Benjamin Newb Attempts Minor Modifications and Fixes to Benjamin Bulldog .357

[Ezana4CE]

As some of you know I’m a newbie to the airgun world with the exception of the Crossman pump-action bb guns that many of us grew up with. This Bulldog is my first PCP. I’ve been watching videos and reading about modifications and tune-up options from Veradium and Pitbull Airguns. I saw how a depinger could be very useful with the rifle. I’ve also noticed that my groupings pull to the side (the right mostly) when shooting and an occasional flyer. So I figured installing additional barrel supports wouldn’t hurt (I also recently learned about lapping scope rings so that’s next on my agenda). I’d purchased a depinger and some barrel supports last month and after watching other members work on their guns, I worked up my courage to give it a shot today. A few of you have suggested or hinted at building some things for my rifle as opposed to buying them. Truth is, I’m about as handy as toddler. I’m hoping that my interest in this hobby motivates me to learn how do more of my own maintenance on my own gear. I’ll post a couple pics, but I’m still working on finishing this up. If something looks wrong or like a bad idea your input is welcome.


The magnet on top of the owner’s manual (on the left) definitely helps remove a couple of the more recessed screws. In a video I watched the poster noted that some screws are longer than others on the Bulldog so I drew a crude diagram to note where which screws came from for reassembly. Something that wasn’t too clear to me was which direction to install the plenum spacer (I think that’s what it’s called) in the depinger kit. The black tube in the second pic that’s open on one end and has a smaller circular opening on the other end that goes in the air reservoir on top of the plastic plug. Anyhow that’s in and I put the reservoir back on before putting it back in I put a layer of PTFE Thread Tape rated for gas pipes around the threads. I have a gradual leak either coming from the reservoir threads or the fill port threads. I just figured it wouldn’t hurt to place PTFE tape around the threads of both areas to see if it stops the leak. Still working on it. Anyone think it’s a bad idea to put PTFE tape on the pressure relief screw? Do you think a single layer would stop the air from escaping after backing the screw off a turn or two in attempt to depressurize the reservoir?

 

[Ezana4CE]

Anyone know how to remove the barrel spacer in the third picture?

 

[Ezana4CE]

Looks like went 1-2 tonight. Got the depinger installed relatively easy. The barrel supports turned into an utter disaster. Either I did everything wrong or they’re too small. I had to bang these things down every centimeter of the barrel. I used a crescent wrench and a ball peen hammer. I adjusted the wrench around the barrel and situated the thickest part of the wrench over a sturdy part the barrel supports. Then I began to tap and hammer away at the wrench slowly working the supports down. This can’t be the way to do this. I didn’t find any videos on installing these things. I bought these supports from Pitbull Airguns. While searching for a video on installing these I saw people selling supports that looked slightly different. If I have to cut these off, I may try some others that I saw. As you can see in the pic, they are obviously out of alignment. I can’t put the barrel back on like this. I didn’t figured how to rotate them. The two that are bunched up I tried banging them down together but hadn’t thought of how I’d separate them to space them once I got them in the area I wanted. Tomorrow’s task will be to either straighten them out so that they align or cut them off. That wasn’t fun. Hopefully I didn’t damage the barrel beyond some small cosmetic looking nicks

in the paint. 

 

[ApexPredator]

 

[Guest]

Eeeeeek. Good luck.

 

[RobR]

I installed both the barrel supports and depinger from pit bull in my bulldog several years ago. Both parts were received straight from the 3D printer and required finish work to be installed. Meaning I had to spend quite a bit of time sanding the imperfections in order for them to fit correctly. 


All sealing is done with o rings without any need for thread tape. It is likely the cause of your leaks. 

 

[Ezana4CE]

I installed both the barrel supports and depinger from pit bull in my bulldog several years ago. Both parts were received straight from the 3D printer and required finish work to be installed. Meaning I had to spend quite a bit of time sanding the imperfections in order for them to fit correctly. 


