Closest we have to a rifled barrel though.

The reason I brought up rifled barrels if that in target shooting,
bullet spin is of utmost importance. Since the projectile revolving
around itself will create it's own gravitational field, it can move
inside a pocket of air that will give it better down field velocity and
less sensitivity to cross winds.

Having said this, the factor in paint ball or paint soft is that the
projectile is filled with liquid. That liquid will resist the projectile spin
and can actually start wobbling which is worst than if it was not
turning at all...

So I was inquiring in what ways can bullet spin can be attained in Airsoft...

This is also a very interesting thread by M76 because Cartridge Overall Length
is an important factor in target shooting. If the bullet is too close to the rifling,
pressure buildup could cause mechanical failure. However, to much clearance
will cause the bullet to accumulate sufficient velocity to cause excessive
bullet shear.

In paintball, the outer shell of the ball is very thin, so bullet shear can very
well cause bullet failure in the barrel. This is why variable rate of twist
in the barrel will cause a softer rotational acceleration and will prevent
the balls from ripping their outer shell trough bullet shear...

Very interesting discussion...

Pierre

Our projectiles are very sub-sonic, and not usually prone to material failure during discharge or flight, unless you use cheap crap BBs.

The BB is lightweight enough and slow enough that gravity and air resistance affect it's trajectory more that anything else. That's why backspin is employed, to help overcome gravity and allow extra energy to overcome it as much as possible. Then, a polished BB will do as much as possible to cut through the air smoothly. Dimpling like a golf ball may help, but good luck making them in the billions needed, with good QC and still be as cheap as we pay now.

I think a rifled barrel for an AEG is a non-starter. The BBs themselves have too much dimensional variance to make that effective, and you'll either have under-spec BBs with no induced spin or over-spec causing a jam.

In that case, how does tight bore help Airsoft?

Do they allow greater initial pressure buildup before launch?

Yes, a bit. But the biggest difference is to keep the BB running on a strainght path after it's gained it's rotational energy from the hop-up.

In a standard 6.07-6.08mm barrel, the BB has some room to float around inside the barrel. It doesn't run perfectly centered in the barrel, as often the BB in less than 6.00mm. When you reduce the barrel ID, the BB has much less room to float around. This keeps it running as true as possible, and this translates into better accuracy.

If you go really small, like 6.01mm, you may run the risk of a jam if you use an inconsistant or oversized BB.

Can you explain the hop-up vs barrel ID?

I keep hearing about hop-up adjustments, however, I fail<
to visualise the relationship between them...

Pierre

The MOA measurement is something similar that I was thinking of... to create a reference to compare one's set up against.

I think in this way a lot of unnecessary upgrading can be avoided. I have recently discovered that you should not upgrade just because a component is *supposed* to be bad. Take the time to optimize the hop-up, and wear it in in that setup... you may be surprised. The stock barrel and hopup I now have (Kraken!!) are shooting 11 inch groups outdoors at 100 feet (measured, not guesstimated) and an incredible 6 inches if no outliers happen to come out. The outliers are decreasing in frequency (about 1 in 6 now) as the grease clears out the hopup (the first bb I ever fired was coated in thick, golden grease). I have so much confidence in the gun firing damn straight almost every time I pull the trigger. Certainly at least one out of a three round burst nails where the iron sights are centred, at 100 feet.

and to think I almost bought a tightbore and new hopup for $100, when the difference I could have obtained would have been so minimal as to be completely negated in an outdoors context with wind and foliage as factors.

I'm pretty sure that you are hoping for MUCH more than any airsoft gun (considering the nature of the gun design and the ballistics of a light BB) can produce regularly. Even at 100ft I'm 99.999% there isn't an airsoft gun out there that can even set a standard at that distance, even if "Airsoft MOA is 6" @ 100ft".

Now, consider what the airsoft guns are used for and you'd have a better chance. 5 shots at a certain distance, can you hit a guy that many times on semi? There ya go, the important part. My CA M24 shooting around 500fps, and when using 0.30g match grade ammo, can hit a 10" pie tin at 100ft maybe 6 times out of 10 shots, depending on wind. Indoors, I can improve on that to about 8 shots out of 10 on a peice of paper.

Expecting anything that can be considered a measurable standard is rather foolish when dealing with airsoft, unless usning heavy BBs (say .43g or higher) at 600+ feet per second, aka. make the airsoft gun a legitimate firearm (500fps+ and 5.7J+) and then a standard can be set for 100ft accuracy. Anything under that is impossible.

These standards can't really be followed.. mainly because most people don't know how far 10 feet is...

the ultimate test for a barrel would be, like you said, with all variables accounted for. also, tests should be done with the hop-up turned off. that way, BB accuracy will be raw and unobstructed.

sure we do, its about 5m ;):p

dont worry, i kid.

Staker, you raise good points.

Having a 1 MOA airsoft will mote make you a better
contender as strategy is by far the best tool for this game.

However, understanding Airsoft ballistics and how it all relates
does help understand the issues and concepts involved.

If for nothing else than maintenance, getting the best
of your gun add another dimension to Airsoft.

Meanwhile, here are some target shots from both mi rifles.
Note that I reload my own bullets and use Lapua 144 FMJBT
for the Swede and 168 FMJBT for the Savage.

Savage 12LVSS with Laminated stock and floating barrel, 308 cal:
http://img.photobucket.com/albums/06...ring_Front.jpg

.5 MOA at 100 yd

http://img.photobucket.com/albums/06...rget_2-870.jpg

Tikka sporter in 6.5X55, out of box:

http://img.photobucket.com/albums/06...ikka_Table.jpg

.25 MOA at 100 yd

http://img.photobucket.com/albums/06...et_3055COL.jpg

:D