Dude, you crack me up. ASC should charge you a dollar a question. At least you can put together a sentence well and it's an easy read....
1. Pistols have short little barrels and any movement is greatly magnified by the time that the projectile reaches the target (and that's assuming the projectile travels in a predictable manner).
- Semiautomatic pistols have the follow things to consider.
1. The frame of the pistol is in your hand and so "fixed" to your body. You hand holds it and let's assume you hold it the same every time (or at least you can try to).
2. The slide is a "floating" assembly that rides back and forth on the frame....so in small differences it's not great for accuracy since there's play (i.e. slop, gap, wiggle room, etc...) between the slide and frame. What differentiates a great gun and a so-so gun is this fit. Tight enough not to wiggle around randomly, loose enough to work.
3. The barrel wobbles around in the slide...adding another point where deviation can happen. Because it releases, moves and locks up with every shot if it comes to rest differently with every shot, it doesn't matter how accurately you aim, the shot won't go where you're aiming. How little the barrel deviates in it's locked up (in battery) postion makes the difference between a great gun and a so-so one.
4. The sights are fixed to the slide (even if they're adjustable, they're essentially fixed in position relative to the slide). That's a good thing...since if they moved around then why bother aiming in the first place.
5. There's only three parts to support a 1911 style barrel. The locking lugs on the top of the barrel...these match up to the slots cut on the inside of the slide. The bearing surfaces at the bottom of the slide...these ramps push the barrel up and lock it into the lugs in the slide. And the "tip"/end of the barrel when it meets the slide.
6. You can't really adjust the lugs nor can you really alter the ramps of a barrel. As long as it jams tight when in battery you're good. But they don't...because metal wears. And if it was too tight, it'd get stuck.
7. You cannot really adjust the fit of the barrel to the slide...but you can hope that the parts that you get help you with this. You want as little play as possible between the barrel and the slide. Close enough for minimal movement...loose enough for reliability. Cone barrels can be fitted...i.e sand away a bit of narrow a big cone and you'll get a good fit eventually. Airsoft barrels are mostly undersized...and it's not at all easy/pretty/successful to add material back.
- a bushing takes up the gap between the barrel and the slide. But now you have an extra component that has to be right on. The bushing needs to not move in relation to the slide...and fit extremely well with the straight barrel. Straight barrels are straight (or at least as best as possible)...cylinders can be reamed a lot easier than tapering a cone barrel...so it's easier to precisely fit a barrel to a bushing. Sadly...again, airsoft parts are usually made with too much slop.
- In addition to the above...for airsoft guns there's the inner barrel. The inner barrel should have minimal movement with the outer barrel.
So...what you're trying to do to get the best accuracy is to get the inner barrel to be consistent with the outer barrel...the outer barrel conisistent with the slide and the slide consistent with the sights (usually the gimme part in all this). If you do this...the fit of the slide to the frame is immaterial in the most part...since what you aim with (sights) is consistent with what the projectile comes out of (muzzle of inner barrel). But a nice repeatable slide to frame fit is highly desireable since you can then let your training/muscle memory aim for you vs. making lots of small muscle corrections for every single shot.
NOTE: NONE of the above is really necessary for most shooting with an airsoft pistol.
2. Yes, correct
3. Dunno...reread Illusions post about not being able to confirm ahead of time. Actually, my comp gun has a SD MRP OPS Slide on it...but I don't want to disassemble it to check.
4. When a gun (pistol/rifle/howitzer/etc) is in firing position, it has returned to battery. Otherwise the action (the mechanism that is activated by the trigger and usually strikes a firing pin) is open. Return to battery is a common firearm term...actually has more to do with cannons being pushed into position than pistols I think.
You've got to google "how a pistol/gun works" and do some reading. Or download the Canadian Firearms Course book somewhere online. All firearms work pretty much the same...all firearms have the same basic components...almost all the "terms" are used for every make/model/etc...that's ever been made.