[dragon64]

Echo 1 M28 Technical

The M28 platform came out two years ago, and filled a void left by the lack of CA M24 rifles, as an affordable M24 platform. This rifle was released alongside other variants of the M24 platform, like the Snow Wolf and JGW versions, all of which helped to fill in the voids. The M28 generated rave reviews when it was released, with its low pricing and its available options.

Now, generating a lot of negative press, the M28 is developing a rep as a platform to avoid. Even I have advised people against this rifle, as the rifle will surely disappoint anyone not ready for the technical problems that have plagued it since its inception. From a technical standpoint, I would like to re-evaluate the M28 rifle, looking at its good points and its faults and try to get the most correct and current information available. The information will be presented as plain and as clear as possible, in hopes of clearing up some of the bad karma that has been generated over the last two years.

Thread rules: This thread is intended for technical issues, and problem solving. We will look at the latest parts available, and learn how to make do with the proprietary parts in the rifle. This is not a CA M24 or VSR-10 or JG BAR-10 comparison thread, and we will not make any distinctions between the different platforms. Since many of the parts of the M28 are proprietary, this rifle platform should be treated as a separate entity all together. Pics and video are a must and are highly encouraged

M28 Availability:

The ECHO1 M28, after two successful years on the market, can now be had in two colors, the standard black, and now desert tan. And yes, the rifle comes with the following accessories as standard issue:

• Two magazines
• Harris style bi-pod
• Barrel extension adapter
• Tight bore barrel (6.03)
• (3) Barrel Spacers

Most of the top retailer such as Airsoft GI, EVIKE, Airsplat, Airsoft Atlanta and Pyramyd Air carry one or both variants of the rifle. There are many more venders, just too many to list, as they are easily searched online.

One more thought, Airsoft GI and Evike have well stocked "Boneyard" links on their website that a player could pick up a spare M28 for parts. The cost is usually half that of the original. The stock and outer barrel are worth that price.

Known Issues:

• Plastic magazines miss-feed and poor fit
• Slam-fire
• Bad Hop-up rubber
• Loose trigger sears (directly related to slam-firing)
• Bolt handle breaks off at cylinder crimp location
• Bolt / cylinder outer shell damage caused by out of spec receiver centering rings (may also contribute to slam-firing)
• Some parts are proprietary, thus no aftermarket support

Currently Available Upgrade Parts:

• 6.01 Barrel (Airsoft GI): http://www.airsoftgi.com/product_info.php?products_id=7577
• Optional Source For Masamune Barrel (Airsplat): http://www.airsplat.com/Items/AC-UPI-AA-515-1.htm
• Trigger Group (Airsoft GI): http://www.airsoftgi.com/product_info.php?products_id=7694
• VSR-10 Trigger Sear Group (Airsoft GI): http://www.airsoftgi.com/product_info.php?cPath=362_364_651&products_id=595 1
• Optional Sear Group (GI Tactical): http://www.gitactical.com/product_info.php?products_id=5951
• Optional Sear Group (EVIKE): http://www.evike.com/products/35657/
• Tunable Silver Trigger For M28 (Airsoft GI): http://www.airsoftgi.com/product_info.php?products_id=12145
• Tunable Black Trigger For M28 (Airsoft GI): http://www.airsoftgi.com/product_info.php?products_id=12144
• Metal Magazine (ECHO1): http://www.airsoftgi.com/product_info.php?products_id=8329
• Optional Source For ECHO1 Metal Magazine (Air Rattle): http://www.airrattle.com/ECHO1-M28-Metal-Sniper-Mag-p/mag-echo-m28-mtl.htm
• R Hop or any one of its variants.
• Speed Airsoft Custom Bolt Handles: Speed Airsoft M28 Bolt Handle ( Black ) by: Speed Airsoft - Airsoft GI Speed Airsoft M28 Bolt Handle ( Silver ) by: Speed Airsoft - Airsoft
• Speed Airsoft Bi-pod Rail: Speed Airsoft M28 Sniper Bipod Rail ( Echo1 M28 ) by: Speed Airsoft -
• Speed Airsoft Cylinder Tool: Speed Airsoft M28 VSR-10 Cylinder Tool by: Speed Airsoft - Airsoft GI

Note, EVIKE was marketing under the Matrix name, some cylinders and upgraded pistons, but these parts have proven to be somewhat unreliable and incompatable regardless of the description. For this reason, they are not included in this update.

