[becklr1]

Pellet or BB?
Why do people thing pellet shapes are not good?
Why do people automatically assume the velocity needs to be higher?
Light pellet or heavy pellet?
Pellet means no hop up.
what is the problem?

My sense is a light pellet is unstable, a heavier one is more stable. But you then need to prevent air loss so the barrel needs to be tight. Then of course you have the problem of pushing it down the barrel. I ran some tests and I found it is quite easy to make a bb tight enough to stop the piston form moving it when compared to a lead pellet gun it is quite loose even is the airsoft gun will not move it.

The "strongest" spring PDI sells is a SS 5000 which rates in at a measly 12.5 lbs per inch which is measly in air gun standards.

Anyhow, I am going to try it in my design as it accommodates both types, round BB and a pellet style (needs to be made). That is like a year away still.

Until then, anyone plan on trying a simple test. perhaps use a straw epoxied to a BB and then partially filled just as an thought? I would try but but don't have an airsoft gun anymore and my son won't let me dissect his he saw what happend to mine.

I think there is merit to a shirted round. I know there is. So who is going to test. Woogie?

 

[lainthecity]

Well, a BB is spherical, so backspin can be relatively uniform, allowing the bb to travel further under low velocities. Pellets cannot use the backspin affect (Bernoulli's Principle), so they must, for the same weight, be shot out at much higher velocities. If the pellet is made of plastic, and it deforms (smooshes) on impact, the energy dissipation will be longer, so it will be safer (relatively). Of course, pellets have different aerodynamics, but I'm not an aerospace engineer (or any engineer for that matter-yet), so I can't tell you how it's flight characteristics are different. From this argument (sphere vs. pellet), I can think of 2 different methods. One, make your own pellets and test, (preferably on a multi-psi/fps rig like an hpa set up), or 2: use some fancy cad/modeling/simulator program to design a pellet, then test.
Also, take into consideration the back end of the projectile (what the air pushes). BBs are round, pellets are usually concave because of a hollowed skirt.

 

[becklr1]

2 minute CAD mock up. probably cost $1 a piece to make.

 

[aaron2269]

$1 dollar per pellet maybe an ok price in the testing stage, but I won't want to play airsoft shooting a hundred of them a day.
There actually have been pellet shooting airsoft replicas, but they have all been phased out of use and ammunition is impossible to find.

I may be able to draw somthing out on CAD and try it out though. My father is a designer at his company and they have a rapid prototype machine.

 

[becklr1]

Yes I am talking prototype prices.

Let me see what I can do as well.

Those pellet airsoft guns, how did they work?

 

[aaron2269]

They didn't use a hop-up. I don't know much about them other than that.

 

[becklr1]

So that one I mocked up is more like a BB with a skirt. Hell someone has a wood lathe, make one out of wood. Oh, that gives me an idea, a dude at work makes pens with a hobby lathe. I have rode of Delrin from discarded ideas. I bet I can have him turn a few on the lathe. Also have a co worker with an ABS 3D printer he made.

 

[aaron2269]

My dads going to make a few of the pellets I designed with the ABS 3D printer that is at his workplace.

 

[becklr1]

Sweet!

 

[awagg]

http://www.airsoftsniperforum.com/phpBB/phpBB3/viewtopic.php?t=2021

To answer 1 and 2... cause everyone shut me down :/

But what I think is that there needs to be a lightweight pellet, and one that gets it stability from the rifling of the barrel. I think the rotation of the pellet will outweigh the cons for the lighter pellet. Think .20/.25g pellet getting shot at 550-600fps.

Sadly, $1 a piece is pricey, especially for a disposable round. You might want to try a more of an indoor target range with cloth to dampen the impact, keeping the form of the pellet, so you can re use it. Outside testing isn't really feasible for disposable, $1 a piece, prototypes.

 

[awagg]

Here is what I said on a different thread. Make sense to you guys?

You need to remember that bb gun pellets are metal, and as a result are more dense than airsoft bbs, or theoretical plastic airsoft pellets. This means that at 600fps, scaled to a ligher round = much higher fps. Then, you need to increase size from .177 to ~.236, again still plastic, and lower the fps to safe levels.

Not valid. Heavier bb's are more effected by gravity, and drop faster. Therefore the airsoft bb would drop slower, allowing for a lighter spring, bringing us to where we are right now.

Someone needs to test!

 

[lainthecity]

... Considering low grade pellet guns shoot accurately at 600 fps with only some drop, you're almost field ready...

My comment was based on yours, that if a pellet gun shoots a metal pellet @ 6oo FPS, and you made a plastic pellet of the same caliber (.177), the plastic would, just like in airsoft, travel much faster because it is lighter. But because we are looking at 6mm (.236 in), the rounds are much bigger.
My proggression was:
material/fps/caliber
[email protected] - pellet gun
[email protected]+fps.177in - (lighter round= higher fps)
[email protected]?fps.236in (6mm).(factor in increased wind resistance for a larger round)
I hope this clarifies my earlier post, but I was trying to say that changing the material from metal to plastic, and increasing size, would give you some fps based on the weight that would probably exceed field limits (1-2 joules).
Again, it was more of a guide for testing plastic rounds, what they are compared to, and that testing was needed.
Also, you have to remember that pellet guns go all the way to 1200+fps, but those ranges are usually for hunting small game, and definitely unsafe for airsoft.

 

[bobgengeskahn]

Ok, since this is more the route I am debating on, here are some references that I have found that might be useful to you guys:

Another forum thread on this:
http://www.airsoftretreat.com/forums/index.php?topic=11432.85;wap2

Another thread:
http://www.airsoftforum.com/board/lofiversion/index.php/t43151.html

Another manufacturer:
http://www.rap4.com
These are really neat ideas to work off of, mainly because of how compact they area combined with the realism factors.

