DD-27 V2.75 Compact AST Rifle





Introduction: DD-27 V2.75 Compact AST Rifle

This is it. the one the only, the DD-27!. I have worked long and hard on this gun. It is the strongest to date firing pin type K'Nex gun. It works with the most frictionless-to-date barrel for ram guns. The barrel is more then 1 foot long, BUT it is only composted of 12 connectors. shoots the 7 1/2 in. grey rod.

V1.0- Made as something when i was bored, never took it apart.
V1.5- I modified it for some more power
V1.75- Added Perfect Duck's pistol grip
V1.9- Added a true trigger mechanism and a better barrel
V2.0- Significant changes to the front barrel were made, stock was added.
V2.1- Heavily fortified the front of the barrel.
V2.5- Added barrel extension to make it shoot greys harder then the other red rod ammo.
V2.75- Nothing big but i added a chain on the top

Believe me, the power of this thing is unrealistic and you will never truly understand the power without making the gun.

It gets all this power from three things.

1. The barrel does not have that much friction, it still has friction but with only 12 connectors composing the entire 1 foot 2 in. long barrel.

2. It uses the KILLERK pistol type mechanism were the bullet is held in exactly were the ram will make contact with it. But mine is better. There is 1 in. of space between the ball joint(note i used a light grey connector instead of a ball joint) and the connector before it. So the gun does not lose any power before the ram hits the ball joint. Normally it would hit the side of a connector and have to go through the hole in it and that would line it up with the ball joint. And then the ram has to push through the sides of the ball joint. With no connector before the ball joint the ram just glides over the the ball joint, not losing any power, but still hits the rod, firing the gun.

3. It has almost a complete draw back of the firing pin. The block is exactly one grey spacer after the tan lock that holds the ram back. If i moved the block one blue spacer up the firing pin could not be pulled back far enough for the block to engage. This helps because the firing pin has almost a entire grey rod length to speed up and gain momentum that ultimately gives the gun power.

standard round (grey rod)-80-100 feet
sharpened rod 70-90 feet
grey connector on grey rod -accurate to 60 feet!
2 3d blue 7 slot connectors with blue clips all over on it connected to grey rod- 40 feet shrapnel 10 feet away from bullet

stats were taken with two #64 rubberbands tied togeather.
ranges and power may vary.
Please comment and rate!!!

Step 1: Gather Your Parts

Parts list:*

grey-------------------------2(black recommend)

dark grey------------------16
light grey------------------5

tan locks------------------2(one needs to be weakened, see Perfect Duck's twin pistols to find out how)
black hands--------------18
ball joint ball-------------1
blue spacers------------21
grey spacers------------14
flexy yellow rod---------1


*Subject to counting errors

Step 2: Beginning of Barrel and Ram

This is a some what special part. it is one of the only guns that get a complete draw back of the ram. the block on this gun is right before were the ram can not be pulled back any more(a tan lock holds the ram in). So i get almost a entire grey rod length for the ram to speed up.

This as around the easiest part of the entire gun. You need to add tape to the ram, If you don't then you will have broken pieces when you fire the gun.

The one tan lock in the picture is the modified one.

Sorry about this being a big part, but it should not be hard, as this part is not complicated.

Step 3: Make and Add Handle

Not hard, this is the same as Perfect Duck's handle. Instructions are not that in depth because you can find them on perfect ducks instructable.

Step 4: Add Extended Barrel.

Most important part, this is what gives the gun its power. I explained it all on the intro so just make from the pictures. This is the longest step, i tried to make it as easy to make as possible but pay attention to what you are connecting.

Step 5: Extend Barrel Even More

Yes, the barrel gets bigger. We are going to add more to the barrel and a hand grip.

Step 6: Strengthen the Barrel

Add ons to the barrel. They make the barrel a lot stronger.

Step 7: Add Stock

Make the stock, its not the best but it works well, and looks cool.

Step 8: Add Trigger

Add the trigger

Step 9: Chain

Make the chain, and attach were noted in the picture.

Step 10: Ready, Aim, FIRE!

Just attach 2 rubber bands to the ram, and one to the trigger. Then pull the ram back, and push a grey rod into the light grey connector in the barrel. Then just aim and pull the trigger.

Don't get hurt like i did!



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Please be positive and constructive.




This thing is lethal - 271 feet with 12 64's tied into 6 strings of two... The pin exploded, but it fired!

Sorry, for me this did not get your claimed 100 feet, it only hit about 60 at max, and not just that but I had quite a few more bands than you and strengthened everything to a ridiculous degree. The gun is taken apart now to build my rifle, your gun was pretty bad, but going by your instructables, you lack pieces which might be the reason.

This gun requires the barrel to be completely straight or else it won't fire well. strengthening the barrel will only help if you make sure to keep it straight. I have many reports from people hitting higher then 60 feet, so the gun design isn't the problem. I'd check that all the snowflake pieces in the barrel are smooth, the firing pin is completely straight, the ammo is straight, etc.

Also, you have to make sure the bands are very balanced. If they are puling the firing pin even slightly to one side or the other that will seriously hinder performance.

You should also note, I have much much more K'NEX then is in this gun, butI don't see how that effects the gun at all.


The stock is so weak on this gun that a pin guide would have hurt the power more then helped it.

I seriously recommend building this gun without just because it's really bad. Now the next version of the gun that i made(the Ible for it is probably coming soon. I don't know, I've been saying that for who knows how long now....) has a pin guide because the stock is strong enough to not bend. In that case it probably does help a little, and makes the pullback easier.

Umm, well why don't you strengthen the stock. I'll add a (strong) stock and pin guide for you if you want? I'm good with stocks.

I've already done that on the new version which isn't posted. You can on your gun but I don't need to you do that for me.

Fine then, just hurry up and post it then. Does it have a pin guide? Also, put the chambering mech from the NAR on it.

Chambering mech? You mean the stray ball joint shoved in the front of the barrel to take the impact of the firing pin? I hardly call that a mech, and I'd never put one on one of my guns. It's just a crude way of taking the force. that ball joint will eventually break and it probably won't take that long.

I'd be allot more enthusiastic about the NAR if Ooda actually put some thought into how he dispersed the impact instead of shoving a piece in the barrel to take the entire impact force. 

Now you are just jealous because it is so much better than this. I have built it 4 times (I only break it 'cos I don't have that many pieces) and I know that it shoots 450+ft with 12 bands. The ball joint won't break, because it hits it side on, study it. There is no hole in the middle. Also, since Ooda put it on the nar, it has a pin guide, and a way better true trigger which blocks further back in the barrel than this.