Feed-paths on bolt rifles
 

On the bolt-action sniper rifles, what is the feed system like? If someone designs a new and improved airsoft pellet that's oblong or something, do you feed them in by hand?

Yep. Pretty much.

Nice, thanks. Now all I have to do is design a new improved pellet:)

The problem is if you want any hop-up at all the pellet must still remain round like a bb. The only improved ammo design I can see is if you made bbs that are all the exact same size (ie 6.00mm)

You also have to keep in mind that your goal is to touch the other player, not make a hole in him.

Pointed pellet, or bullet shaped would be more acurate, stable and cool, but it's not good for airsoft.

You could attempt recreating the Asahi blade-bullet ammo? But, like stated there would be no hop-up, and I dont think too many people would be extatic about getting shot by that.

If you're going to go to the trouble of recreating the Asahi blade bullet, please, for the love of all that is holy in airsoft:

REMAKE THAT WHOLE SYSTEM!

Pre-charged shells has got to be the slickest idea for a sniper system EVER.

That rifle and that system are my personal airsoft holy-grail.

That, and a system similar to tanaka's new shotgun - Pre-charged shells with BB's in them.

If you use oblong pellet the best way to stabilize (sp?) it's trajectory would be to use a rifled inner barrel, which will give a spin to the pellet, no need of hop up. If you don't use a rifled barrel nor a hop-up tje gun would shoot like a musket ie: anywhere but the targeted area. But here the pellet would need enough spin and enough velocity to keep a relatively straight trajectory.

As for the potential penetration ability I believe that is the ends are round enought the pellets woudn't have more penetration power than actual BBs. If the weight and velocity are equivalent I think that the effects on human bodies would remain equivalent. Of course if the pellets are sharp the will be more promt to cause bodily laceration.

It would be an interesting study to complete.

Thanks for the info on that Asashi thing, that's awesome! The only problem I can see with the cartridge design is that you'd lose the cartridges. Interesting pellet shape they have, though.

word up to that

I'f you're going through the trouble of making bb's that are perfect enough to be used in a rifled airsoft gun you may as well just use bb's. IIRC the flintlock in my basement fires pellets through a rifled barrel.

A more precise pellet would be great. We could drop the hop up system and just aim with a little arch. If the pellets were consistent from shot to shot it wouldn't be a problem.

if the system could be worked out competently (barrel and twist, replacement of the hopup system) then it would not be difficult to adapt it to AEGs as well, all that would need to be done, is to re-shape the magazine shape, and elimination of hi-caps, as they would not work well with the shape getting in the way of efficient loading (that alone is a good arguement). Producing pellets would not be as difficult, because you would just need to make a differently shaped mold.

While it would be a lot more accurate, range would be complete shit. Have you ever tried hitting a target at 30 yards with a pellet gun shooting 495fps? You have to aim 6ft above the target. If your field restricts use to 400fps, good luck hitting anything over 40 yards. Your scope wont have anywhere close enough elevation adjustment to compensate.

Seems like a trivial reason not to try. If accuracy is possible, I'm sure technology would move to catch up. Until then you could just hold-over.

And for the record, shooting logs with a .22 air rifle long-distance is a very rewarding experience, the longer the delay from pop to thud, the cooler it is.

Technology? What are you talking about? It's called basic physics. I'm not going to do the calculations, because honestly, I dont remember shit from high school. But if someone is 50 yards away from you, and you have to aim 12 feet over his head, its just not going to work. It has nothing to do with technology. To make this feasible, you would need a muzzle velocity in excess of 1000fps, minimum. If you can find people to play with you, then go for it.

I appreciate the input, thanks. But maybe you could show me just a little bit of the math?

For instance, to get that high a MV you'd need a light projo, and if you've ever tried to crumple a piece of kleenex and throw it across the room, you see why that's no good. MV wouldn't trump retained velocity, in my opinion. Airsoft pellets right now have poor exterior ballsitics because the design is poor. Poor ballisic coefficients, secional densities, form factors, all of it. I'm not saying a better pellet would solve all the problems, but if it went straighter, and had 50% more range, wouldn't that be worthwhile?

A bullet shaped pellet will travel in a parabolic path because of gravity. I think Ghost Snake is just saying that the range would be poor for such a pellet because airsoft velocities are quite low. The pellet wouldn't fly much farther than current bb's do now with hop-up turned off. A good bullet shaped pellet would be more precise, hitting the same place each time, but would need to be lobbed at a target far away. As the distance of the target changes, you would have to aim higher or lower. This won't be as a big of a problem if the gun has a good graduated sight. Hop-up makes bb's fly in a straight line, not in a parabolic curve, so you can just point and shoot. The back spin gives the bb lift to fight off the effects of gravity so the bb stays airborne longer.

If you could some how give give a bullet shaped pellet lifting properties, that would be an interesting idea.

I'll try to do the math, but give me a while, because like I said, I dont remember shit from high school. To be useful, I still think you'd need a velocity exceeding 1000fps. And to retain most of this velocity, you'd need a fairly heavy pellet. Heavy pellet + high velocity = very painful. A .177 pellet gun pellet weighs 0.51 grams. A 6mm airsoft bb (about .243) weighs .20g-.36g generally. Therefore, an airsoft bb has less weight and more surface area. So it's pretty safe to assume that an airsoft bb has a greater drag coefficient. Even if you designed a better bb with less drag, at 1000fps, it would have to be very light to still be safe, and very light means it wont go very far. You just cannot design it so that you have the range while keeping it safe. I hope that makes some sense. To sum it up briefly:

-to get the range, you would need a high velocity and a heavy bb, this would make it very unsafe, as well as classify it as a real firearm
-to make it safe, you would need a low velocity, or a very light bb. Whichever one you choose, you will not get the range

Something to think about though. If it was possible to make a rifled airsoft gun that had range and was safe to play with, it would have been made a long time ago. There is a reason why all the companies have gone with hop up to get range. And yes, I know this thread is all about a rifled airsoft gun, but it is by no means safe to play with.

