Quest 4B Bolt Kit
The 4B bolt kit is a heavily-enhanced firing assembly built for the FEP Quest line of markers. Our company was originally founded around this product so you can imagine it has quite a few features in store. Development and testing for the bolt kit took more than a year before it became available. From virtual simulations, stress analysis, and of course harsh field testing - we've corrected all the issues the stock Quest bolts had. We then took a step further by adding our own improvements, taking your Quest into 2011 and beyond. The 4B kit is by far the best aftermarket upgrade you can add to your Quest. Instant improvements:
The 4B kit is a drop-in upgrade that requires no modifications to the marker. It's compatible with all versions of the Quest, regardless of year or series (including PL versions) The following are included in every 4B bolt kit package:
Installation & SupportInstallation of the new kit is quick and easy. Remove your stock bolt, fully grease all o-rings on the new 4B bolt and bolt pin, then install the new kit. Additional tuning and tweaking can be done at your own choice, however many users don't even bother. The 4B bolt kit functions as seamlessly as the stock parts.
The o-rings being used are the same sizes as the stock Quest bolt parts, which also means they are all standard sizes. Click here to view an o-ring diagram. The only additional o-rings are for the bumpers. OrderingOur distributor Thirty First Outfitters is the sole distributor in the United States. We have only manufactured 100 complete kits in our initial run. We will manufacture a second batch with even more enhancements if demand requires additional kits. | 
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Technical Information
Below is a large amount of technical information about how and why the 4B bolt came into existence. The first section deals with comparisons between the 4B and other Quest bolts.
Our bolt tip is angled at 35 degrees, which cups the paintball at its highest point. This reduces the possibility of a ball breaking in the breach. Our bolt tip is also tapered to correctly seal with the Quests front breach o-ring.
Here you can see the two FEP bolt pins that are currently available on the market along with our bolt pin. As noted in the picture, our dump chamber is 1/3 smaller then the stock bolt pins. This reduces the amount of air per shot by about 33%, which obviously will increase your shots per tank. How many more shots will depend on your tank, climate and weather conditions, and of course and how your marker is set up and the paint you are shooting. We've found we get from 2-3 more pods (250-400 paintballs or about 20% more) per 68ci/4500psi tank. | |
The anti-rollback (ARB) nosecone fixes the questionable breech geometry found on Quests (and many other markers). The stock bolt allows smaller paintballs to toll back onto the bolt face; this sometimes causes balls to break in the breech, and sometimes the eyes wouldn't even sense the ball at all.
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As mentioned, the 4B bolt pin is hollow and comes in two parts. We did this for a number of reasons: firstly it reduces the overall weight of our bolt engine, reducing the overall weight of your marker. Second, it gives the dump chamber access to a larger volume of pre-firing air pressure, which ensures optimal recharge rates at higher rates of fire, plus increased efficiency too. This design eliminates the need for the loctite-sealed set screw located in the stock bolt pins. |
Results of airflow simulations utilizing Quest firing assemblies
Our initial research into the stock Quest firing assemblies required us to reverse engineer the bolt and transfer that data into 3D computer models. From there we are able to model and simulate airflow to see where the problems lie, and where room for improvement lies. Listed below are much of our research and some of our results.
We instantly discovered the factory bolts were designed with massive flow in some spots but very constricted flow in others. This meant there was quite a bit of pressure shock during each shot, mainly at the transition into the bolt face where the hole diameter shrinks to its smallest size. In practice this creates "dead spots" where pressure becomes bottled up and loses its potential energy. The act of simply smoothing out the inside diameter of the bolt does a great deal to improve this; however it makes a product that is VERY difficult to machine correctly. The factory bolts represent a much easier bolt to produce, but are very poor for controlling this pressure shock.
The second problem discovered was that the bolt porting allowed too much air pressure to be vented at once. The bolt ports exist on the largest diameter of any spool valve marker ever produced, and as stated above, pressure reaches a quick bottleneck down behind the bolt face. There's no reason for the bolt porting to be designed in this way, so we redesigned it to present a more controlled airflow.
The following graph shows the exact amount of air volume that passes through the bolt during each shot, in graphical form.
The air constriction at the bolt ports is clearly visible in the graph, and represents the bottleneck of the Quest pneumatics system. Ideally you want a linear "straight line" transition from the bottleneck point to the point of highest flow (the barrel hood). Unfortunately it's impossible to provide a completely linear transition, so the next step is to make the transition as straight as possible between the high and low points, and to smooth out the transitions using a curved structure. This is where the 4B kit's unique shape arises.
This video also shows the air turbuance that appears in the stock bolt, and the way we solved the problem by smoothing out the internal transitions of the 4B bolt assembly. |
Do you have any questions about our 4B kit? Check out our Facebook fan page and ask away. You can also feel free talking to other 4B owners and ask how this kit is working for them.