My p-rod isn't a complete dudd

[AntlergeekAdam]

First off, hello. My name is Adam and I'm from Michigan. I've been around guns my whole life and I'm actually a full-time handgun shooting instructor. I've been searching this website for a few weeks trying to gain information on a recent purchase. I ended up buying a crosman marauder pistol from PA. One of the biggest complaints I could find about the gun was being pellet picky. Well I've shot numerous different types of pellets through her and the only ones that seem to somewhat group are some RWS super domes. Crosman hollowpoints and CPD gave shotgun patterns. I have some ftt in 5.53 and 5.55 on order because thats a very common pellet used in the p-rod. I've done the b-staley tune as well as drilled the TP out with a 7/64 drill bit. I tapped the hammer and installed a grub screw to hold everything in place.
When I ordered the gun I did the package deal and it came with the Benjamin hand pump. I take my time doing deliberate strokes all the way up and all the way down. No complaints with the pump so far. But just recently I'll pump the gun to around 2900 psi and both gun and pump gauges will be reading the same, but when I bleed the pressure screw I watch the psi on the gun instantly drop 400 to 500 psi. Can someone point me into the right direction what is going on??? Other than not hitting the barrel lottery I really do enjoy this gun

[larspawn]

Welcome Adam! 
 
On bleed down do you bleed fast or slow?  If you go slow it is possible that the valve on the pistol won't close fast and you will lose some pressure.

My Prod carbine shoots Crossman Premier HP from Wallyworld and Webley Acupels well enough that I haven't even tried anything else.

Lake Orion!  You aren't far from my office.  Auburn Hills!  But live in Plymouth.  Welcome to the GTA!

[AntlergeekAdam]

Small world. I work in Clarkson.
When I bleed the pump I try to do it as fast as possible.
The ftt's should be here Monday and I've heard good things about them in the P-rod. There was no consistency with any of the crosman pellets

[Ribbonstone]

Have had a few troubles with pellet-picky/accuracy with my P-Rod.  One of the first year, and I had hoped that the newer barrels had gotten better.

I’d do two things first:
1. clean the barrel.
2. test without the magazine (single loading).


First problem turned out to be a magazine.  Was much worse accuracy with the magazine than when single loaded.  Replacement mag didn’t show the problem. Whatever that first mags problem was, couldn’t  SEE any difference by eyeball . I didn’t bother to trace down the issue and just junked the offending mag.

Barrel was this ones main issue.  Even an eyeball exam showed rough and very shallow rifling.   Did all I could for that barrel, and did manage to find a pellet it shot reasonably well (H&N F.T.T.).  Still needed to clean the barrel every 40-50 shots or accuracy would go to pot, but at least it shot well between cleanings.

Had 3 choices back then:

1. Live with it, as it shot well enough for most uses.
2. Enter the Crosman barrel lottery and order a new factory barrel.
3. Get a replacement  aftermarket barrel.

[AntlergeekAdam]

I did single shot hand loading an groups didn't improve... This one is definitely barrel. I did find that one mag shot worse than the other. Barrel had been cleaned twice and still no improvement.

I'm still trying to figure out why the pressure is dropping when I bleed the pump

I called crosman and they are sending me a different barrel. The guns brand new and they said that the warranty would be void if I changed the barrel. I work on my own stuff and figured it would be better to do it myself than package the whole gun and send it in. It's just a shame that their barrel QC couldn't be better. Here a gun manufacturer that sells guns and ammo, but the gun absolutely hates the ammo that they make??? Makes no sense.

[garczar6]

All i shoot in mine is 5.53FTT's. Nuff said as far as mine goes. You can get a barrel from Gaska that's specifically made for JSB's. I've got one but am not installing 'til OE barrel gives up.

[chuckinohio]

  You may have a small piece of debris lodged under the seat where the valve seals in the fill nipple, or the seal may be nicked or damaged. it may also be that the spring, if equipped, is hanging up internally.
  Look partway down this page for an idea of what may be happening- http://tko22.com/
  You could try to disassemble when the gun is depressurized and examine it under magnification for any problem.

[AntlergeekAdam]

Thanks for the replies. I'm just waiting on the ftt's. If they shoot good out of the barrel I'll just buy a big supply and be good to go. I'll also be taking a closer look at the fill nipple to see is something is going wrong there. I have the gun here at work with me. It's nice being able to bring guns to work, after all it is a gun range. Thanks Again

[AntlergeekAdam]

 Do I have to disassemble the fill nipple to "Spritz" with silicone that he is talking about?? or can I ease some silicone in the fill cap and hope that it works its way in when I pump??

[Ribbonstone]

Would degass...then take the fill nipple off...then take the fill nipple apart..clean it and lube the internal o-ring with silicon grease.


They are simple. Just an o-ringed shaft that rifes in the venter of the fill nipple.  That -o-ring seals the the inside of the fill nipple when the pressure inside the gun is higher pressure than the air pressure outside the gun.  BUT the o-ring seat can get dirty/corroded and not give a smooth surface foe that o-ring to seal to.   

So degass...take the nipple off...take the central part of the fill nipple out...and be sure that (1) there is no "gunk" keeping it from sealing and (2) the seat for the 0-ring isn't rough corroded .

[AntlergeekAdam]

Sounds easy enough. Thank you

[AntlergeekAdam]

While I am in there I'll clean up the inside of the air tube. I'm sure there is a little bit of moisture...do you guys lightly lube the cylinder wall with anything to prevent corrosion??? I know that you shouldn't use petroleum base lubes but do you guys use silicone???

[RatRacer]

I use 100% silicone plumbers grease from Ace.

[AntlergeekAdam]

I use 100% silicone plumbers grease from Ace.

perfect, that's what I have

[AntlergeekAdam]

So last night I degassed the gun and removed the complete end cap with the foster fitting. I then removed the male foster fitting from the end cap. I pulled out the little valve stem that has the little white oring on it and everything looks fine. I inspected it closely and reassembled it with a light coating of silicone. I connected the hand pump and began charging the cylinder. When I got to 2900 psi I watched the guns gauge. When I bled the pressure screw it instantly dropped to 2400 psi. This morning the gun is still at 2400 psi. I'm wondering if I should call crosman and get a new foster end cap?? Or if there is something else that I'm missing??

[RatRacer]

I would, especially since you're hand pumping, to have that effort go to waste.

[AntlergeekAdam]

I would, especially since you're hand pumping, to have that effort go to waste.

Just got off the phone with crosman. They are sending me a new male foster fitting. I can't see why anything else would be the problem

[AntlergeekAdam]

The new barrel was waiting for me when I got back from vacation. Installed the new barrel and grabbed my tin of crosman domes. 25 yards. One ragged hole with 24 shots that you could cover with a quarter, and that was just resting on the back of the tailgate of the truck. I got lucky and won the barrel lottery the first try. Now I don't have to order special pellets. I'm a happy camper

[nomobux]

  Could someone link me to the Gaska barrel. thanx

[RatRacer]

  Could someone link me to the Gaska barrel. thanx

http://www.marmotmilitia.com/hammer-forged-barrels.html