Over hop only on full auto

Rod Slider · May 17, 2023

Hey guys,
cant figure this one out myself. I have a gun running a open bolt hpa engine and the thing shoots great. On semi.

On full auto all the shots over hop consistently after 30-40 meters. Everything works as normal if swapped back over to semi without hop adjustment

Only running 15 rps and I am unable to replicate the issue no matter how fast I spam semi.

Madbull red shark with ML omega nub, running hopup on the lowest setting which is a flat trajectory on semi on .32s

Any ideas on how to fix this? Was thinking about flating the rubber to see if this helps but thats just a hunch.

SiliconeSword · May 18, 2023

I think it might have to do with the hop either heating up or cooling down while shooting.
I run a closed bolt engine and have noticed that different ROFs will give me different amounts of hop, so I imagine it must be heat related.

I think maybe your best course of action would be an 85* 2021 Maple Leaf bucking as silicone is a lot less prone to hardness changes when temperatures change.
This may seem like an issue, but I would step back and ask yourself if it's really that bad, as usually when one is using full auto they are not aiming as carefully. I guess it all depends on how much overhop you are getting though, as if it's more than a body height tall at like 40m that may not be very good.

Rod Slider · May 18, 2023

SiliconeSword said:
This may seem like an issue, but I would step back and ask yourself if it's really that bad, as usually when one is using full auto they are not aiming as carefully. I guess it all depends on how much overhop you are getting though, as if it's more than a body height tall at like 40m that may not be very good.

I get your point, 100%. I’d be willing to just accept it if it wasnt a LMG build. The amount of over hop in practice means when shooting out lets say to 70 meters I’d be aiming for the feet. This I could live with but when you add people in prone at range to the equation its alot of guessing😅

As for the ML bucking I’m a bit hesitant to try just because I’ve never been able to get a open bolt system consistent with them. The feed lips tend to be too short and or soft.

RonSwanson said:
From a physics point of view could be multiple things
As solid materials heat up they generally expand
Could also be on full auto the nozzy isn't pushing the BB as deep into the hop rubber as much so is gaining more back backspin.

This could be it, the madbull red sharks are thick compared to most buckings so I’d imagine the expanding could be an issue. I’ll see if adjusting nozzle pause time on the Pulsar will make a difference as that is something that could efect the nozzle movement.

RonSwanson · May 18, 2023

From a physics point of view could be multiple things
As solid materials heat up they generally expand
Could also be on full auto the nozzy isn't pushing the BB as deep into the hop rubber as much so is gaining more back backspin.

Leo Greer · May 18, 2023

Your experience may vary, but I just put together a DMR build using the Pulsar and a Maple Leaf 85* MR.Hop with no issues. Hop unit fitment is a big thing though, since different hop units give you slightly different packing distances, and receivers affect this as well. I'm using a G&G rotary unit in a Tokyo Marui receiver, and it just about fits perfectly.

Rod Slider · May 18, 2023

Well fucked around and ended up flatting the madbull red and building a flat nub from sorbo.

Need to apply hop to get flat trajectory which in my head could mean that I just turn it down full auto shouldnt overhop.

Need to test properly but atleast it beams on semi and I have adjustment down available so could be good. Will see on Saturday

Over hop only on full auto

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