 

[dragon64]

I'm going to follow this too... I have a pair of E1-M28's with new cylinders, pistons and springs. Be watchful over the cylinder, both guns had failed with cylinder issues independent of the piston.
I added the BV3/BV7 upgrade kit, it has performed flawlessly. One note, the FPS remained > 530 with the entire kit installed, but with the STOCK spring in the kit, the FPS was ~400 - 420. With the stock spring, they are 'legal' at most arenas. If I can figure a way to pull the catch pin and pull the cylinder without complete disassembly, then a quick swap is possible.

BV3/BV7 upgrades? Could you elaborate please?

 

[dragon64]

That's what happens when your memory is reduced to flash-backs...
I meant "WELL Spring Rifle Upgrade Kit (for MB03/MB07)". The piston is a little shorter than the M28 piston (but it's aluminum, not plastic) but the spring is a bit longer to take up the slack. I have it in both M28's and they've been shooting great!

You are going to have to go into more depth on this mod, as I tried to do this, but the piston would never engage the sear:

 

[dragon64]

I have owned my M28 for a couple years now. I bought it new from Airsoft GI months after it's release in 2010. I know this rifle inside and out. Recent topics around the internet, and the prospect of a new piston coming online have moved me to bring my M28 back into service. I am going to clean, rebuild and update my rifle to bring it back to tip top working condition.

While awaiting a key part, I have broke down my rifle and begun cleaning all of the old silicon grease off, and removing all of the teflon tape. My M28 will be like new when I am done.

 

[dragon64]

Here's the upgrade in action:
All I did to the kit was to NOT use the bearing kit included. Every time I attempted to use it, the sears would NOT catch. I suspect this may be the problem you've had.

That may be the key, is to omit the bearing guide parts.

 

[dragon64]

Yeah, now the only weak link is in the cheep metal of the cylinder. Both my M28's had bad cylinders, and were replaced with original Echo1 units I found on eBay. The stress of the heavier springs will take its toll on the pressed fittings for the bolt lever. I'm not looking to steal ~Ranger~'s thunder on his pistons, they are PERFECT replacements. Now if we can get him to make the cylinder in stainless steel, I'd be the first to order a pair of them.

Some M28 owners have told me in no uncertain terms, that downgrading the spring was a poor move on my part. But until there is a replacement cylinder available for the M28, the M130 spring will help make lighter duty of wear and tear on my rifle. With .36 ammo, I am still hitting the high 300's and low 400 fps range. The bolt, which is original to this rifle, cycles easier and still works great.

When I was shooting this rifle alot, I maintained it regularly. I pulled everything down that used lubricant and cleaned it all off and refreshed it. Why? Because the greease would turn that nastly gray color, which means it is contaminated and needed to be replaced. This is not unlike changing the oil in your car. I also changed out the white teflon tape everytime I maintenanced the rifle. Still, if there was a quality cylinder on the market right now, I would definitely pick one up.

 

[dragon64]

Besides the purchase of a new piston from Ranger Customs, I just now purchased a 'stock' M28 (OEM) hop-up chamber off of Amazon.com. My hop-up unit developed a stripped screw a couple months after I got the rifle. I manage to keep the hop-up in working order, but I figured it was time to replace it... again, this is one of those proprietary M28 parts that have no after market support.

Once everything comes together, this rifle will be at the top of it's game again.

 

[dragon64]

This has been posted on ~Rangers~ piston thread, but I wanted it captured here on the technical thread:

Take a look at this video posted by Brian, the Echo1 USA lead tech. The video shows Brian repairing an M28 that is slam-firing. He replaces the trigger sears first, then the piston, and wala! The rifle is back in action... then watch a little further as he replaces the trigger assembly and piston with a 90 degree trigger assembly and pistion, that he says will be sold by Echo1... good stuff, here is the video:

http://www.brianatecho1.com/videos/h...-vsr-10-parts/

Here is the kicker; this video came out in May of this year, and as of this posting, I have not found any of the 90 degree parts available... but I'll keep looking.

 

[dragon64]

You are correct, for the stock configuration of the M28, the 90 degree trigger is over kill. These products are for the upgrade hungry players that require them for high performance builds.

 

[dragon64]

My friend's JG Bar10 is using a M170 spring with a 90 deg sear and piston set but his range and accuracy is no better than my stock E1 M28 with a M120 in it. I can still hit a man size target easily at 250 to 280 ft with very little effort pulling the bolt back on my M120.

He has to struggle every time he pulls the bolt with the M170.

