Noticed something weird with banjo (RT Classic)

[Mondoatx]

Hey guys,

Wanted to run this by everyone and see if anyone else had the same problem and if so how they addressed it.

Got this RT Classic in the mail almost 2 weeks ago... when I got it there were no fittings in the rail so when you put in the banjo and tightened it I noticed that if I turned it the right way the holes in the banjo would align with the holes in the rail that feed air to the holes in the rail.

At this point I thought to my self "it makes sense to align those holes when I can to ensure maximum air flow"...

While doing some reading while getting the beast working I noticed some people mention their guns RT more when the holes are aligned... which reinforced my earlier thought about air flow (air flow good, restriction bad).

So... I painted the field strip with nail polish to mark it so I could tighten it to align with the holes in the rail since once I put the gauge and air fitting in I could no longer see into the rail to see if it was aligned.

I got the gun working yesterday... and shot it MAYBE 100 times (not much, 100 is a generous estimate). I turned off the air and didn't look at it again until today.

Today I came and picked it up and noticed the banjo had changed position substantially (almost half a rotation)... so as I was shooting it seemed like it was turning itself.

Obviously I can't lock tite it in or do anything drastic like that... it just seemed like a lot of movement for not a lot of shots.

Anyone have this same problem? If so... how did you address it?

Does this have anything to do with shredding that middle o ring on the banjo? I am not crazy about having to tighten the banjo constantly... that middle o ring seems precarious and finicky and prone to binding (air on or off)... so I could see myself blowing a lot more of them if I am constantly having to tighten it.

Let me know your thoughts.

Thanks all.

M

[Mondoatx]

Oh... 1 more thought/piece of info...

The first time I aired up the gun it was with an 800 PSI tank... shot it maybe 40-60 times... the second time I aired up the gun I had my SHP on it (1100 Lbs)... and shot it maybe 40-50 times (probably less)... Obviously when I put the SHP on it it was totally ripping...

Just mentioning this because I am not sure which of these two sessions of shooting backed out the screw (or maybe both)...

Thanks again guys.

M

[Mondoatx]

Noticed when I was re-tightening the banjo it was hard to turn...

Took the gun apart to see what was going on...

Same thing... that middle o ring came out of its' groove up over the lip of the rail and was stuck betw the rail and the top of the banjo...

It was less severe than last time... I was able to push it back in with a tiny allen wrench and then get the bolt out without damaging the o ring...

I guess I should just buy a handful of extra banjo o rings (more than the 3 extras I have now) and keep them on hand... this seems like this will be a recurring problem.

Let me know your thoughts.

M

[Spider-TW]

Keep in mind that the threads on the banjo bolt are more coarse than the other field strip screws. I can't remember, but I'm thinking 1/4-20-ish, meaning a quarter turn is 0.0125" and that much on an on/off pin also makes a big difference. I cannot say I've ever noticed any of my other mags rate of fire being as sensitive to that screw position as an RT, so I think it may be a combination of extra air flow and effective pin length.

If you can get a thick ninja reg washer for the banjo bolt, it might let you put more tension on the banjo while keeping it aligned.

Being loose may also be a problem for the middle o-ring. With each shot, the valve pushes itself backwards. If the banjo is loose, the banjo can tilt more, exposing that front face more. The banjo on mine would bottom out in the valve very close to the designed mounting depth; don't add torque if the banjo has no where to go.

I have a little torque driver, but I never thought of testing that o-ring failure against the amount of torque on the banjo before.

***

I'm wondering how much (if any) of the middle o-ring trouble is simply the result of creep and deformation (stretch) of the banjo bolt itself. Some of the early classic automag field strip bolts had that problem. Stainless can do that.

[blackdeath1k]

If I get sloppy and lightly hand tighten my banjo it will slowly back out til I hear a seep then I tighten it correct. With my marker I find that 1/4 turn past hand snug salves most any issue I've seen. But I do have to say. In all the years I've owned my RT I have never once had a banjo bolt or Oring issue.

[Spider-TW]

So, I bought a brand new banjo bolt from the AGD store last week. It came in today. I measured it in various directions and sections. The only difference I could find from my original rail-leaker banjo was ~0.004" shorter in the new threaded section versus my old banjo (RT05813). That difference might be stretch or just tolerance. I thought it might be a burr, but I moved around to different sides and endpoints and still came up with the same difference. Not much at all.

[Mondoatx]

Hey guys,

So... not sure how many of you have been following the saga with me getting the LX in the level10 tuned... but along the way I had a TON of issues with the banjo bolt...

Basically every time I would air up the middle o ring on the banjo would pop out of its' groove get lodged between the wall of the rail and the banjo.

So... I took some advice and put a Ninja shim on the banjo... it slid all the way to the bottom... this allowed me to air up a bunch of times (too many to count) while I was trying to get the LX tuned... and I didn't have a problem... it did happen again this weekend when I took it out to play... so I am going to add another shim and see what happens...

I am thinking that with shim I added the kept the middle o ring further down and away from the edge of the rail... which is leading to it being more difficult for it to pop out of its groove...

Anyway... going to add another... will let you guys know what happened.

M