Found this while researching how to “tune my Marauder”. As he states it is not a “how to” but rather a what are the components and a starting place. Thought this might be of help to other Marauder shooters. This was written in 2009 most likely for the Gen 1 but will apply to the Gen. 2 model. He has several other posts which go into the start place if you want more information. I thought it was stated concisely and easy to understand. Hope this helps others :ShadowShot:Hello all,I am sure there will come a time when some one will ask, (like I am),
what is the factory setting for this part of the rifle, or that part?
I have not tried to call or email the factory yet on this. I am not to sure they
would give out the information but I don’t see why they wouldn’t.
I thought it would be a good idea to collect what factory settings
we have found or collected, and pool the information here for reference.I know, for example, the commonly found factory setting for the hammer stroke length,
or the “Hammer Throw” in the .22 cal rifles are maxed out at full throw length.
IE: (The 1/8 Allen screw adjustment backed counter clockwise all the way out.).
This controlls how far the hammer travels before striking the valve.This collected information is not intend to be a, “how to”, for tuning your Marauder.
It is only here for restoring your rifle to the original factory set points. You may have lost
yours during tuning or never wrote them down when you started.There are two basic areas of adjustments for the factory 2500psi Fill.
1. Velocity, which is controlled by three areas of adjustment.
(a) Hammer spring preload
(b) Hammer Stroke Length
(C) Valve Metering Screw.2. The trigger assembly.
(a) Trigger Pull
(b) Trigger Position
(c) Trigger StagesIf you would, please be very specific when you post.
I know many things can be said here of safety, how to adjust, what adjustments you have made
and so on. If you will , please post something like, “My .22 or .177 rifle came with the Hammer Stroke Length
turned 2 turns in from it max out position”. We may find that the settings are the same for both rifles. As the information comes in, I will try to keep up with it here
in this main post. Once we have completed collecting the data,
Gene might find the information of some library value.Thanks for your input and help.
ShadowShot Here is how you start:Crosman Marauder Tuning ProcedureTuning your Benjamin PCP with the use of the Hammer Spring Tension Adjuster and Hammer Stroke Adjuster
by Ray and Hans Apelles ~ The “A” Team
Caution: All testing should be done with muzzle pointed in a safe direction and into a safe backstop!!!!
Principles
Preparation:
There are many different ways a PCP may be tuned/adjusted. With the adjustable Hammer Spring Tension and
Adjustable Stroke you have virtually all you need to tune a PCP to your liking.
This Document will give you a brief introduction into adjusting and from there you will need to experiment to get the
performance you desire.
A certain amount of force is required by the hammer to open a valve to achieve a particular velocity with a given pellet.
This can be applied in a variety of ways. At one extreme the hammer can be moved a long distance (stroke) with a low
spring tension. At the other extreme the hammer can be moved a very short distance (stroke) with a very high spring
tension. And there is everything in between. Each method yields a different firing characteristic. It is up to the end user
to decide how he would like the gun adjusted to suit his needs and firing characteristic desires.
A long stroke, low spring pressure setting will give a very light cocking effort and long spring life. As the hammer opens
the valve, the pressure from the reservoir combined with the valve return spring pressure will close the valve. With a light
spring pressure the hammer is likely to be thrown back far enough (and off of the valve stem) that the hammer spring then
gets re-tensioned and the hammer gets thrown forward to hit the valve stem again and expel more air. This can be heard
and sounds as though the gun is burping out air for as many as 3 or 4 burps per shot.
A short stroke, high spring pressure setting will yield a heavy cocking effort and possibly shorter hammer spring life. As
the hammer opens the valve, the pressure from the reservoir combined with the valve return spring pressure will close the
valve. With a heavy hammer spring tension the hammer can’t get thrown back so far (or possibly not even off the valve
stem) as to tighten up the hammer spring and throw the hammer back onto the valve to burp out more air. There is the
small possibility that the valve may also close slower, allowing more air to escape, because of the added hammer spring
tension keeping the hammer against the valve. This method of tuning usually yields a shorter sharper crack at discharge.
This method yields little to no Hammer Bounce.
The best balance between the long stroke low spring tension and the short stroke high spring tension is what is desired.
The following guide will help you achieve a setting that will give you the desired velocity. It will be up to the user to
achieve the balance they desire for an optimal setting. An optimal setting will give the highest efficiency yielding little to
no hammer bounce, reasonable cocking effort and good shot consistency.
It would be a good learning experience to try each method so as to learn the characteristics of each in your particular gun.
Start with the long stroke low hammer tension (which is very similar to the factory setting) and then try the short stroke
high hammer tension method. After learning each you can then find a balance between the two. When finding the
balance, if you can hear any air burp then you should adjust more to a shorter stroke higher hammer tension. You are
looking for that fine balance which can only come from experience. At the end of this document you will find a method for
determining charge pressure and shot count. It is advisable to do each for the 2 different methods so you can see the
difference in shot count and velocity curve which will give you an idea of the efficiency you have achieved in each.
After finding your setting for each method, you can determine that setting by inserting the adjustment wrenches and
counting how many turns to get back to the end stops. An example would be 7 turns in hammer spring, 5 turns in stroke
yields 850 fps with xyz pellet with a 2000 psi charge for 25 shots. Using this method you can always get back to a
particular setting while you are trying different settings.
A) Hammer Stroke Adjustment (HSA): With the gun assembled, adjust the hammer stroke to the longest stroke position.
This is done by inserting the Hammer Stroke Adjustment (HSA) allen wrench through the Hammer Spring Tension
Adjuster (HSTA), through the spring, into the hammer and catching the Hammer Striker. Then turn counter clockwise until
the Striker is to the fully retracted position. This is the start position for your adjustments.
B) Hammer Spring Tension Adjustment (HSTA): With the gun assembled, adjust the Hammer Spring Tension to the least
tension position. This is done by inserting the Hammer Spring Tension Adjustment (HTA) allen wrench into the end plug
and catching the HSTA and turning counter clockwise until the Hammer Spring Tensioner is to the fully retracted position.
This is the start position for your adjustments.
Revised 6/1/2009
C) If it is possible, make an identical replacement of the transfer port but change the ID to .110″ or smaller. It is rare that a
PCP needs a transfer port larger than .110 to achieve 20 ftlbs. If you are trying to significantly reduce the power of (as an
example) the Discovery then you may go smaller yet. As an example, one that we tuned used a .105″ transfer port to get
just below 20 ftlbs. The transfer port in the Discovery is large because it is designed to work with CO2 as well and needs
the larger size for the lower pressure CO2 gas. A Transfer Port that is large enough to give you the velocity you desire
but no more will give you a flatter velocity curve. It is not mandatory that you replace the transfer port but it is beneficial.
In the case of the Marauder, turn the transfer port adjustment all the way in (clockwise) and then turn it out 4 revolutions
(counter clockwise). This is the starting point for the adjustable transfer port which is now all the way open.
1) Set up a chronograph station with the assembled gun on sand bags in front of the chronograph so your readings will be
consistent. The Muzzle should be at least 18 inches from the first sensor to prevent incorrect readings.
2) Have initial adjustments of the PCP set to A, B and C above.
Note: you will initially be tuning for a particular charge range so you will need to charge the gun to the same pressure
each time and every 5 shots or so to maintain pressure during setting. Changes in charge pressure will give you changes
in readings that will confuse the issue. Once the settings are complete then you will determine correct charge pressure
and number of shots for that pressure.
3) Charge gun to a pressure that will be a little above the middle of your desired charge range. Example: If you are
looking to charge to 2000 psi and shoot to 1000 psi then charge to 1600 psi for testing.
4) Turn in (clockwise) the hammer tension until you feel tension on the hammer spring and then turn 1 more revolution in.
5) Chronograph a shot to see where your velocity is.
6) Increase hammer tension 1 turn.
7) Repeat 5 and 6 until your desired velocity is reached.
8 Shorten your hammer stroke 1/2 turn.
9) Chronograph a shot to see where your velocity is.
10) If your velocity stayed the same go to 8. If your velocity decreased go to 6.
11) Keep making adjustments (remember to charge every 5 shots) and chronographing until you are satisfied with the feel
of the shot cycle. This is learned through experience and can not be adequately explained.
4) Cock Hammer.
5) Turn in (clockwise) the hammer tension until you reach full coil bind and can not turn the hammer tension in any further
(gun may fire during this adjustment). Fire gun. Cock the hammer again. If it will not cock then turn hammer tension out
1/2 turn. Cock gun again. Repeat until gun will cock reliably.
6) Turn hammer tension out 2 to 3 turns.
7) Chronograph a shot to see where your velocity is.
8 Shorten your hammer stroke 1/2 turn.
9) Repeat 7 and 8 until your desired velocity is reached.
You may see that as the stroke is decreased the velocity will actually increase. This is a common phenomenon as a more
efficient setting is reached.
Adjustments:
Method 1
Method 2
Revised 6/1/2009
10) Keep making adjustments (remember to charge every 5 shots) and chronographing until you are satisfied with the feel
of the shot cycle and velocity. This is learned through experience and can not be adequately explained.
If your PCP has an Adjustable Transfer Port (as does the Marauder) then you can fine tune the velocity.
1) Turn the adjustment screw in ¼ turn at a time and chronograph a shot.
2) Make another ¼ turn adjustment and chronograph another shot.
Repeat the process until you reach your desired velocity.
During this process you may notice that the PCP gets quieter and blows less air but the velocity doesn’t change much.
This is common as you are achieving a more efficient setting. Your shot count will increase as well.
Another benefit of a PCP with an adjustable transfer port is that you can dramatically flatten a velocity curve by restricting
the transfer port and increasing the energy used to open the valve stem.
You will increase the usable charge pressure band and increase shot count in the process.
You will have to experiment with the settings to achieve this type of balance.
It will not be explained in detail here. It is mentioned here so you can strive to achieve such a balance as you are gaining
experience with the other adjustments.
Fine Tuning Velocity with an Adjustable Transfer Port
Re