Another thread that is better showing some of the Asahi M40 rounds:
http://airsoftpacific.com/viewtopic.php?t=606&view=next

 

[becklr1]

I am not shutting you down. I think is is feasible. I plan on trying it in some form. I designed a chamber to work with both so I can see what works.

Dang, I do not think RAP4 makes those anymore. That Asahi design in nice, like a tadpole. Look top nature for ideas.

What drives me crazy about airsoft is people talk to death but nobody tries anything and debates like they know something when in fact outside of a Revell model have never built anything but somehow they are experts on fluid dynamics.

They may know something they may not, without empirical evidence everyone is full of crap. Who cares what people say. Who cares if you are not right.

Both of you, just do it my man, just do it, gather some data points and then refine.

Hell my whole deal may be wrong too and may fail. Even if it does I have a lot of data to use to refine and I'll have a unit to build from.

Phone conversations through the air? Your crazy it is impossible. See the point.

 

[awagg]

... Considering low grade pellet guns shoot accurately at 600 fps with only some drop, you're almost field ready...

My comment was based on yours, that if a pellet gun shoots a metal pellet @ 6oo FPS, and you made a plastic pellet of the same caliber (.177), the plastic would, just like in airsoft, travel much faster because it is lighter. But because we are looking at 6mm (.236 in), the rounds are much bigger.
My proggression was:
material/fps/caliber
[email protected] - pellet gun
[email protected]+fps.177in - (lighter round= higher fps)
[email protected]?fps.236in (6mm).(factor in increased wind resistance for a larger round)
I hope this clarifies my earlier post, but I was trying to say that changing the material from metal to plastic, and increasing size, would give you some fps based on the weight that would probably exceed field limits (1-2 joules).
Again, it was more of a guide for testing plastic rounds, what they are compared to, and that testing was needed.
Also, you have to remember that pellet guns go all the way to 1200+fps, but those ranges are usually for hunting small game, and definitely unsafe for airsoft.

Here's what I'm saying:

pellet(600 fps) --> lighter material (say 850 fps), but the lighter material will drop slower than the pellet --> reduce the fps (say 600 fps) --> and then we're good!

The no hop still doesn't greatly effect the BB's flight path because the bb will have less joules than the pellet, but is lighter, so won't fall with gravity as much. The barrel rifling, I think, will even out the flaws of a lighter round getting shot at a higher fps.

Anyways, it's great that someone is going to try to make some! Post some pics of the finished product!

 

[becklr1]

Sadly, $1 a piece is pricey, especially for a disposable round. You might want to try a more of an indoor target range with cloth to dampen the impact, keeping the form of the pellet, so you can re use it. Outside testing isn't really feasible for disposable, $1 a piece, prototypes.

Good news is can't imagine a large scale run would cost any more than a good BB would.

Sadly. prototyping means low volume custom work which is always costly. It is the nature of manufacturing. I have some parts that are $175 a piece with a volume of 3. With a run of 50 price drops to like $20.

Scale pellets into the millions and you can likely get a few for a penny. But the set up cost for capital expense for machinery is really high.

For protype you wold have to catch them in cloth in a box and reuse them. then again it is a sniper round, it is not like you are trying to spray with an AEG. The idea is to test precision.

Alas, we are not trying to determine manufacturing feasibility, or debate production costs, we are testing a theory. For a few hundred $ and lots of personal time it can be answered. take your time and do it over a few weeks or months. No hurry. I'll do it but not until I have something to shoot it with and that is a ways out.

I saw you can buy casting kits for hobbyists. On youtube a guy casts with silicone using a Lego based mold. Check into silicone casting. Companies make all kinds of stuff for the craft and hobby community!

 

[aaron2269]

Well I have free accsess to a FDM prototyping machine and I can have a bunch of the pellets I designed produced in a single batch.

The pellets will probably be more precise than standard bbs, but without hop-up range will be lacking. In full scale production the rounds would have to be made from a frangible material so they can be propelled at targets with higher speed but still remain safe. Though that raises another issue of the durability of the round before firing.

 

[awagg]

Yeah I totally get the manufacturing costs thing. Also, I've been thinking of buying one of those hobby cast things for airsoft and other hobbies of mine. Do you think resin would work for a prototype? It's fairly strong, but brittle. I think it could work for my hop up thing, but not sure about bbs. Maybe a one use thing, because they will almost definitely break on impact.

 

[woogie]

FORGET ABOUT THE HOPUP CHAMBER FOR THIS THREAD.


If we are talking about a pellet shaped ammo, then you wont need, and can't use a "modern" hop up chamber. Think about a normal rifle. If you are going to go with this style of ammo you are going to have to have some kind of rifling inside the barrel. No I am not sure that a TK twist barrel will work.

Though if you were able to make the plastic soft enough to be able to "grab" the rifling to spin it. Again much like a football in a spiral throw. If you are able to make the ammo soft enough to grip onto the lands and groves, then when it hits a player, they should smush.

With the "smushing" of the round a great majority of the rounds energy will be expended during this process. And thus the thought of possibly allowing us snipers to use a higher FPS to once and for all gain the much needed range. As well as the side affect of added accuracy

Remember...... the less parts in the system. The less spots there can be a problem. No seals or anything to worry about any kind of air leak.

 

[becklr1]

Yep, reduce parts involved with exquisite hop ups first off. Pellets then go one step farther and remove hop ups all together. Then reduce variance. I do not think for ranges and speeds people use airsoft guns for rifling is needed.

I think there is merit to it. But ya someone should start a hop up chamber thread to keep the discussions clean.