All sealing is done with o rings without any need for thread tape. It is likely the cause of your leaks.

Lol. Would’ve been nice if I’d thought of sanding before the banging commenced. Worst case scenario, I’ll have to locate and install a new barrel. I’ve had a slow leak since I’ve had it. I’m just experimenting trying stop it. Until I took it apart to see the o rings it was difficult to envision them by viewing diagrams. The pressure relief screw may have had some loctite or something on it because there was some black plastic looking material on the threads. I’ve read about spraying the areas with soapy water to look for the leak. I’ll try that next to see if it reveals anything substantial. 

 

[Ezana4CE]

I know right? I’m curious to see how it shoots once I put it back together. 

 

[Ezana4CE]

Eeeeeek. Good luck.

Haha. Right. Quite a bind I’ve created here. Moving forward at least you all can see that if I ask for help I probably genuinely need it regardless of how dumb or simple my question may sound. 

 

[Ezana4CE]

Ok removed the barrel supports pretty fast. I used the same crescent wrench to take them off. I ditched the ball peen for a rubber mallet. Removal of all four took about 5-7 minutes.

I now have nicks and scratches to the outside of the barrel. Any suggestions on paint or a coating to apply in order to protect these blemishes from turning into rust spots?

Now I will try sanding the inside of the supports to widen the diameter for an easier fit. Thanks @robr for the suggestion. Also there was light coating of some sort of oil or grease on the barrel that the manufacturer applied. It blackened my gloves. Any idea what it was? 

 

[RobR]

I do recall having seen thread sealant tape used on male foster fittings and it was black. That was likely a tapered pipe thread I’d assume. I’m still learning as I go also. Your leak might very well be coming from the one way valve in your fill port foster fitting. I do remember having to have my gun cocked in order to fill it. Gave myself a scare when it wouldn’t build pressure after I got it back together 

 

[Ezana4CE]

Per @robr’s suggestion I have sanded one of the supports and replaced it on the barrel by hand. I can rotate it to situate it where I want. It’s not too loose, not too tight. I took some cheap 100 grain sandpaper from Harbor Freight (It says 100 on the back of the paper) and a sharpie permanent marker. Tore a couple strips of paper and wrapped it around the sharpie. Next inserted the wrapped marker through the center of the Pitbull Airgun 3D printed barrel support. I used rotating and back-and-forth motions to sand the inner surface. Took a maximum of about 11 minutes on one support. I sanded, used a twisted dry paper towel to remove plastic and sand particles that come off after blowing the dust away with my mouth. Finally I tried to fit the newly sanded support onto the barrel. After the first attempt it fit snugly on to the end of the barrel where the factory barrel support fitting is usually situated. There is a flat surface on top of the end of the barrel to accommodate that fitting. The 3D barrel support wouldn’t move beyond the flat surface so I removed it and sanded some more. The result is the second picture. Fits great by hand and no great force is needed to install it now. 

 

[Ezana4CE]

Got them all sanded. I sanded one a tad too much and it fit loosely. Placed two small strips of electrical tape on the inner surface of the barrel support to provide more contact with the barrel. When replacing that support onto the barrel one piece of tape was pushed off. The tape does add a little more surface area to make it fit more securely. Mind you this is all new to me and I’m just trying solutions as you all suggest them or as they come to me. Hopefully my follies will save some other newbs from future headaches. 

 

[bthurman]

Ezana4CE, you should not use sealant tape on anything except the pressure gauge threads, and I would suggest using Oatley gray tape not the blue, it is only rated to 2600psi. If your rear tank cap is leaking replace the cap oiring and the 2 small ones on the end of the cap were it goes into the receiver body against valve casing. If you would like some barrel supports that have been machined to fit that barrel and are factory let me know I will be happy to give you a couple to make sure the barrel alignment is centered. For the barrel scratches get a can of Krylon Camo black and a couple quick shots will protect the bare spots on your barrel.

