Sewdhull

I d agree here, alignment of the barrel would be really tricky.

You will note that there is no optimum barrel length for a cylinder volume, there is a range of ratios and this is because of the other variables, air pressure loss and starting pressure, BB mass, hop setting, barrel bore and general quality. Also what your goal is for the system. Ratios quoted like 2 to 1 etc are to allow there still to be useful pressure in the system so the BB is still accelerating in the barrel, still supported by an air cushion. In this case and any case where there is more than 1 to 1 ratio(without losses), a stronger spring will allow more energy to be imparted to the BB in the same length of barrel or keeping the same spring allow a longer barrel to absorb more energy in a longer time or combination of the 2. In a zero loss system with 1 to 1 ratio there would be no purpose in a longer barrel, regardless of spring strength because altho average pressure would be higher it would still be atmospheric when the bb left the barrel. I too enjoy flecktarn kit.

The spring is very much the limiting factor, if you could use another stronger spring I'd guess the gears and bearings would give up.

Check out begadi, they have flektarn stuff of various types even tho they are over seas. Ive ordered from them without issue.

Life batteries are great, their main advantage is that they don't self sustain a fire like lipos do, you need extra outside heat to get them to keep burning after you have stuck a nail through them and they are also more tolerant to charging or discharging abuse. They work fine in airsoft guns, I got a cheap one and its perfectly servicable.

I've had no batteries catch fire or explode, except some nicads back in the 70s which overheated exploded and melted some carpet, in 50 years. I store my batteries in ammo boxes partially charged nowadays, but before that just looked after them, threw away the puffies or physically damaged ones and use a decent charger. I'm also older than you're dad, so lets not use that as any factor in batteries catching fire. 58 being old.. Pah If you have a damaged lipo ( they are only protected by a thin plastic pouch) chuck it. if you have a cheapo charger, chuck it. If you have electrically abused the battery, chuck it. That's how to stop batteries nuking. Don't use old batteries, if you have been using a battery for Airsoft for a year get a new one, you've likely dropped your battery more than once, either in the gun or just being lazy and chucking it on the table. Lipos are soft and will deform if you drop them. I neither charge my batteries attended or place them in a nest of kindling, just use sensible charging currents and a proper balance charger.

Air pressure behind the BB is probably the most important criteria for stability in a barrel. Enough to push past the BB and stabilise it. Longer barrels will need the same pressure for longer and shorter barrels may other issues of their own like insufficient time to stabilise or excess pressure on exit causing issues, I don't know. I do know that I can balance a Malteser in the stream of air from my lips using he same principle that exists in when air pushes past a BB in a barrel. The problem is that even those ppl who try to control the environment leave numerous variables unaddressed and then claim a conclusion. HPA guns stand the best chance of showing the value or not of a longer barrel ( On accuracy) because of the constant pressure, but the complex interactions before the BB exits the barrels make drawing conclusions from experimentation tricky.

It is easier to hold a lighter weapon steady than a heavier one, the addition of a shoulder stock to a pistol is a great bonus to accuracy. It's not about the barrel. Barrel length and bore don't affect accuracy until they are at extremes. BBs don't rattle around the barrel on the way down, they are guided by equalising pressures around the BB, keeping it central and straightness and uniformity of bore will be the primary factors affecting accuracy. There is a school of thought that wider bores allow a steadier passage of the BB down the barrel, pressures will equalise regardless of the bore.. again within the extremes. Clearly hop matters but is outside the scope of this thread.

Not all spring guides will accept a bearing, Lozart is correct about bearing sizing and simply bearings I have used alot for pretty much all my bearing needs. Fit a bearing at the head end if you can rather than on the guide.

The corrosion occurs all over the contacts, not just on the parts that face you. Gotta take it apart to see.

check for corroded contacts in the cap and at the base of where the batteries live

You haven't cycled the gearbox with the receiver off have you? Just run the motor? I was thinking you had cycled the gearbox... I would do this and observe the cut off lever and the trigger trolley, check the trigger itself catches the trolley again. The fire selector plate if it moves ok, wont be the issue. The cut off lever can be trapped in the receiver but its more likely the trolley getting lifted and not getting dropped again. You should be able to see it all happen through holes in the gearbox case near the cut off lever or cycle just the trigger, trigger trolley and contact block with the sector gear and cut off lever in place in one half of the gearbox. A new trigger block and cutoff lever costs very little tho

Look at the cut off lever and fire selector plate. These together with the trigger trolley allow single fire. Otherwise you'd get auto all the time. The receiver can pinch both the fire selector plate and the cut off lever. Is the fire selector controller installed with the receiver?

Gbbrs have the advantage of a reservoir of gas to keep the pressure up until the BB has left the barrel. This means that a heavier BB will continue to experience the same pressure as a smaller BB but for a longer period of time and so gain more energy. Since the pressure is maintained after the hop, the proportion of the energy used by the hop to spin the BB is less relevant, so more hop can be dialled in while maintaining BB forward energy. With an AEG you have a fixed amount of energy to impart to the BB. If you use a heavier BB and have pressure left over at he end of the barrel when the BB exits you will still see more energy in the heavier BB. The amount of pressure increase in an AEG will decrease the moment the BB starts to move and then pressure will peak and then reduce. Getting the reduction in pressure in the right place/time is the goal for voluming. For both types of gun, hop quality matters but for AEGs in particular tuning to hop and shoot for a BB weight needs to be done at build time.

Take off one of the spring bearings if you have 2. There's no reason to have 2, and you will reduce the preload by doing it. Either you've assembled the gun better this time or the springs are not rated correctly. You shouldn't be seeing that much difference between the springs altho the rps should be lower and may have addressed the timing issue if there was one. Unless you are using a known set of parts that works in your gun specifically, changing one thing at a time is advised. You wouldn't normally need a delayer unless you were getting feeding issues.

if you are getting 28rps that seems ok, you are probably being limited by the battery. I unsure that you need all the things you have in place. If you had PME you'd be hearing the gun chewing itself to pieces. If you are losing fps on auto its, to be expected to a degree, but you might be pulling the tappet plate back early... you'd need to look at how it cycled out of the gun manually

Use a hole saw on some sheet perhaps

If the current bucking is hopping whatever weight bb you are using, properly then it's fine. You'll be seeing similar fps at the hop as everyone else, the weight of the bb will matter more and you should have plenty of adjustability to offset the increased spin on the bb.

Web based calculators for me, faster by a long way and no typing if you use voice in google or any of the other assistants if you are after converting one thing to another. Excel is not really for this kind of thing, unless you always have it open or are automating such conversions for some reason.

These sort of springs are plated or they are stainless and once the plating has gone they will corrode really quickly, altho silicone grease will delay this if you lather it on. The caps can be disassembled and new or replated springs installed. If you cant get the springs out from down the tubes, probably out of the diy guys skill set, then make a good job of the caps, since they are most likely to be corroded. If you use vinegar, or any acid really, you'll just convert the corrosion and not get conductivity back. So I'd suggest either, buying new caps, https://www.ebay.com/itm/204243395541 or better in my view, pull the spring out and buy a suitable spring. You can measure it once its out. https://www.amazon.co.uk/Springs-Stainless-Conical-Return-Battery/dp/B0CSTB8GG2/ref=sr_1_3?crid=1O9YER0FVN393&dib=eyJ2IjoiMSJ9.EA9SkWaZ-6tQyvsw_8AdTYk6eyxD7fvtxN-tkAYJdB8qQZj9GhrM4G-F-hHK32XnL8uSoswCe_snH7IjwJenFjxAk9u5uNXbhCwxpWx87890vafNMPg-O97_WwuEnTiVs4lMwxdoJJN6p5STRDjcRQgZhueU5NRVKtC7wg2jCEFk9z7He_MvTLvQjpWFCfwvUC2yoWgYZKJUu0-h6IBlcLA84c6Iwg5NNaJ2WQRsGuI.l9JHnRDxVHevoAfdELq9vSsvXaUrJJa9MCbTKYRPd00&dib_tag=se&keywords=battery+conical+spring&qid=1724791764&sprefix=battery+conical+spring%2Caps%2C51&sr=8-3 clean the caps with some abrasive to reveal the aluminium surface and pop a spring in with grease. Brass ( not steel) wire brush the threads. Stainless will galvanically corrode with aluminium if you dont grease it or keep it dry.

you can charge the battery without the balance connector

This is true altho any gun with an excess of energy in the spring will create creep with heavier bbs, just because the extra time the bb spends in the barrel soaks up the extra energy. DMRs and BASRs have typically longer barrels and larger effective cylinders, stronger springs too, but for creep its just the excess energy that matters and the time to utilise it.

I can't understand the message here.

Use the croc clips on the Tamiya connector, as above you need to match the wire colour cos you may have a battery of either polarity on those Tamiyas. My suggestion would be to ditch the Tamiyas and pop on some xt30s or xt60s if space isn't a problem. I know ppl like the Deans, but its large compared to the xt 30s and the xt60 is better in every way. It is however satisfactory in airsoft.

Invest in a couple of adjustable nozzles which have helped me greatly with fault finding if the nozzle is suspect. Once you have the right nozzle length you can go buy the right one. Also tappet plates can be bent forwards or back wards at the time of manufacture and/or have mouldings that prevent them going fully forward. You can heat the tappet plates to get them back to 90 degrees and remove the mouldings. Some times the gearbox itself has casting protrusions which catch some tappet plates and not others. Both my mp5s and g36s have a style of hop unit that locates loosely into the gearbox. I mod mine so that they are better located by sleeving the hop and drilling the gearbox.