1. I assume the weight of the BB will affect the performance of the gun in terms of accuracy and range - increasing the weight of the BB increases the accuracy but decreases the range and vice versa? How much of a difference does this make? What weight should I be looking at if I was to use the M14 at range? I assume I'd want a heavier BB to increase accuracy but how much range am I going to sacrifice?
2. My local Airsoft field doesn't have a BB weight limit (nor an FPS limit it seems) but it does have a Joules limit. This is from their website:
2.1 All weapons used will have to pass a chronograph test using the weight BB you intent to shoot and conform to the following limits:
Full Auto weapons, Pistols & Shotguns MAX 1.15 joules
Semi Auto Locked (DMR's) MAX 1.88 joules
Bolt Action Rifles MAX 2.32 joules
Does this mean that I could get the gun up to 380 FPS using .28 BBs and it would be legal?
3. Would the stock FPS be sufficient in terms of range for what I'm looking for or would I need to upgrade it somehow? What would it take to get the FPS up towards the 380-400 range?
With such limited experience, I don't really know what FPS actually looks like in the field. It says the stock FPS is 340 for the M14 but I have no idea whether or not that's sufficient for a DMR style weapon. Isn't this what most full auto guns are and DMRs/snipers are around/above 400?
Thanks again for the help so far and thanks again in advance!
1. Heavier BBs tend to give better range AND accuracy. However, AEGs have a thing called cylinder to barrel ratio which I honestly don't understand all the intricacies on (the airsoft teching hole goes deep...), but what it basically means is that most AEGs have a sweet spot for BB weight at certain powers and it's different for every set up; helpful, I know. At 1.1J, running a .48 probably won't give a huge boost in performance and that's assuming the hop up can even lift it, but it will provide a huge boost in running costs as a bag of 1000x .48g BBs is between £25 - 30, where a bag of 3000x .32g BBs is between £18 - 20; triple the ammo, about 33% cheaper.
Joules, at the end of the day are a measure of kinetic energy. I'm going to dive into poorly explained science here because the last time I studied physics or mechanics was when I was 18 and doing my A-levels. When a BB is fired, it has a certain amount of kinetic energy going in the direction of (hopefully) enemy players and is being slowed down by air resistance, pulled downwards by gravity and also affected by things like wind direction, rain, pesky leaves getting in the way etc. The heavier the projectile, the slower it will leave the barrel (assuming the same kinetic energy), however it will also take longer to decelerate as the mass of the projectile requires more resistance to lower its momentum. A good example is imagine throwing a cricket ball with a certain amount of kinetic energy and think how far it will go compared to a balloon thrown with the same amount of kinetic energy.
As I said, I haven't studied it in years and I'm awful at explaining it (I was more into statistics than mechanics). There are plenty of sources online that will explain kinetic energy, momentum, deceleration and all that lovely physics stuff better than I can.
2. Joules are far better than FPS for testing power. I run gas guns and I could probably get my m700 firing at 350fps on a .2 (so, no MED), but then being around 2.3J on a .48 thanks to a wonder called joule creep that is prevalent in gas platforms which would be unsafe to fire up close. (it's not a wonder, I hate it and am constantly wrestling with it ?)
2.1. You could, though if you're looking to go the DMR route it will cost more than £250 to build a decent one and require you to open up the gearbox, which I do NOT advise for a new player; hell, I've been doing this for years and I still don't do gearboxes. I just don't get them, no matter how many times I try. To build a DMR, you'll likely need a metal-toothed piston, high torque motor and a stronger spring at the very least, but you'll likely want more things like a full cylinder (most stock ones are ported which means you get lower air volumes which is not what you want for a DMR), MOSFET and better gears. Also, you start wrestling with MEDs as soon as you go over 1.14J, which means you can't shoot at anyone who is within a certain distance of you, whether it's 20 or 30m (the most common MEDs. 30m is the most common though) which means you would really need some sort of pistol or secondary to go alongside it. Some sites enforce that you must have a pistol or secondary if you want to run anything with an MED; my local site very much does.
However, as an added piece of advice, if you're running at 1.88J, you want to be using far heavier than a .28g BB. For me, I'd be looking to run .4s at least in a 1.88J build, preferably heavier if the hop up would lift it without dropping the power too much.
3. Stock FPS is more than sufficient. 340fps on a .2 means it will be pretty close to 1.1J and is exactly where mine is shooting at the moment (it's about 1.07J). Power does impact range and accuracy, but hop up and barrel setup impacts it far more. Also, not all sites have the same DMR rules, so if you set it up for 1.88J, you wouldn't be able to use it at other sites; my local site for example has DMRs at 1.64J and some sites go as far as 1.48J as a limit for DMRs. Therefore, if you want to do a DMR build, my advice would be do it with something with a quick change spring system so that you can adjust the power fairly easily without having to open the whole gearbox, which you don't want to be doing with an m14 at least because they're fiddly to get apart. I can go on at length about the pros and cons of building a DMR, but the TL

R is that I generally don't think it's worth it because bolt actions are better at it.
Aaaaaand, it appears I've built another wall, though it is big and beautiful... ?