P-rod power mod

[Darinjfry]

Does anyone out there work on Benjamin marauder pistols? I chronyed my p-rod and although I thought I had it maxed out on power it is only shooting 560-570 fps. Would like to get 700 fps or if anyone does custom work get a double air tube and get 800 fps. Working in it myself is not really an option as I'm not very handy at that kind of thing so I'd have to send it to someone

[Norm_m]

700 FPS with a PRod is pretty easy to get. Just try drilling the transfer port out to .110

Norm

[CatbirdSHV]

Rocker1 does lots of them.  Mine is now shooting 18 fpe and it started at 13-14.

[moorepower]

A .110 tp and a .041 or .047 spring and 3 3/4" square orings and I have 18 shots 700-720-700. Very little pumping

[Skinard88]

3 3\4" square orings?   I haven't heard of this.

[beejwest]

Search for "b-staley mod" and you'll find what you need.  I'm at 720-740-720 for 24 shots. 

[Wayne52]

When I got my Prod the adjustments weren't even close to what one would expect.  Actually the trigger itself was set too light which made it do some odd things, I could pull through first and second stage and it wouldn't do anything until I released the trigger, then it would fire.  This was the first thing I adjusted and once I adjusted it, it has a very nice first and second stage now(very low and smooth pull).  I then checked how the hammer tension and throw were, well the throw adjustment was turned all the way clockwise(least amount of throw) and the tension of the hammer spring was adjusted almost wide open.  I pretty much left the hammer tension the same and have the hammer throw set to about 3 1/2 turns counterclockwise.  I now get well into the 700fps range with Crosman 14.3's

[rustysocket]

I have a brand new unmolested prod that arrived a few days ago.  Im in the process of figuring out what pellets it likes stock before i start to tinker with it.

What is the best way to document the stock settings so i can get it back to factory?

[Darinjfry]

There is a YouTube video that explains the different spring and hammer tension adjustments pretty well. Just make sure you write down how many turns you make from where you syarted

[FuzzyGrub]

If you are using 14-15g pellets, the stock Prod should go to 650fps.  I suspect something is wrong if it can't hit 600 with max preload and min throw on 3K fill.

Once that is figured out, I do recommend the Bstalley o-ring buffer mentioned above, with 0.110" TP and heavier hammer spring http://www.mcmaster.com/#9434k65/=14c16i3  You should get 24 shots @ 16fpe or 16 shots @ 20fpe with it, or anywhere between.  Much more than 20fpe, you get into valve mods.  It is also limited by its short hammer throw (1/2"), small air res, and short barrel, which means allot of mods to get above 30fpe and have a decent shot count.

FWIW: I do not recommend going to a 1.75" spring with larger wire than stock.  It will go into coil bind before you can get to max preload.  Some use the disco spring which is same wire dia and spring dia, but is 1.75" vs prod of 1.5".    I prefer the MC spring that I listed above, though.

[beejwest]

^^^^^^this^^^^

Above 20 FPE you get highly diminished returns.   17 FPE was bread and butter zone.  Mine shoots FTT 14.66 with the 5.54 head like a champ.

[Darinjfry]

Yeah something isn't quite right power wise (accuracy wise my p-rod is a dream). I wonder if spring is just old and loosing tension? I've contacted rocker1 and am considering a power mod, but may also get a double tube mod

[FuzzyGrub]

I'm sure David will fix you right up. 

While it could be the spring, there are a number of other things that may not be as easy of a fix.   If the airtube or valve is not in spec, you may be getting a partial blocking of the TP.   Usually, this not enough of an issue with the standard TP, but can become an issue when going to larger.   

I have seen under performing guns start to get all sorts of power mods, and still have issues.  Its best to find out what that is prior to mods, especially if it happens to still be on warrantee.

[Darinjfry]

I doubt it's still under warranty. Bout it second hand off someone. Was hoping David would check it out or hopefully fix the problem when he modded it

[FuzzyGrub]

Was hoping David would check it out or hopefully fix the problem when he modded it

As long as you let him know that is what you want.  I have worked with David on a number of mod parts.  He will make sure you are happy with his work.