Hop up bucking lubrication...How much?

[cjfield1129]

I think I may have found the culprit for some FPS loss and wanted some input. I installed a new Guarder clear bucking recently. During installation, I sprayed 100% silicon spray on the barrel, put the bucking on the barrel, sprayed some silicon on the bucking, put the bucking w/barrel into the hop up chamber, and reassembled back into the gun. When test firing, accuracy was the same as before the change but the FPS dropped quite a bit. I do have a RH65 bucking on order but want to know if I should not use the spray silicon. I have posted in other forums, but I wanted supplemental advise as different techs moderate different sites. Thanks for any help.

[CDN_Stalker]

Not much, Best to put a drop or two in the loading tube, fire it off a bit to get excess out, etc. and you should be good to go for a few thousand shots. I'd say the spray is overkill. Can't see how your fps would drop though, in my mind a slick hop up rubber will increase fps over a sticky one (less friction). Try taking the rubber out and reinstalling, sounds like you didn't quite put it in right (rubber sleeve a bit too far forward from pressing it into the hop up unit and is causing airleaks there.)

[Ghost Snake]

Did you readjust your hop up after installation? If I remember correctly, the Guarder one is harder than the stock one. So if you kept it at the same setting, it will be pushing down much harder on the bb, resulting in lower fps.

[stokes]

Clear hopup buckings are prone to swelling with an overspray of silicone oil. This swelling could disrupt the escape route of the bb. So therefor slowing down your shot and decreasing your FPS.

[CDN_Stalker]

The Guarder clear ones are labelled as 50%, meaning less than stock. The black Guarder ones are stiffer.

[cjfield1129]

I know that I installed it right. I have actually installed numerous Guarder clear buckings on guns for friends that I've upgraded -I must have not used as much lubed because they all shot at their proper FPS. I know this was installed properly. I reinstalled several times and even switched buckings thinking that the one in the package was defective or something. The bucking does seem to be loose in its fit around the barrel. Also, all chrono tests were done with the hop up off -that is why I' suspect the airseal issue. I will experiment with the given advise tomorrow and post back with follow up results.

[cjfield1129]

Just an update...
I removed the bucking and reinstalled a new dry guarder bucking and reassembled. The FPS was at 350 (low in the first place for a PDI 170) but dropped even more to 300. It was actually better/higher with the bucking sprayed with the silicon oil. I have a new Poly aluminum G36c hop up unit as well as a RH65 bucking on order. We'll see what happens then.

[MadMax]

Gah, I hate the clear buckings so I don't carry them. They're prone to tearing and oil absorbtion related swelling.

The black ones are ok.

[CDN_Stalker]

Want to know something, even though you've installed hop up sleeves & buckings before, doesn't mean you'll never install the occasional one incorrectly, just means you know the tricks to getting it perfect 95% of the time. I've installed a few dozen of them, every once & a while I have to reinstall and shift over a bit to get it perfect. Just saying it happens, not patronizing you.

[cjfield1129]

I understand and agree. I'm just dumbfounded at how every time I reinstall and adjust, I get different FPS ranges: 350 then 325 then 370. All the results are obtained when the hopup is off. I am using a PDI 170 spring and was chrono'ing at 405 before the fps drop after one game. I was a fan of Guarder clear buckings but now I'm rethinking. As I mentioned earlier, I have a KM RH65 coming. Is that a much more preferable replacement. Also, I installed the Poly aluminum hop up unit. The inner diameter is clearly a tad bit tighter. I am still using the Guarder bucking though and my FPS results are the same.

[Kampfer]

I had the same problem with a Famas a few months ago.

- First off PDI misspackage springs sometimes. (not in your case)

- nozzle might not be fully engauged before the shot

- lastly the Oring in the piston head doesn't seal perfectly resulting in loss of fps and inconsistancy in fps which shows up in the hopping of the bb (that was my problem)

Hope that helps. It's one of those phantom problems that I have to spend extra labor and time on.