I've had a total turn-around of opinion with respect to aftermarket bolts in the Autococker. It had been my opinion previously that aftermarket bolts were a waste of time and money. No longer.
- Stock bolt
The stock bolt is a fine bolt for 90% of the players out there. It works well. The only case where it falls a bit short is in low pressure Autocockers where it can prove to be too restrictive to allow good velocity or good efficiency.
- ANS 10-hole bolt
This is a very free-flowing bolt, and until the Lightning bolt came along, was the best bolt to use with low pressure systems. It used to have the problem that it was milled down so far over most of it's length that it could wiggle from side to side when the ´gun is cocking. Over time, this put shear stresses on the thinned down shaft which could lead to it snapping in half. Since then, ANS has recognized and corrected the problem by putting a full-diameter island near the back of the bolt to prevent lateral movements.
- Bob Long Cyclone bolt
This bolt has a slanted inlet much like the Lightning bolt. The difference between this and the Lightning bolt is that the Cyclone has a huge, flow-restricting insert. It has been found to work with low pressure systems, so it isn't as restrictive as, say, the Menace bolt, but it is still not as free-flowing as the Lightning. The only person I know who uses one of these took the insert out.
- Bob Long Hydra bolt
I used to recommend this bolt as the only decent alternative to the stock bolt. My reasoning was that since it came with replaceable heads, companies would start putting out faces to fit this bolt, giving you may low-cost options down the line. Well, several years have passed and still only the three not-too-impressive faces that come with it are available. Bob Long hasn't even come out with a Cyclone face for this bolt. It's dead, Jim. Don't bother with this one.
- Evolution bolt
I used this bolt in my Evolution Minicocker for a long while and loved every minute of it. It isn't as free-flowing as the Lightning bolt, but it's better than the stock bolt. Additionally, it effectively buffers the air blast to reduce ball breakage, particularly with old and thin-shelled paint. I can't explain it, but something about this bolt just feels good when using it. The 'gun feels like it's casually easing the ball out of the barrel. It's also a very quiet bolt. Finally, I really dig it's quick-pull pin system which eliminates the ball bearings from the pin. If you aren't concerned with the lowest low pressure operation (my Evolution runs perfectly well at 290 psi out of the box - pretty low, but not the lowest), I highly recommend this bolt. The only caveat is that it's rather expensive when compared to other aftermarket bolts. They are available from Belsales/Smart Parts.
- Lightning bolt
This bolt from AKA Performance Paintball is one of my favorites. It has an inlet that angles forward towards the front of the bolt and then cones out towards the face. AKA claims that it results in a more laminar flow that is as easy on paint as any venturi design. What I know for certain is that it is one of the bolts that offers the least impediment to flow and so allows you to drop your input pressure by 50-100 psi depending on the bolt you're switching from and the valve in your 'gun. It isn't as easy on brittle paint as the Evolution bolt, but low pressure operation should balance that out. It has the best hard-coat of any bolt made. Despite months of use, neither of the Lightning bolt's I use show even the slightest sign of wear (after a few more months they did start to show some wear). It is also available with the same quick-pull pin system that was introduced in the Evolution. A superb bolt, but overpriced given the equivalent performance of the Shocktech Alien bolt.
- Menace bolt
As it is made entirly of delrin and is thinned down to the bare minimum required to hold this bolt together, this is probably the lightest bolt on the market. It has a HUGE insert that occludes much of the inlet, making it very restrictive to flow. As such, it is inappropriate for use with low pressure systems. If you're looking for the lightest possible bolt and run 400 psi or higher, this may be a good choice for you. By the way, it is very expensive for a plastic bolt at ~$50.
- Shocktech Alien and Superfly bolts
These bolts made by Bad Boyz Toyz are my current favorites. I have an Alien occupying the place of honor in my new Westwood Autococker. It has a three-large-hole venturi face, a slanted inlet like the Lightning, and very light delrin and aluminum construction. I've found it to be every bit as efficient as the Lightning bolt, but with smoother action (no O-rings) and a much lower price. The Superfly (pictured here) ups the ante by adding a delrin sleeve at the mid-point to protect the inside of your ´gun, an Evolution-style pull-pin, and chrome plating on the rest.
- Slingshot bolt
I hate these damn things. This traditional 6-hole venturi-faced design has a spring-loaded mid-section that allows it to stretch a bit longer when it is pulled back, allegedly to reduce blow-back. If your 'gun is properly timed, blow-back shouldn't be an issue. I think these just encourage people to mistime their 'guns. The screw which holds these together has a tendency to come out, scarring up the inside of your reciever and allowing the bolt to fall in half. I can't recommend it.