Hop up isnt giving enough hop

[Jerryy]

Hi all,

I have recently bought a wellpro we09k (ak-12) and I've changed the spring in it as it was really underpowered from the get go (250 fps on 0.28 @ 0.8 joules), however when i was shooting it i had noticed the hop not doing much when adjusting the hop, there was practically no difference between on or off. since then I have taken it apart and replaced the hop rubber only to notice that the hop arm simply barely pushes it down, I've tried replacing the old little silicone nub that the hop arm pushes down and used the end of a rubber (eraser) as it is a bit stiffer to push it down more, it has made just a slight difference but still barely anything compared to my other RIFS, does anyone have any suggestions from their WELLPRO's or any suggestions at all. Thanks!

View attachment 136243

View attachment 136244

 

[Rogerborg]

Do you mean that there's barely any movement in the hop arm, or that it moves, but you can see that it's still barely pushes the bucking into the barrel?

Either way, it sounds like you'll just have to find a way to put more pressure on the bucking with a larger nub. The pencil eraser is a good shout, just cut it larger. Or use thin slivers of eraser, Sugru, or even pieces of electrical tape in a pinch to shim out between the nub and the bucking.

 

[Jerryy]

Do you mean that there's barely any movement in the hop arm, or that it moves, but you can see that it's still barely pushes the bucking into the barrel?

Either way, it sounds like you'll just have to find a way to put more pressure on the bucking with a larger nub. The pencil eraser is a good shout, just cut it larger. Or use thin slivers of eraser, Sugru, or even pieces of electrical tape in a pinch to shim out between the nub and the bucking.

it moves, but i can see that it's still barely pushes the bucking into the barrel is what im trying to say, sorry, what do you mean shim out between the nub and bucking, do you mean inside the actual chamber?

 

[Adolf Hamster]

looks very combat union inspired, although that's by no means an insult.

i suspect the issue is the arm length, on the cu's you get an equivalent linear movement from the pitch of the spiral but the arm on that well looks about a third longer.

ofc limited travel isn't entirely a bad thing, it's trading fineness of adjustability for range of motion.

one option is to pop some packing under the nub, as 'borg says pencil eraser although i tend to prefer cutting strips off a normal bucking into rectangles as they give a consistent thickness.

it moves, but i can see that it's still barely pushes the bucking into the barrel is what im trying to say, sorry, what do you mean shim out between the nub and bucking, do you mean inside the actual chamber?

the nub is the part that's actually pushing the bucking through the barrel window and into the chamber. they're usually round cylinders of rubber nestled in a little cup in the hop arm but can be in all sorts of wacky shapes or even moulded into the arm itself.

another old school mod is if the nub is particularly soft, replacing it with a snippet from a biro ink cartridge which is much stiffer and doesn't deform can also give motion at the expense of making the hop more sensitive (ie the gap between no hop, good hop and jamming is smaller)

 

[Rogerborg]

one option is to pop some packing under the nub

Yup, that.  Just cut a thin rectangle of pencil eraser or your material of choice, the same size as the hop window, and lay it on top of the hop rubber before putting the arm and nub back on.

another old school mod is if the nub is particularly soft, replacing it with a snippet from a biro ink cartridge which is much stiffer

Another good call.  Heck, the stock nub on my XR-5 was a tube of hard plastic.  And glued into the hop arm.  Very peculiar, but it did actually work (before I immediately binned it off for an Omega and Maple Leaf).

On that last point, what bucking did you fit?  Maple Leaf buckings generally do a decent job in most hop units.

 

[Jerryy]

looks very combat union inspired, although that's by no means an insult.

i suspect the issue is the arm length, on the cu's you get an equivalent linear movement from the pitch of the spiral but the arm on that well looks about a third longer.

ofc limited travel isn't entirely a bad thing, it's trading fineness of adjustability for range of motion.

one option is to pop some packing under the nub, as 'borg says pencil eraser although i tend to prefer cutting strips off a normal bucking into rectangles as they give a consistent thickness.

the nub is the part that's actually pushing the bucking through the barrel window and into the chamber. they're usually round cylinders of rubber nestled in a little cup in the hop arm but can be in all sorts of wacky shapes or even moulded into the arm itself.

another old school mod is if the nub is particularly soft, replacing it with a snippet from a biro ink cartridge which is much stiffer and doesn't deform can also give motion at the expense of making the hop more sensitive (ie the gap between no hop, good hop and jamming is smaller)

i see thank you for your help, the actual part that pushes down from the arm is just a plastic block and isn't adjustable or changeable in anyway (see piccys below) which doesn't help at all. 

View attachment 136250

View attachment 136251

 

[Adolf Hamster]

Looks like it has a bit of rubber in it, which could be swapped for something chunkier.

Or the packing method will still work