Thought someone would've said something by now. Not sure if you're still going to see this, but here goes my take:
By the time you're done lowering the "kickl" on your A-5 to the level of other poppet markers, like say a SC'd marq, you will have spent at least twice what the other marker was when it was new ( so, probably about $2000+). If you're in it for performance, get a new marker; if you're in it for the tinkering... keep reading.
Let's start with the basics:
Recoil is energy transferred to the user, there are 2 main components to this in a paintball marker: the energy of the ball being shot and the energy of the mechanical components moving inside the marker. Now, the energy required to shoot a ball at 280+ fps will be the same and have roughly the same effect regardless of the means used to achieve this since Ke=(1/2)mv^2.
That said, there are several ways of getting the ball (m) to 280+ FPS (v). In order for the ball to reach v, there needs to be a force (F) applied to it to get it to move, which will cause it to accelerate (a) until it reaches v. The magnitude of the applied force (F) is equal to the ball's mass (m), multiplied by the rate of acceleration (a); so, the less acceleration, the smaller F's magnitude needs to be. Remember that law of motion that states that for every action there's an equal and opposite reaction? that means that F experienced by the ball is the same magnitude as the one experienced by the shooter in the opposite direction (against your shoulder, ideally).
You with me so far?
So, we've established that less a will get you to use a lower F which is felt by the shooter. How do you use a lower F? Well, you can use a lower operating pressure (P) since P is the measure of force applied to a certain area (A) P=F/A, the sectional area (cross cut area) will remain constant('ish, depending on how consistent the paint you're using is) at about pi*(0.68/2)^2 inches, so the one thing we can change to affect the force is the pressure applied to said area (PA=F). Using lower pressure means that you will need to use a higher volume (V) in the valve chamber to contain the same amount of air (n), since nP1/V1=nP2/V2 and the air contained in a lower pressure vessel will have slightly less energy stored than the same amount in a higher pressure vessel.
Are you still following?
So, we've established that lower pressure means less force felt by the shooter because the ball accelerates for a longer time, but it requires a larger valve chamber. Another thing it requires is a longer control bore. Since F takes longer to accelerate the ball to v, the ball needs more space (L) to move while accelerating to v (think of it as 2 cars that top out at 150 MPH, but one's modded for 1/4 mile drag racing; they'll both get to 150, but it'll take the drag racer a lot less road to do it). In order for the L required to accelerate to not be too long, the ball needs a good seal in the control bore (going back to the car comparison, the unmoded car fitted with racing tires is going to grip the road and accelerate better than the same car with economy tires that slip more easily); since paint can deform slightly before breaking due to its nature (gelatin shell), I would advise underboring to make the best seal possible in the control bore, ensuring air doesn't slip by the ball and so that the control bore doesn't need to be 12" long or more.
Ok, so that more or less takes care of the ball side of things, so to recap:
- Low operating pressure
- Larger valve chamber
- Long control bore
Now onto the internal side of things: Since the hammer is affected by the valve chamber air being bled from the firing cycle, the same as applies to the ball applies to it: Using a low P (LP) will make it move slower, lowering the impact on the back cap (even with the buffer o-ring). Lowering the mass of the hammer will also lower the energy transferred to the shooter Ke=(1/2)mv^2, but it will also mean that the hammer will need a harder spring to open the valve properly Se=(1/2)kx^2, since it still requires the same amount of energy as before the lightened hammer was installed. Thankfully, LP goes hand in hand with spring changes to a lighter spring rate, until P is too low to provide enough acceleration inside the power tube and you need to either get a longer power tube or change the way you open the valve. Enter the e-bolt system, this makes your hammer operate with a board, LPR, solenoid valve and a pneumatic ram which are independent of the pressure in the valve sleeve. Basically it turns your tippmann into a crude gen1 marq with the bolt linked to the ram out the side in stead of the center line.
In order for you to get the lowest P possible, you'll need to smooth out and remove obstructions form the air's flow path, so unscrew the adjustment all the way out and use the highest flowing parts you can find.
All in all, I'd say you'll want:
- LP kit
- E-bolt with a QEV on the front sleeve port (probably need to make one, as they're as scarce as hen's teeth)
- Valve spring kit (if there even is one)
- Non-adjustable power tube
- Bolt with an inner seal
- Underbored barrel with a long control bore