I was using an M130 spring in my rifle, but with the new rebuild, I am going to re-install the stock spring. I do not care for hard bolt pulls, just to up the fps. I'm all about accuracy and reliability. The heavier springs have too many inherant issues to warrant their services. I have never tested maximum effective range with my M28. I will after this re-build. I am planning a whole new set of videos just on the M28.

 

[dragon64]

You make the parts, and we will test them... Do you have a youtube channel to promote? As I rebuild my M28 and start a new series of videos on the rifle, I would like to give shout outs to your website and channel...

I found some archive video footage from Dec 2010, the month I received my M28, and posted it to my youtube channel... one of the first vids I made after doing some do-it-yourself mods... Don't know how I missed it... one of the few times that Alabama had such a beautifull snow fall... or any snow at all for that matter.

 

[dragon64]

I emailed Brian (Lead Service Tech) at ECHO1 USA about the zero trigger and matching piston, and his reply was that ECHO1 was having them made, and they have been trying to source materials and parts... no ETA on these new items.

 

[dragon64]

Dragon I have been watching your m28 vids since they came out Please do make new continious videos because I too want to get my m28 back in action but my hop up unit is terrible. I might take your advice and buy a new one.

Good for you CA. My wife asked me what I wanted for Christmas.. as ugly as it is, I may opt for the desert tan M28. We'll see. I have been watching the boneyards for a tan one to show up, it is at least worth half price to me if it comes with most of the accessories. More video will come once I have finished the rebuild.

The hop up unit issues is with the cast metal pin that the hop up lever pivots on.

Dragon, if you take a caliper you will find that the left side of the lever pin has a larger diameter than the right side. This is because the left side of the hop up unit needs to release from the mold and if the hop up lever point was completely parallel, it will bind coming out of the mold.

Mathematically you can calculated the exact angle of of hop up lever tilt from the measurements.

Thus the hop up lever will be canted a few degrees to the left, cause more hop on the left side of the buck, and a result shots hook to the left.

Solution - get a CNC hop up unit that using a real steel pin

I believe I lucked out on my recent purchase. I measured close to the base...

And closer to the top, and my pin is rather uniform...

The problem with the pin on this new unit, is that it does not extend to meet the other half of the hop-up shell. There is a 0.0625" air gap between the end of the pin and its mating side. I have a little more fitting and sanding to do, and then I casn re-assemble... not enough hours in the day.

 

[dragon64]

The #1 Complaint With The M28... is the Dreaded Slam-Fire event. Until this issue raised its ugly head, the previous #1 issue with the M28 was the propietary assemblies, namely the cylinder group and the hop-up assmebly. This will be covered in more detail later; today's topic is the new #1 issue to plague the M28, and that is the slam-fire event.
Again, for those of you just starting out, the slam-fire event happens when you cycle the bolt, and when you go to return the bolt to its fire position (battery), the bolt slams forward... wala, you have the nasty slam-fire.
There are a number of theories out there about the exact cause with regards to the M28, I aim to describe the problem that caused my rifle to start slam firing. The issue with my rifle lies within original M28 trigger group. The major components that make up the assembly rattled back in forth inside of the housing. The parts, which are generaly cast pot-metal, were made with very loose tolerances. So loose, it was a wonder that the trigger sear ever held onto the piston in the first place. As seen in the next photo, the wear on the piston sear shows clearly the rounded edge...

The piston sear flopperd around so much that when the bolt was cycled, the slot in the bolt was cutting into the side of the sear. Notice also how the metal looks almost pewter or even the color of lead. Pot metasl equals bad material for airsoft, unfortunately it is how manufacturers turn out quick down and dirty clones...

Here is a brief video on my defective trigger group. Although the video is of poor quality, I am able to clearly show how bad the M28 trigger can be...

There is an easy fix for this issue; if you are experienceing the slam fire event, and you believe that your trigger group is the problem, simply rebuild the trigger group... The downside is, it will cost you at a minimum of $55 for the parts. For my rifle, I rebuilt the trigger group using Airsoft GI's VSR-10 trigger sears and springs. The cost was $55 plus shipping. There are other manufacturers that make after market trigger parts for the 45 degree piston sear set up, you just need to shop around. I liked the Airsoft GI rebranded parts, as it comes with excellent spring package. You will find that the springs in the M28 trigger group are sub par, and need replacing. Here is the link to the parts I used:
http://www.airsoftgi.com/product_info.php?cPath=362_364_651&products_id=5951
Note also, if you are not comfortable rebuilding your own trigger group, then Airsoft GI has a complete upgraded trigger assembly for the M28, just remove and replace (R&R). Here is the link:
http://www.airsoftgi.com/product_info.php?cPath=362_364_651&products_id=7694
For those of you who seek the adventure and want to know more about what makes your rifle tic, here is a simple video I made on re-assembling your trigger group after rebuild. It is good to note at this point, that a trigger assembly from most any VSR-10 rifle will work in the M28. This is a blessing, as had this been one of the propietary assemblies, our rifles would have been dead in the water with no fix relief. As it is, this is the only complete VSR-10 compatable assembly that works as designed in the M28. Here is the re-assembly video...

