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Echo 1 m28 project + piston mod

6799 Views 16 Replies 6 Participants Last post by  ~Ranger~
Hey guys I have been talking to Dragon64, reading his posts watching his videos and slowly but surely tuning my rifle. I figured I would post up the progress of my rifle thus far and I also wanted to post a piston mod that I stumbled upon earlier this week.
I am not new to the sport but I am new to modding BASRs and so far it has been an interesting and sometimes annoying journey. Real quick info on the gun I bought it used several months ago, it came with a masamune vsr-10 barrel, metal spring guide, element 145 spring, Harris Bi-pod and a madbull barrel extension.
I have since teflon modded the cylinder head, teflon taped the hop up rubber, installed 35mm film canister shim to the cylinder, edged the sears (started slam firing this repaired it for now as I await my sear set) and I modded the piston o-ring to provide better compression.
At the moment I can hit a torso sized target out to 250 feet with washed madbull .3gram bbs ( just ordered some .4 gram javelins)

The piston mod
Anyone who has opened their cylinder unit in the m28 will have noticed the o-ring on the piston and how loose and sloppy it fit and subsequently inside the cylinder their was a loss of compression.
I used Dragon64's method of putting teflon tape in the groove to take up the slack and provide a better seal, but after a little use I opened up the cylinder and saw that the tape had been removed. At a quick glance the groove looked similar in diameter to my faucet, so I grabbed one of the extra o-rings I have laying around for that and put it on, it fit perfectly but still didn't seem like it would reach the cylinder walls. So I then slipped the stock o-ring over my faucet o-ring and voila a nice tight fit that seems to give optimal compression. Maybe I could use a fatter faucet o-ring but for now these seem to work great.
I don't have a way of measuring the diameter with the new o-ring set up but I will figure that out in the near future. Also I am attending an event and will be able to post up the fps results when I can use a chronograph. I might try and do a before o-ring install and after to get a real idea of any improvements.
My range seems to have increased some along with fps but again that is just eyeballing it. Also I will note the sound the gun makes upon firing now leads me to believe it has some sort of boost in power.

I will post up pics tonight and let everyone know the type or rather size of the o-ring I used.
I would like to thank dragon64 for his extensive work on the echo 1 m28 and his input to me thus far without which I would have a really nice wall hanging m28 instead of the bb Beast it is becoming. :shot:
if anybody has any input or suggestions to my upgrades lay it out here I would appreciate any input.
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Isnt it crazy how far these things shoot?? I was amazed by mine! I am holding on to some of the parts to my dead M28, debating when money get back on track rebuilding it. Or maybe selling the parts, not sure yet,lol..
Thanks for providing this info. I just installed some new sears in my M28, so I'm ready to try and get it back out on the field. This sounds like the next step.
Cheesman says he is able to mill up m28 pistons by the way.. from aluminum!
Yeah the range is amazing on these guns, measured out to 300 feet they were making it within about 10 feet of my live target today ( fellow airsofter volunteered) at 210 feet they were hitting him everytime, and the furthest shot I got today was 240 feet. I want to get the IR hopup installed and my hope is it will give me that little extra boost to get it to 300 feet. By the way the test today was with the .3 gram washed madbulls... I don't really like the Madbulls so I am excited to test out the new .4 grams I will be getting on the 19th. Here are the pics of the piston mod, unfortunately I couldn't find the label on the package that states what type or size it is, most faucets will have a similar diameter.... I am guessing.

First pic is the faucet o-ring installed
second is a comparison with a dime to get an idea of the size I used.
third pic is the stock o-ring over the faucet o-ring


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This is an excellent and simple mod for the M28. When I was working heavily with my M28, and was trying to decide what to do with the piston, I employed a similar mod, but much less sophisticated; I filled the huge gap in the piston o-ring groove with white teflon tape:

The works great, but the problem is, the teflon tape gets 'gooey' and begins to deteorate from constant use, and will need to be removed & replaced (R&R). meshootyoubang's mod allows for a more permanent and consistant solution. Imagine how much pressure is being lossed through that "Grand Canyon" of an o-ring groove.

Yes, Cheeseman is offering to have made near stock replacement 45 degree pistons, made from 6061 aluminum. I'm down for one, and I hope that everything comes through, so I can test the piston out. A replacement piston is really what this platform is missing to be a nice shooter. Until thien, this o-ring mod is an excellent fix to help boost the fps of the M28 rifle.
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I did something a little different, instead of teflon tape (got tired of cleaning it off) or finding an O-ring that fit, I wrapped a couple layers of sinew I use to mend things that needs to be durable THEN replaced the original O-Ring.
hey guys, im going to try this on my piston until a new one is made, thanks! i have to replace my sears, and a few conponents in my trigger box would this be ok.
M28 pistons are currently being made. Me and a buddy are doing them. He has access to a machine shop, using a Cnc to make the pistons. I will have my protoype anyday now.
but will that sear set work? and heres what echo 1 said today...

"you can use the stock piston and vsr10 sears and be good to go. the upgrades from us are soon to be out. within weeks."
The m28 uses the standard vsr trigger box, the piston isnt the same cause the m28 piston is a bit longer. I'm glad their coming out with some pistons but that sure does screw me and my buddy super bad,hahaha.. Sunuva!:doh:
im sure they've said "with in weeks" 7 months ago.
Right, about a year ago they said it would be soon.

My prototype piston is finished,now I just have to go get it from him. The pics he sent me look awesome! I will keep everyone posted.
well if it works, and i don't have to give you my arm, i'd buy.
Lol.. right on. I just told my buddy. He recently was bumped to day shift so his schedule on this is sorta changed cause theres more bosses around. I will have my piston probably sunday on my way to the game, I will test it out.
Sweet! let me know how it works!
For sure I will buddy. I'm way excited to get mine,lol.. I kinda wanna go pick it up now but hes lives about 45 minutes away and I cant move around real good today. "Back locked up"
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