WE M&P Hop Up Fix – Part 2

Instructions on how to fix the WE M&P (full size) hop up issue – no adjustments in the dial.


Step 1: Acquire WE hop up arm & adjustment dial from WE M&P Compact (I will be ordering in some at work).


Step 2: Install and enjoy a working adjustable hop up.


But seriously… read on after the break for a slightly more technical analysis of the new parts from WE in the M&P Compact.

Quick reference note for the rest of this article – the WE M&P Compact parts are shown on the left or on top or first. E.G. in the picture below, the WE M&P Compact hop up chamber & barrel is on the left, whereas the WE M&P full size hop up chamber is on the right.


The Compact’s hop up arm looks to be of a similar size and shape to that in the full size – with the exception of a deeper indentation where it presses down on the hop up bucking.



The stock arm found in the full size had trouble hopping even a 0.25g BB when adjusted, yet this arm from the Compact is overhopping a 0.25g at approximately 1/3 of the maximum hop setting or less.



The adjustment dial seems to fit much more properly between the two halves of the hop up chamber. If I were only to have access to this wheel, I suspect that it would still adjust with my modified hop up arm (though with less hop up effect as per the shallow indent on the arm from the full size M&P). The hop up chamber halves seem to be the same dimensions as before – changing these will have little to no effect on hop up adjustability, from what I can tell.

The angle of adjustment within dial looks slightly different to me, I’m not quite sure what it is – it appears (to the naked eye) to allow for a greater difference between 0% and 100% hop up, this probably is why the arm turns more smoothly inside the wheel.



The stock WE M&P bucking uses a proprietary barrel cut specific to the WE M&P series (including the Compact). I’ve purchased the A Plus Studio hop up & 6.01 barrel set a while back, in order to replace the typical crappy factory WE hop up rubber for a more consistent one. Now that my hop up is adjustable, I can actually see the inconsistencies with a clean factory WE hop up rubber as versus a clean A Plus Studio’s aftermarket rubber. See the pictures below for a comparison of the two buckings and barrels – do note that the A Plus Studio bucking does not have the alignment fin sticking out of it to fit into the right half of the hop up chamber.


This being said, if you preferred, you could install a Marui-spec inner barrel to use a Marui-spec hop up rubber, as I’ve read about a few guys doing over the internet (PX4 inner barrel length is approximately the same as in the full size M&P).

Note that the factory rubber has a very similar “U” shape to that found in the earlier A Plus Studios Devil hop up buckings – the “V” shape in the aftermarket A Plus bucking is similar to that they are currently using in the Gen 3 bucking for AEG and Gen 2 for GBB… anyway, this similarity leads me to believe that A Plus Studios may have had some input on the bucking design for the WE M&P. Hence the somewhat proprietary hop up bucking design – unless the user replaces the inner barrel and hop up bucking, they can only be replaced with barrels and buckings designed for the WE M&P. Also could be why A Plus released their hop up bucking/inner barrel set so soon after the release of the M&P (though Joseph (a.k.a. “CYC”) is a mutual friend of both WE and A Plus – I already know they have a good relationship with each other). If this is the case, its a good business decision, though kinda annoying for this end user who wants to upgrade the hop up bucking using ones I already had lying around.


The A Plus Studios 6.01 tightbore precision barrel leaves a bit to be desired in my books – it appears to just be brass with a shiny coating – though this coating doesn’t even cover all of the barrel (the brass is exposed around the crown of the barrel, as well as in the hop up cuts). Consistency within the bore probably isn’t perfect, as the flight path of my BB’s on the old hop up unit I was using with the upgraded A Plus and stock WE hop up bucking was not as straight as I had been expecting for a 6.01 barrel and consistent 0.25g ammo – my old Tokyo Marui Glock 17 shot far better, even though it was using a much less advanced hop up bucking.


Now that I’m writing about this, perhaps the more inconsistent BB flight path is due to the Tokyo Marui hop up arm being shaped more like an “H” than the flat shape on the WE M&P hop up arm…? I’ll do more testing on this at a later date, I.E. when I have access to replacement parts in case I screw up.


On a mostly unrelated note: after holding the M&P Compact for a bit, I think I may want one, though I’m still debating between this and the Tokyo Marui Detonics as my first sub-compact pistol.

Part 1 – Review

Part 2 – Update

Part 3 – Full-Auto Fix

Part 4 – Full-Auto Fix Video

Part 5 – Work-In-Progress Hop Up Fix (not the most current info I have)

Part 6 – Working M&P Compact Hop Up!

Part 7 – WE M&P Hop Up Fix Part 2 (this is the most up-to-date fix I know of)


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