another Prod mod

[scattermaster]

So I shot my new Benjamin Marauder pistol a couple of weekends. I didn't bother to chronograph it because the catalogue power/ FPE is lower than what I want.

Over the last few days, I made my own transfer port. Factory port is .080" hole, my new one is .125.

I also opened up the firing valve exit hole to .125". I did not change the barrel port. I didn't measure it but it looks real close to the .125" already. I shimmed the hammer spring for a little more compression with a couple of model engine glow plug washers.

Tested it this morning and wow, It's a gas hog BUT I got my speed. Shooting Crosman Premier hollow points. 14.3 gr.

I don't have a way to measure the noise but it seems like it didn't really change.

1- 2950 psi- 819 fps

2. 2850 psi- error

3- 2800 psi- 842 fps

4- 2700 psi- error

5- 2650 psi- 845 fps

6- 2600 psi - error

7- 2500 psi- 839 fps

8- 2450 psi- 837 fps

9- 2400 psi- 823 fps

10- 2300 psi- 814 fps

11- 2250 psi- error

12- 2150 psi- 802 fps

13- 2050 psi- 790 fps

 

[bigheadted]

it sure is an air hog ! Especially compared to my Marauder rife but that pistol would sure be easy to pack around hunting

 

[Rj]

Have you done the bstaley oring mod yet? Should flatten that out a bit and get you a few more shots.

 

[scattermaster]

What is a "bstaley oring mod"?

It would be nice to get 2 clips through it before it drops out of the 800 fps area.

 

[Bigragu]

Don’t quote me on the O ring type, but if I remember, they are #113 Orings. Hopefully someone chimes in to verify, or just go to the marauderforums.com and there’s a sub forum for PRods. The BStaley mod is hashed over a lot on there.

you take your hammer out, and carefully slip 4 of these Orings in before the hammer goes back in. The Orings will nestle against the valve’s face. It will act as a cushion when the hammer slams against that valve stem when fired. Lightly lube the ORings with silicone grease. The Orings are pretty much the same size used on the valve, so when you find out the size, pick up extra to keep on hand for when you have to do a reseal of the gun one day. 

Dont be surprised, if after closing everything back up and firing for the first time that nothing happens. With the four Orings in front of the hammer, your hammer striker may not be out enough and unable to tap that valve stem when fired. Just carefully turn that striker out (CW turns) just enough to get the gun to finally shoot. From there, do your tweaking over the chronograph to get your desired velocity and shot count results. 

Lastly, be aware that if the gun doesn’t fire from that striker being too short, that you already have a pellet down the barrel. Take your magazine out to prevent double loading.

 

[n2stuff]

Don’t quote me on the O ring type, but if I remember, they are #113 Orings. Hopefully someone chimes in to verify, or just go to the marauderforums.com and there’s a sub forum for PRods. The BStaley mod is hashed over a lot on there.

you take your hammer out, and carefully slip 4 of these Orings in before the hammer goes back in. The Orings will nestle against the valve’s face. It will act as a cushion when the hammer slams against that valve stem when fired. Lightly lube the ORings with silicone grease. The Orings are pretty much the same size used on the valve, so when you find out the size, pick up extra to keep on hand for when you have to do a reseal of the gun one day. 

Dont be surprised, if after closing everything back up and firing for the first time that nothing happens. With the four Orings in front of the hammer, your hammer striker may not be out enough and unable to tap that valve stem when fired. Just carefully turn that striker out (CW turns) just enough to get the gun to finally shoot. From there, do your tweaking over the chronograph to get your desired velocity and shot count results. 

Lastly, be aware that if the gun doesn’t fire from that striker being too short, that you already have a pellet down the barrel. Take your magazine out to prevent double loading.

I think it is 3 o-rings but I use 2 to get the valve to open more. It doe work very well though. I think I used Hills biggest port and drilled out the valve and barrel to match. I'm shooting JSB 18.13g for 18-19FP about the same speed. I get 2 mags of shooting. Plus I'm using a Donnyfl Sumo to keep it quiet.