The easiest tweak is a short length of soft automotive vacuum line slit lengthwise, then taped to the cocking lever. Makes cocking much more comfortable.


I am not sure how this happened on an otherwise good design. Perhaps they used a larger screw later in production. On my pistol, the screw threads extend into the bolt groove, causing the bolt to drag which causes loss of velocity and accuracy. It also can damage the bolts. I used a round needle file to bring the threads down flush with the groove. However, this made scratches in the black finish. Might be better to remove the screw to do that.

Accuracy You can increase accuracy by testing the bolts in the groove. Press down on the front of the bolt. If there is a gap, then turn the bolt over and try again. If it lays against the groove, use an indelible marking pen to make a mark on the underside of the bolt tip so that you can always get the bolt inserted so that the nose does not stick up.

While we are checking bolts, make sure the tip and "feathers" are firmly attached. I use a small drop of Gorilla Glue, or other polyurethane glue. It expands as it sets.

When you install the bow into the stock, measure the distance from the tips on each side to make sure the bow is centered. I am not sure if it was recommended in the instructions, but I have a couple of layers of electrical tape wrapped around the bow where it is clamped into the stock. A scrap of leather would be even better.

With the bow strung but not cocked, the string should form a 90° angle with the sides of the pistol. If it is not square and loosening and re tightening the bow retaining screw does not correct it, put one or two strips of paper under one side of the bow where it contacts the stock.


You can gain a slight increase in velocity by bending this spring upward to reduce drag. If you bend it too much, accuracy will suffer. Simply bend it back some if you need to.


This may be your best bet for accuracy improvement. Remove both the front and rear sights. If the bow is strung, cock it and put the safety on. Wrap a small piece of 600 grit 'wet or dry' silicon carbide paper around one of the aluminum bolt shafts or something else 1/4" in diameter (like a drill bit). Lightly sand the edges of the bolt groove. This only takes a few seconds and you should be able to feel the groove edges where it contacts the bolt getting smoother. Do the full groove length.

After doing this I put 4 shots in the same hole at 15 feet.


Broadhead bolt, or quarrel (4-sided head)

A length of fiberglass arrow can be used to make broadhead bolts for your crossbow pistol. The shaft must be longer so that the broadhead sticks out in front of the pistol. Do not use a good saw to cut the fiberglass. I guarantee it will be ruined. Or use an abrasive cutoff wheel on the hand grinder. Don't breath the dust.

Fishing Crossbow

Like to fish? These barbed bolts are available on eBay.


Folding Shoulder Stock

This folding stock was made from 3/16 steel rod and two heavy solder type copper terminal lugs meant for electrical work. The lugs can be epoxied or soldered on. The 90° bend at the butt was made by heating the rod with a pencil tip propane torch, then bending in a vise. Note that having the stock folded does not interfere with using it as a pistol.


Open, it adds greatly to stability and makes hitting small targets easy.
UPDATE  I filed the underside of the screw head and soldered it to the copper lug. That prevents the screw from turning when you adjust the wing nut.

An operation analysis
I experienced string jump-over a few times, especially on short bolts. The point where the string contacts the rear of the bolt resembles this:


It may be possible to file the rear of the channel to center the string at the center of the bolt. I made the channel slope in the area 1.5 inches from the rear where it is slotted to a bit over 1/4" wide; there is no support for the bolt in this area. This made the string contact the bolt rear at mid height.


Safety too stiff?
On my pistol, it took a great effort to put the safety on, and a Herculean effort to side it off. Make modification at your own risk!

Removing the sheet metal covers reveals the safety bolt. Be careful not to lose the shiny metal tube, two small springs, or detent.

Safety bolt
The red arrows point to the two grooves that engage the spring loaded detent.

Safety Detent
I used sand paper to change the shape as above. If you try this, only remove a little material at a time, then try it for fit. Your thumb over the detent will (hopefully) prevent it from flying out as you fit it.

Now I can flip it back and forth using only my thumb instead of both hands.

Lubrication
I tried bees wax as recommended for full size crossbows. It created way too much drag. Chapstick worked better for me.  Squeezing the two cocking prongs gently together showed that the cocking rod needs lube too. A little chapstick on the sides where the rod contacts the frame reduced the amount of effort to cock it greatly.

Repeating Crossbow Pistol

Okay, I had to do it. Not shown is the magazine follower. It holds 6 shortened bolts in this configuration (above). Several problems were solved doing this: string pop up that hops over the bolt causing misfires. String oscillation that robs power. The stack prevents the rear of the bolt from dropping which results in wild shots.

Short bolts have more initial velocity which gives greater penetration and less drop at a distance. But there is a problem. Shortening the bolts exaggerates flaws in manufacture and many may not fly straight.

NEW
I wanted to try real feathers in the crossbow pistol, but needed some way to align the feathers accurately. I came up with this idea.

A scrap or plywood was chosen longer than the bolts. Four long grooves were cut using the table saw. I got lucky the first time and the bolts fit perfectly with the bottom of the bolt barely touching the bottom of the groove. If it had not, then I would simply sand the top surface. The red area is beveled slightly to make room for glue, and the finished fletching tool coated with floor wax to prevent glue from sticking. The weight is about 4" long of oak. Use what scrap you have on hand.

After I made a few bolts with feathers, it occurred to me that this tool could also be helpful for making the broad heads. Now it is easy to get perfect alignment of the razor blade in the slot in the bolt tip.

In tests, the feathered bolts do penetrate better than the plastic fins on the factory bolts. I assume this is because the velocity is higher with the reduction in weight at the rear.


Plans for this gem are now for sale on this page cheap. It uses standard bolts.