run it on HPA at the same pressure as green gas. I can get around 350 FPS with 0.25s. I was also under the assumption that, like my regional forum, I would be able to edit any of mine own posts for any length of time. Sadly, this is not the case. Edited April 27, 2014 by GSO-Geko Quote Link to post Share on other sites
renegadecow Posted April 28, 2014 Report Share Posted April 28, 2014 How often do people run across broken nozzles? I'm thinking shoving thin metallic tubes (like from a collapsible antenna) in each nozzle as a precaution. Quote Link to post Share on other sites
GSO-Geko Posted April 28, 2014 Author Report Share Posted April 28, 2014 if you have the ability, go for it, take pictures and post them here. i think the problem is very common for this model. Quote Link to post Share on other sites
GSO-Geko Posted July 10, 2014 Author Report Share Posted July 10, 2014 If you're getting inconsistent feeding. Make sure the selector spring is in the position shown here. Quote Link to post Share on other sites
mrsevenstars Posted July 10, 2014 Report Share Posted July 10, 2014 To clarify the selector spring is the large spring shown above that is around the brass tube? Quote Link to post Share on other sites
GSO-Geko Posted July 10, 2014 Author Report Share Posted July 10, 2014 (edited) Edited in response to your question, thanks! That other spring is the nozzle return spring. Edited July 10, 2014 by GSO-Geko Quote Link to post Share on other sites
mrsevenstars Posted July 11, 2014 Report Share Posted July 11, 2014 Thanks bud. Quote Link to post Share on other sites
GSO-Geko Posted August 11, 2014 Author Report Share Posted August 11, 2014 LOST BARREL BRACKET FIX So if you're like me, you use this gun a lot. And during use sometimes the black plastic bracket at the end of the inner barrels will fall off. And sometimes you will notice and find it, other time (non-plural) you will not. This is more of a problem with the SAT brand shorter barrel, as I think the internal dimensions are slightly wider. However, electrical tape fixes everything. First attempt was with a 4 layer think wrap around all three barrels. This made it so there was virtually no spread on the bbs out to 100 feet, or around 32 meters. While this allowed me to live out my dream of being like those guys that get around sniper limit servers on Battlefield 4, I needed the spread back. Thankfully with calipers and careful cutting you can wrap a 49 mm length of electrical tape around a single barrel almost exactly twice. This put the spread right back where it should be. And has just enough pressure against the inner wall of the outer barrel to keep them stable. Putting rails on the stock foregrip I purchased a G&P railed foregrip, but I found it to be too heavy and loose. Therefore, a rail on the stock grip became the best option. Using a G36 rail set I bought on ebay, first came attaching the rail sections for measurement and pilot hole marking with a silver sharpie. With the pilot holes drilled, I widened them out to accept an M3 screw. And countersunk the inner surface of the foregrip to accept the screw heads. And done. It's very sturdy and easy to do. Plus light enough not to ruin the run-around-all-day with it vibe. Picture above of full shotgun displays the finished result, and no, that's not how I run it. 2 Quote Link to post Share on other sites
GSO-Geko Posted August 19, 2014 Author Report Share Posted August 19, 2014 Loading Arm Fix So my feed arms finally broke... kinda. The posts on either side of it are bent down slightly, this means that the loading arm doesn't get pushed down enough to allow bbs to feed.And so workbench time.First step is to remove the posts themselves, but not completely, we need a location for the guide hole.Guide hole time.Slowly working my way up the bit size to completely remove the last post stump.I used a 4mm screw with the head trimmed off.Boom. Fixed. 4 Quote Link to post Share on other sites
DrAlexanderTobacco Posted August 19, 2014 Report Share Posted August 19, 2014 are you a wizard Quote Link to post Share on other sites
GSO-Geko Posted August 19, 2014 Author Report Share Posted August 19, 2014 are you a wizard Yes. 2 Quote Link to post Share on other sites
Wingmann Posted August 19, 2014 Report Share Posted August 19, 2014 Yes. Make me richer! Quote Link to post Share on other sites
GSO-Geko Posted August 20, 2014 Author Report Share Posted August 20, 2014 New and Much Brighter take down video. Sorry for the delay everyone! https://www.youtube.com/watch?v=ACqyBNpl_kg&list=PLPOpqBVMxBHsRwsQAXT3SCEJrx3KkxrZT 2 Quote Link to post Share on other sites
DeltaZero Posted September 5, 2014 Report Share Posted September 5, 2014 Question for you guys if I may! My Breacher has recently stopped working on 6 shot. It now only first 3 unfortunately! Can someone give me a hand to get it back up to speed? Could it be the selector spring? Quote Link to post Share on other sites
Habakure Posted September 5, 2014 Report Share Posted September 5, 2014 I think you'll have to open it up and take some pictures, so that people can see what has gone wrong. Quote Link to post Share on other sites
DeltaZero Posted September 5, 2014 Report Share Posted September 5, 2014 (edited) Not 100% positive on opening it up unfortunately.. did it once and managed to bend the loading arms, so am pretty hesitant now. Does anyone have an idea of possible problems before I go at it and crack it open? It just went from firing 6 to 3 over the space of one shell pretty much. Edited September 5, 2014 by DeltaZero Quote Link to post Share on other sites
Norotor Posted September 5, 2014 Report Share Posted September 5, 2014 Probably the loading arm posts; mine broke after a couple weeks and it would eventually only load 2 BBs on 6-shot mode. Quote Link to post Share on other sites
DeltaZero Posted September 5, 2014 Report Share Posted September 5, 2014 Doubt it will be that. It's got a pro-arms CNC aluminium part in there now after I bent them in my tactical. Quote Link to post Share on other sites
GSO-Geko Posted September 5, 2014 Author Report Share Posted September 5, 2014 Could be any number of things. are your loading nozzles aftermarket? Quote Link to post Share on other sites
DeltaZero Posted September 5, 2014 Report Share Posted September 5, 2014 No they arent. I don't think they wouldve warped already though, the breacher has only done 10 shells ish I would say! If its that I've got a nebula plastic reinforced loading nozzle as spare. Quote Link to post Share on other sites
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