MOSFET front, battery back?
 

So I'm finally making the switch over to lipos! I bought the merf 3.2 because burst sounds like fun! I can fit a small battery and the mosfet into the buffer tube but it doesn't leave me enough room to collapse the stock at all.

I am wondering if there are any other common places to stash your mosfet? I am considering a peq or even just inside the front rail. Any issues with that?
How much wires is too much wire? Like overall length and resistance? If I am rear wired battery run wires through the mech box to the mosfet and back through the box to the motor? Would that be too much?( I'm confident I can physically fit and route the wires in and out)

I would appreciate any expert advice

Having a longer wire will contribute very little to the resistance, even 1 extra meter of crappy 22 gauge wire will contribute ~0.05 ohms in series with the motor (source) so it shouldn't present any inherent problems. Depending on how the gun comes apart, you may need a bunch of extra connectors and this can be problematic if at any point you have a weak contact.

Wiring a gun to have a FET in the front and battery in the back is a terrible idea. Much more effort than its worth, disassembly will be a huge pain in the ass.

Best bet is to get a crane stock and house the FET in the side tube.

Thanks for the input! I'm using the madbull socom Ace stock. Not interested in switching to a crane. I haven't made up my mind yet but I'm willing to put the extra work into disassembly if it means I can utilize the full function of my rifle day to day.

I honestly think its a better idea to get a smaller MOSFET. I only run 3034 or BTC FETs in my guns. I don't run Gate units anymore because they are shit.

Is there space in the socom stock to mount the merf vertically where the butt pad is?

I remember when the ascu was just out, juggles of AirsoftParts had the control box of it vertically in the skeleton stock on his shop demo unit.

That's a good idea, but no. Not with out some serious modifications. It's a solid chunk of aluminum.

the merf is too fat... burst fire is overrated. I have 2 triggermasters and a specter. I used burst fire for maybe 1 day before turning it off.

Logistically speaking, there probably isn't enough room to run the 2 main wires through the gearbox from the back to the front to the mosfet and back to the motor and then from the mosfet to the motor. There's barely enough room for 3 wires in the wire channels, 1 of which being a narrower switch wire for a fet vs the 16 or 18 gauge for the power wires. To back to front to back, you'll need to pass 4 main wires through the gearbox.

Just get a battery stock. Or hang a battery bag on the stock.

If you're confident you can do it don't let anyone tell you otherwise. Measure twice, cut once.

I run an HK style stock for maximum battery space (Lipo in each stock tube wired in parallel, FET in buffer tube) while still being adjustable.

The wire resistance is not a big deal, the hard part would be arranging the extra wires around the gearbox, inside the receiver, and still allow the body to close as they were. This will get especially annoying on a gun with tight space inside the receive, like a AR.
Wire keep getting caught in hop-up or charging handle is annoying, and could easily had their insulating wrap damaged and cause a short.
I once had a plan of a dual-battery G36C with one battery in the front and one in the back, and a small MOSFET in the front (G36 has much more wiring space in receiver compares to AR). But I gave up on that after I draw the wiring diagram.