Resurrecting The Dead - TightAss Build No. 3

Once again in the spirit of taking on a challenge I have on my bench a very low end blaster to see what can or can’t be made of it.

Bing Feng M870 pump action shottie

First impressions, straight OOTB this is a shocker in anyone’s language. It features :

Full nylon construction, pretty solid.
Two alloy barrels, yes it’s a double barrel inner.

Manual pump priming.

Janky spring loaded gel magazine / tube that requires a pistol loader unless you want to chase errant gels around your shed all day.

Apart from the above, SFA.

Can’t give a chrono reading as it hasn’t successfully fired a gel out of either barrel :rofl:

Tearing it down, probably losing one of those barrels and attempting to make it feed with a half decent FPS.

Why do I do this to myself? :rofl::rofl:


Keep the twin barrels if possible.
If it’s anything like the M203, it’ll be fun.


I have a feeling it’s an M203 in formal attire :laughing:

I’ll get it hootin’… for $25 how could I say no? :rofl:

Jesus $25?! Steal. I’m watching this one fo sho!

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I paid $25 for the M203 with no handle!
Not easy to chrono though.
Have to divert one barrel or it confuses the sensor.

Impossible to chrono when nothing exits either barrel. :rofl:


Im pretty sure @CaptainAwesomepants had some luck with these.

I dunno… couldn’t find anything on here about the Bing Feng version with a forum search. Lots about the Alpha Kings.

Think I’m in unchartered water here… right where I like to be. :rofl:

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Well, if nothing else, you have plenty of spare parts.
That lower guard looks like one from another blaster.

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Weird arrangement in these shotties…

Double t piece and barrel, double nozzle on the cylinder head.
A quick check of compression out of the blaster showed no seal at all. Changed out the thin o ring for a thicker one, packed out the front half of the head to accomodate the thicker ring and filled the front holes on the piston head. It’s not like vacuum’s an issue with this manual. Got decent compression.

Reassembled and tested. It actually fired a couple of gels with each pump but a bit of confetti now and then. Teardown showed a lot of smashed gels outside the tube and t piece so both of those will be getting a bit of a shiatsu.

Interesting to note that every demo video of these shows the mag tube inserted into the blaster with the spring latch side facing upward. Supposedly you load up the tube, push it into the blaster and away you go. There is a tab inside that automaticaly releases the spring but it releases too early and smashes gels around the t piece. Have to look into that.

I’ll be working on that gap to the t piece, I suspect it contributes to the smashing of the gels.


The holes in the pistonhead force air behind the o-ring, pushing them harder against the cylinder wall for an even better seal.


Yeah… usually. I couldn’t get any kind of seal with them open. I figure a slow manual won’t suffer too much on the back stroke.

It ain’t over until the obese woman warbles… it’ll be revisited. :+1:

Is it basically the same internals as your M203, Cruise?

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Only thing similar is the offset spring guide.

Well you triggered my OCD and I just had to revisit that o ring. :rofl:

The o ring OD is smaller than the piston head diameter… maybe someone in the BF factory shoved the wrong o ring in on assembly, who knows? Zero float too, tight in the recess.

I stretched that puppy out a little and shimmed the front of the piston head to give it some movement. Joy… it shoots gels. Poor FPS around 120 which I think is nozzle engagement, and doesn’t feed consistently so more to do there.

But I thank you @Cruise for making me get off my arse and look at it again. I’m heading in the right direction. I’ll find the right o ring tomorrow, source a heavier piston spring and try to sort the feeding issues out.

Not tonight, last reassembly had me wondering why gels were just rolling out of the barrel… then I spotted the t piece and barrels sitting on the table… :rofl:

Time to wind it up when stuff like that starts happening👍


What OD/ID is the O ring bud? I just pulled apart an older piece of shit to find that it not only has a molded piston head (urgh) but an odd sized O ring. There are flourine O rings of all different sizes so I’m going to get me some so I’m not left short on these ‘left field’ builds…

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Sorry mate, just read the whole ‘I’m not doing anything else tonight’ part :joy:


I’l measure it up tomorrow for you when I take it out to go on the hunt for a replacement… it’s bigger than a standard piston o ring.

Then again, I may have a meaningful conversation with Austin Nichols and rip it out tonight. :joy:

I’ve been known to do that. :+1:

I designed and printed this li’l jobber. It basically “sorts” or separates the gels as they come from the janky spring-loaded magazine up into the t-piece. I noticed that no matter what I was shredding gels, then I realised that even IF they made it up the j-shaped t-piece and were able to be pushed by teh nozzle into the barrel, they wouldn’t be aligned. The misalignment was likely smashing whichever ones made it up there.

So I made this piece to guide them up in a straight line as gelgod intended. It’s hard to get it inside the existing t-piece without snapping the top bit off, but it glues back on so it’s not that bad.

Hit me up if you want the STL and you can give it a twirl. I also made the design public on Tinkercad:


I was really holding back at getting one of these. I really really wanted one but had heard they were just ornaments basically. I think I have excuse now.

Man, that’s some impressive designing right there. :+1:

Sadly I don’t have a 3D printer or access to one, so for me it’s going to come down to Kleenex, spit and superglue… as usual :joy:

You’re right, it’s a terrible feed design but slowly it’ll get there. Can’t really sort out FPS until it feeds consistently. Repositioning the mag tube so it doesn’t release too early has made it a lot better. :+1: