Author Topic: Simple tune for a Gen 2 .25 cal. Marauder Rifle (Read 12969 times - 1 votes)
)

HillGSA · « **on:** October 22, 2014, 04:38:33 AM »

"What is a good and simple tune for a stock Gen 2 Marauder Rifle, especially for someone that does not have access to a chronograph".

This question comes up from time to time, so since I have a stock rifle, I thought I'd post an example tune.

The test rifle:
My stock { except for the barrel band, flashlight, scope, and rings - nothing that would alter the power plant from stock } Gen 2 .25 cal. Marauder Rifle.

Specifications:
Fill pressure 3000 psi ( use an accurate gauge )
Velocity Screw ( 5/64” wrench ) = turn CW until stops, then 5.5 turns CCW ( don’t forget to remove the set screw first )
Hammer Throw ( 1/8” wrench ) = turn CCW until stops
Hammer Spring ( 1/4” wrench ) = turn CCW until stops, then 3.5 turns CW

In my rifle ( yours may vary slightly ), when shooting a 25.39 grain pellet, I get 24 shots from 810 - 840 - 810 fps ( 37 - 40 foot pounds of energy ). That is an extreme
spread in velocity of 30 fps or 3.6 %.

If you want a little more power, and with a lower E. S., but at the expense of a few less shots per fill, you can set the hammer spring preload adjustment to 4.5 turns CW.

Picture of the test rifle:

Sfttailrdr46 · « **Reply #1 on:** October 22, 2014, 10:28:08 AM »

That looks like a very good tune I will try on my Marauder and let you know how it works out

HillGSA · « **Reply #2 on:** October 22, 2014, 09:52:50 PM »

Looking forward to the results...

Alex818 · « **Reply #3 on:** February 13, 2015, 03:32:27 AM »

How did it work out for you? Did you tune for higher shot count or higher power? My goal is to achieve highest power with 16 usable shots in the Gen II .25 for hunting

Quote from: sfttailrdr46 on October 22, 2014, 10:28:08 AM

That looks like a very good tune I will try on my Marauder and let you know how it works out

wormbobskey · « **Reply #4 on:** February 13, 2015, 05:26:25 PM »

When I pump my rifle to 3000 psi on my pump it shows 3200 on the rifle gauge. I get 24 shots at 825 average fps down to 2000 psi. Point of impact does not change either. Very happy with mine so far.

GLPalinkas · « **Reply #5 on:** February 13, 2015, 06:14:45 PM »

Quote from: wormbobskey on February 13, 2015, 05:26:25 PM

When I pump my rifle to 3000 psi on my pump it shows 3200 on the rifle gauge. I get 24 shots at 825 average fps down to 2000 psi. Point of impact does not change either. Very happy with mine so far.

My gun gauge is off, similar to yours, but the ballistics sound correct and same as I get for a power tune. Now for the NIBLT tune I use 2600 fill and get a 785 average and 30 shots for about 35 FPE. .... Very happy with mine also.

wormbobskey · « **Reply #6 on:** February 14, 2015, 10:58:33 AM »

I've been told by someone in the know that crosman is going to get better gauges on future marauders. Ones that will be capable of going to 5000 psi. The rifle will still be a max 3000 psi fill but the better gauges won't be maxed out like the current 3000 psi gauges are. My gauge needle actually leans to the right with a complete fill. I never noticed it until told about it. I fill to the gauge on my pump for now and once I get my tank set up I'll use it instead of the rifles gauge. Same with my disco. Going by the pump gauge has given me a few extra shots for sure because now I'm getting a complete fill. Once I get my pellet order in I'll run the rifle over the chrono and get my best start and end fill pressure.

wormbobskey · « **Reply #7 on:** February 14, 2015, 11:01:59 AM »

Hey Tim, does the Hill barrel band still keep the barrel free floating or does it lock it down. Is the flash light bracket and barrel band all one unit? Need to mount a flash light on mine for roosting pigeons.

HillGSA · « **Reply #8 on:** February 14, 2015, 05:40:59 PM »

Quote from: wormbobskey on February 14, 2015, 11:01:59 AM

Hey Tim, does the Hill barrel band still keep the barrel free floating or does it lock it down. Is the flash light bracket and barrel band all one unit? Need to mount a flash light on mine for roosting pigeons.

There is an o-ring located in the center of the barrel band that forms a "tight fit" between the barrel band and the shroud. There are a few thousands of movement available. If the barrel band and the shroud were locked together, day to day temperature and or pressure changes could allow for the rifles poa/poi to be thrown off.

The barrel band and flashlight are 2- separate units.

I use these barrel bands on all of my marauder rifles and the poa/poi does not change from day to day.

I usually clamp the light onto the mount when it starts to get dark outside, that way if the motion detector goes off, I am ready to go

One other thing I should mention too is that the shooter can see the scopes reticle at night when the light is on. This allows for the shooter to use the same aiming methods that they would normally use during the daylight hours

Rdsail · « **Reply #9 on:** February 15, 2015, 08:45:38 AM »

This is exactly what I do when I start to tune a gun. In the .25 I don't see the point of adjusting the hammer through and velocity screw. They should stay maxed out. The only thing that should be adjusted is the hammer spring like you mentioned.

Bigtwin69 · « **Reply #10 on:** March 06, 2015, 07:50:00 PM »

Do you put anything on the threads of the velocity screw to keep it from moving or is that necessary?

HillGSA · « **Reply #11 on:** March 06, 2015, 10:20:49 PM »

Quote from: Bigtwin69 on March 06, 2015, 07:50:00 PM

Do you put anything on the threads of the velocity screw to keep it from moving or is that necessary?

I like to use a non-permanent thread locker like this one:http://hillairgun.com/archives/products/vibra-tite-vc-3

Thank you to our advertisers!

Simple tune for a Gen 2 .25 cal. Marauder Rifle