The cool part is the breech-loading for the giant marshmallows; I wanted to keep that function. With the current supplies on hand, that also meant making my first brass breech!
To undo the front off the blaster, you can depress the two pegs on the slide. The front will come straight off.
Now we take a section (I had a foot) of 9/16" brass, and mark it. 2 cm from the end, and then 1 3/8" long for the cut. Use your dremel, and have at it. Also make sure to deburr/polish smooth.
Now, take your dremel and remove the air restrictor to open up the airflow. Put a 2cm section 19/32" brass on the small end of you 9/16". Put 2cm of Sch. 40 1/2" PVC around that. All 3 pieces should be superglued together. Now shove it as far into a 1/2" PVC coupler as possible. Finally, put lots of hot glue around the inside edge of the housing, and quickly place the barrel in the opened-up blaster. Note that no dart stop is needed; the housing for the spring-loaded slide pegs sits directly behind the coupler and prevents my darts (1-1/2" single bb stefans, for future reference) from sliding all the way back). You can seal up the remaining holes with a thin layer hot glue.
Superglue 9" of 19/32" brass into about 11" of said PVC, and wrap the end in duct tape. Due to the shaping of the front of the marshmallow blaster (a faux rifling of the plastic to spin the marshmallow), this is by far easier than carving out the front with a dremel.
Place this piece on the barrel, and shove as far back as possible. Then with everything in place and in the "locked" position, hot glue the shit out of the front to fuse the barrel cover and front piece together.
Now you have a brand-new blaster to play with. Gets BBBB ranges, plus it has VERY quick pump strokes and a breech.
Technically, this costs twice as much as you need to pay for performance of this type (Got it for $20, as opposed to the mere $10 on a BBBB). But it's good, nonetheless.
Thoughts, questions, improvements?
Edited by Buffdaddy, 02 February 2011 - 09:28 PM.