Thursday, August 11, 2011

Mortar Pistol - Re-barrel Mod Guide!

This mod guide will look into re-barreling the Mortar Pistol to convert it from firing large foam "slug" ammo to firing foam darts.

For more information about the Mortar Pistol, read my review of it Here.

Okay, lets start the re-barreling process...

Step 1:

Open the blaster casing and separate the turret from the main body.

Disassemble all the turret parts.

Step 2:

Trim the machine screw ports inside the yellow barrel holder piece, this is to allow more space for the additional air tank-to-turret seal that will be needed to optimize performance.

Step 3:

Create holders to form a secure point to attach the new barrels.

In my example, i cut 13mm SingaPlastics PVC pipes into 6 pieces of 1cm length sections, then i glued them on with high strength 2-part epoxy glue. These PVC pipe sections are an air-tight slot fit for the 1 ft length PETG tubes what i will be using as barrels.

Make sure the epoxy glue has fully cured for maximum strength before use.

Step 4:

Cut out large slot sections at the back of the blue turret piece, this will allow the barrels to be rear loaded.

Step 5:

Install a ring of foam material to create an improved seal between the air tank and turret. I nested and glued the original nozzle into a 1/2" SCH40 Clear PVC pipe section, so that there is a secure base for the foam material to be attached on.

Step 6:

Put everything back together and its completed!

In my unit, i made an additional custom barrel spacer to further support the PETG barrels. It was created by cutting 6 x 1cm length 13mm SingaPlastics PVC pipe sections (to hold the barrels) and 3 x 1cm length 16mm SingaPlastics PVC pipe sections (to link the barrel holders).

All of the PVC pipe sections were then positioned and glued together with high strength 2-part epoxy glue to form a customized PVC "ring" design barrel spacer. :)

Here is a view of the rear loading slots from the left side of the blaster.

The Mortar Pistol fires from its top barrel, so just aim directly down the turret barrels to line up your shots.

With this simple re-barrel mod, the Mortar Pistol can now load and use foam darts. :)

:: Sample Test Fire Data ::

PTG: Parallel-To-Ground (Shoulder height, no elevation)
ATG: Angled-To-Ground (Aimed higher, 30 degrees elevation)

Distance is measured at where the shot lands (Average of 6 shots).

Air tank is filled up with 4 pumps using the stock pump.

Stock Mortar Pistol (Original barrels + Large Foam "slugs")
PTG = 15 ft
ATG = 20 ft

Re-barreled Mortar Pistol (1 ft PETG barrels + Foam darts)
PTG = 110 ft
ATG = 125 ft

Note that the tests were done under controlled conditions with custom calibrated foam darts. The results are sample estimates for reference (your results may differ depending on materials and mod techniques used).



I've managed to test the Mortar Pistol with a hopper clip too.

As i had already installed a 1/2" SCH40 Clear PVC pipe section around the front nozzle, i could just simply connect it directly to my hopper clip, which also uses a 1/2" spec PVC wye joint!

Here is a comparison between the 6-barrel turret vs the hopper clip.

Hopper clip assembled.

Due to the nature of hopper clips, they usually require additional adjustments and testing to get the right foam dart and hopper combination to match the blaster.

Ranges depend on the hopper clip length (and consequently the amount of clip deadspace), along with the foam dart fit in the hopper system. I get around 80-100 ft with my current setup (ranges reduce as the clip empties).


  1. hi sgn, did u test to muzzle velocity of this blaster? will this is mod make it game legal?

  2. mark loon,

    The re-barreled muzzle velocity is similiar to a similarly modded AT3K, around 220-240 FPS (depending on the number of pumps and the foam dart weight used).

    Whether it is allowed in Nerf games will still depend on the game organizers decisions. :)

  3. Where did you get one? I've been looking for one ever since it was posted on Urban Taggers.

  4. ScoutsIx-3,

    I ordered it from (an online shopping portal in China).

  5. How large is it? Is it like AT2K big or AT3K big?

  6. SeanMcD,

    You can see the scale comparison of it with a Nerf Maverick at the full review:

  7. Is it like a 3k or 2k in sizE?

  8. Where do you get your Clear PVC, Sch. 40 PVC, etc.?

  9. [slurpmonk],

    I ordered it from an overseas seller, i guess you could check at the various Nerf forums stateside and see if anyone has equivalent pipes available for sale.

    Or you could also just test out locally sourced pipes and see which can also fit too.

  10. Slight design flaw - you may go deaf when you fire the mortar pistol :)