 

[Ezana4CE]

@bthurman Thank you. If I remember correctly you’re with Veradium Air. I have to break the rifle back down to remove the tape.This ought to be fun. Since you dropped in I have another question for you. When I disassembled the Bulldog I didn’t really pay attention to the distance between then the factory barrel spacer and the shroud cap. When I reassembled it I saw a noticeable gap between the two parts. I obviously couldn’t photograph the gap between the parts with the shroud cap on, but does this pic look right? It appears to me that there’s a 1.5” - 2” gap between the end of the barrel spacer and the opening of shroud cover. Should they not be flush with one another? Seems kinda strange to have pellets/bullets spanning a gap like this.

 

[bthurman]

Ezana4CE. , yes with Veradium Air, The gap you are refering to allows for some moderate air stripping, this is a factory design. If you need o ring set let me know, and you can contact me at veradium or PM and I will send over the supports for you.

 

[Ezana4CE]

@bthurman Thank you for your input. The only spare o rings that I have are the size of the breach o ring. If I need an o ring set or find my current set of barrel supports inadequate I will definitely contact you.

 

[Ezana4CE]

This stripped out hex head screw had been giving me hell. First I tried to JB weld an Allen wrench to it in order to bond it in there and unscrew it. That didn’t work well at all. 

Next I took @bthurman’s advice and tried hand filing a slot in the screw. Not much luck there, I couldn’t make the slot quite deep enough.

I used files from this set 

Finally I bought a Dremel tool and a diamond tipped carving/engraving head and proceeded to make a deeper slot. Failed there. So my last attempt was to cut a slot perpendicular to the first creating a cross Phillips head type of cut.

That didn’t work well with a Phillips screwdriver and I didn’t want to strip the head out to the point where it would have to be cut off and drilled out. My last resort was to use a flathead screwdriver in the second slot I cut. Here’s where I found success with a vise and a good amount of downward pressure.

Lesson learned. Don’t use too much torque when reassembling a rifle. Now I see why the manufacturer used Locktite. As you may be able to see I marred the shroud around the screw in the process, but the important thing is that I got it out. Some marring occurred when I used some small hobby hand files and some came from the Dremel. I ended up partially flattening and bending a beer bottle cap to place between areas of the shroud and the Dremel tip to prevent further marring. Now the rifle is all broken down and I’m removing the Teflon tape that I wasn’t sure about using in attempt to stop an air leak when I last broke the rifle down. 

 

[Ezana4CE]

Reassembled. All that’s left is to fill ‘er up and mount a scope. 

Found a replacement screw at Lowe’s for the one that got stuck. I looked up the part number from the assembly schematic and bought a matching screw using the listed size and number. It’s silver, most likely aluminum, but it works. 

Hopefully I’ll take her out for some target practice tomorrow. I still don’t think I found the leak because I haven’t torn down the receiver assembly to access o-rings in it. Eventually I’ll attempt to restore the marred surfaces. I’ve learned some things about this rifle in this process. I’m definitely comfortable breaking her down and reassembling her with the exception of the receiver. I still need to learn the parts of the receiver assembly which looks like I’ll need to use a punch set to remove several pins. 

 

[Ezana4CE]

I attempted to fill her with air yesterday and I noticed that she was leaking air faster than before from around the fill port nipple. I think I either didn’t tighten something correctly or the o-ring is gone. Mind you I’ve had a slow leak since I received the rifle new. Because I was only able to remove the fill port nipple with a crescent wrench I thought perhaps I needed to disassemble the receiver to access the fill nipple adapter which has an o-ring in the end, but it lacks a hexohonal surface to grip with a wrench from what I recall. So after getting some sleep and Brian questioning why I think I need to take the receiver apart. I’m going to have another look at the fillport assembly to see about checking the o-ring(s) without taking the receiver apart.