All Springer/NP/PCP Air Gun Discussion General > PCP/CO2/HPA Air Gun Gates "The Darkside"

Need more velocity from my 22 Cal Benjamin Marauder with MDS Hammer and TSS

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Fred J:
I recently converted my .177 Cal Benjamin Marauder (with a MDS hammer and Twin Spring System) to a 22 Cal.

The problem I ran into is that I can only get 770 fps with 18.13gr JSB pellets when I use the MDS hammer (no provision for the stock striker) and the TSS (with a 12 pound spring) when I am maintaining about 0.040" free flight, and the meter valve opened 6 turns. I am getting 60 good shots with less than 2% ES, but I would like to get my velocity up to 850 fps with the 18 gr pellets.

I have no problem achieving 850 - 860 fps if I replace the TSS with the stock hammer spring turned in 4.5 turns), and the meter valve turned out 3 turns. I am getting 32 shots with an ES of less than 2%. I am using the MDS hammer in this tune. I thought of putting the TSS back in the rifle, and re-installing the stock hammer, but the stock hammer tends to bind during cocking.

Is there something I am doing wrong with the TSS? I am not real mechanically inclined, so I don't want to drill out the transfer port or replace valve components.

Thank you!

 Two things you can try one is putting some extra weight in the back of the hammer spring bore or open up the transfer port some.

Fred J:
Thank you for your advice. I have a question for you: I recently ordered a new mds hammer from JSAR. I was surprise to see that I received a 'Buffered' hammer (see attached picture). I didn't send it back, because it looks real interesting. I have seen some pictures posted on GTA, and some of the guys think it is a Raptor hammer. I can't use this hammer with my TSS, since there is considerable pre-load on the TSS springs. Could I use this hammer in my gen II marauder? If so, how would I tune it? It look like one could adjust the size of the buffer by adjusting the space between the recessed striker and the end of the hammer.

I tried the buffer hammer out with the striker fully recessed with my stock hammer spring. Other than some vibration during the shot cyle, it seemed to shoot OK, except I was only able to achieve 720 fps with JSB 18.13gr pellets before the stock hammer spring became coiled-bound (3 turns in for the hammer tension). So I just put the buffer hammer away and used my old mds hammer with my stock spring, per my previous post.

I have a stock hammer spring, a 10 lb spring and a 12 pound spring. Any suggestions? No instructions came with the buffered hammer.

Thank you for your help!

I would be willing to experiment with this buffered hammer, but I have no experience with adjusting a recessed striker.

bear air:
Are you still using the 22 transfer port? If so you could step it up to the 25 cal one. It's a direct swap with the 22. I believe the 22 sits at .125 and the stock 25 is at .140. That will allow more air flow which will increase velocity but lower shot count. If your gun will shoot the 15.89gr pellets accurately that could be another option too.

Fred J:
Thank you for your advice, Chris. I will try the 25 Cal transfer port. I have tried the 15.89gr pellets in my Marauder: They are accurate, but they don't buck the wind like the 18.13gr pellets.


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