With any introduction of a new part, there is a break-in period, until the parts start to messh and begin working together. Give your new assembly some time, and it will work like it was supposed to in the first place. Brian at ECHO 1 USA has indicated in I video that I linked to, that there is a zero degree trigger and piston on the horizon... unfortuantely there is no release date set.
If you have found that your M28 is slam firing for a different reason, please feel free to share what the problem was, and how you went about fixing it.

 

[dragon64]

I'll float one more issue that contributes to slam firing. Inside of the receiver are two plastic rings. The front ring is complete, and the rear ring has a gap in it. The rings help keep the bolt assembly centered within the receiver. But I have noticed that the rings in my m28 are a very loose fit. I was ablt to cock my rifle, and with some slight upward pressure on the bolt from my thumb, I could lift the bolt and the rifle would fire. Essentially I could fire the rifle, beause the slack in the rings allowed me to lift the bolt and piston off of the trigger sear.

I fixed the rear ring by manicuring an old 35mm plastic film canister which I used to replace the rear ring. Cycling the bolt was a little tight at first, but it is wearing in now... Check it out:

 

[dragon64]

I had to really dig to find the one I used... We used to have them in every drawer in the house it seemed.. not now, now the cannisters are a dying breed.

 

[dragon64]

New product from Dragon64. 35mm cylinder sleeve kits coming soon....

One drawback to the sleeve, and it is not really that big of a drawback, and that is that the sleeve needs to broke in. Because of the material, the break in period can take a while. I guess what I am saying is, the bolt will be tight to pull back on, until the sleeve gets a little wear on it. Silicone grease really helps with bolt cycling.

The plus side of this modification; my bolt is not getting damaged anymore, and it is well centered inside of the receiver.

 

[dragon64]

I wonder what their inventory looks like... The canister pictured in the link you provided will not work as it is the 35mm cannister with the screw on lid. You need the cannister with the pop-on lid. That way you can take advantage of the lip at the top of the can. I'll bet a call to the vendor when you order may net the cans you really need.

 

[dragon64]

I think I may be able to offer some help to anyone trying to fit VSR cylinder parts in the M28 as this is how I finally fixed my personal slam fire issue.
Budget VSR pistons will usually fit in the M28 cylinder, though some, like the ASGI piston I used, may need some filing/sanding to make them fit since the M28 cylinder seems to be a bit narrower than a VSR. Once you get the piston in though you won't be able to pull the bolt back far enough to engage the sears. This is because the M28 spring guide is about a quarter inch longer than a VSR guide so the piston hits the end of the spring guide before it reaches the sears. All you have to do to remedy this is to cut the spring guide down a bit or just use a VSR spring guide.
A VSR spring guide and VSR piston will work or an M28 spring guide and M28 piston will work but they cannot be mixed.
In my case this seemed to boost my FPS since the shorter piston has more room to accelerate than the stock one but i cannot verify with actual chrono results.
Now all I have to do is figure out how to get her to feed consistently.

For the miss-feeds, get the metal magazine... zero miss-feeds to date.

Interesting about the VSR-10 piston working. The one I tried would not engage, as the piston is nearly .25 too short, and just misses the trigger sear. When I installed the piston, I also used the associated spring guide, not the M28 guide... no joy.

I'm your has oulled through, no pun intended... I have wanted to try the Airsoft GI piston, but did not want to waste the money if I thought it would not work.

Do you have some pics of your psrts and set-up?

 

[dragon64]

Would this barrel listed on Clandestine work on the M28? It's just the length I was looking for (well 1mm short, but close enough).

http://clandestineairsoft.com/index.php?main_page=product_info&cPath=1_34&products_id=340

That is a little over 4" longer than the stock M28 barrel, are you tucking the rest into a barrel extension (mock suppressor)?