To get this to work, the bullet wouldnt be able to have any spin. Therefore you would lose all accuracy.

Alright, here we go. Who needs to do math when you can use an online ballistics calculator. Plus, this way I can use the drag coefficient as well.
http://members.airsoftcanada.com/gho...ballistics.jpg
-velocity 1000fps
-bullet weight 5 grains aka 0.33g, a common airsoft sniping bb weight
-range is in yards
-drop is in inches
-ToF = time of flight
-and energy is in ft lbs.

This is what I feel would be acceptable for gaming. At 100 yards, it has lost almost all energy, so this is about the maximum range. A 100 yard max range is decent for games. You would rarely shoot farther than that. At 100 yards, the drop is 50 inches. A high end Schmidt & Bender scope will give you a 56 MOA adjustment, so if zeroed properly, you would just be within the scopes range. But, I'm guessing most people wouldnt take the time to adjust the scope that many clicks. It wouldn't be that hard to just guesstimate 4 feet above the target and shoot. So, these ballistics sound pretty good, except...... muzzle energy is 11.2 ft lbs. which is over 15 joules. Just a little over field limits :-D 1.5-2 joules is a common outdoor limit. This would also make it a firearm, and would have to be licensed. It would also then be illegal to point at a person.

So there you go, to get an acceptable trajectory, the energy would just be way too high (and illegal).

If anyone needs clarification on anything, just ask.

Use google. The word you are asking us to spoonfeed you is: ballistics.

Thanks a million Ghost Snake, and I'll be your friend for life if you share the location of that ballistics calculator, I like the features it has! much fancier than the junk I've been using. (unless you took a screenshot of a purchased program). I'll give this address I've got on energy conversions, in exchange:
http://www.ajdesigner.com/phpenergyk...ation_mass.php

And I'd really really like to see the work on the BC calculation, what shape is it based on, etc?


"Ke=5.7joule, v=152meter/second, mass (m)=7.6146505031079 grain; 0.49342105263158gram"

I'd agree that safety is the top concern, and that velocity is limited, as is energy. But I believe there is some wiggle room that satisfies ballistics, safety and legality. Just need to find it!

For instance, retained velocity is based on the ballistic coefficient. It's possible you can get better retained velocity by increasing mass and reducing velocity proportionally. On top of that, there's form factor, the air resistance of the shape.



Also thank-you Myoga, I did understand better when you explained it.

Well you know, it was pretty hard to find. I mean, it was the first result when I typed in "ballistic calculator" on google. :wink:
http://www.handloads.com/calc/

When using the coefficient calculator, it doesnt accept bullet weights under 10 grains. So if you want the coefficient for a 5 grain bullet, do the calculation for a 10 grain, and then divide by 2. I did my calculations with a bullet diameter of .243 (roughly 6mm), weight of 10 grains, and I used HP as the bullet shape. This gave a coefficient of 0.021. My calculations were based on a 5 grain projectile, so 0.021 / 2 is 0.011. I used the HP shape because it was the closest to a pellet gun pellet.

A "blade bullet" though would be closer to the coefficient achieved by a boattail, maybe even a little better? Speaking of blade bullets, I wasnt able to find out for sure, but one source said that they were .34g. A blade bullet could potentially give you a coefficient somewhere around 0.025. But thats just a guess.

I spent over an hour trying to find a useable combination of bullet weight, velocity, etc. but I just couldnt get the energy low enough. I dont think a bullet weight under 0.34g (5 grains) would be stable. Leaving the coefficient and range out of it for a second. The max velocity a 0.34g bullet could be, before reaching the legal limit is 602fps. This wont give you very good range no matter what the coefficient. But keep in mind that even though it would be legal, there is no way you would want to play with that. If you are very careful about where you shoot a person, you could maybe get away with 2.5 joules, but even that is pushing it.

So, in conclusion, I personally dont think that rifled barrels and bullet shaped projectiles will ever be used in airsoft. And after using that calculator, I have also come to the conclusion that while the Asahi M700/M40 guns were cool, they were completely impractical for use in a game, simply because to be effective, the energy would have been way too high.

Another link that may help you is the fps/energy calculator on arnies. http://www.arniesairsoft.co.uk/?filn...s/fps_calc.htm

EDIT: Now that I actually look it up, 6mm is more like 0.236". Not that that would really affect the final results though.

well, it 'is' possible.

There is .22lr subsonic ammo that shoots at ~550fps at muzzle.
there is not as drastic a difference as you think there is between 425 (common bolt action limit in ontaio, and 550.

That said, good luck getting the gun to work this way, it would envolve lots of calculations and intensive engineering work.

No, its not possible. Fps isnt everything, far from it. So it shoots 550, big deal. What does the bullet weigh? A quick google search shows that subsonic .22 lr ammo weighs between 38 grains and 60 grains. Even at the lowest, 38 grains, that is still 33 joules of energy at 550 fps. Do you normally play at those kind of levels?

From what I remember (for clarification) the Asashi was never meant to skirmish.

It was for Japanese gun enthusiasts who (due to Japan's laws) cannot own the real rifle.

It was quite powerful, and even had aftermarket upgrades for the shells to get even more power (the shells were pumped up by a special hand pump to high pressure, to propel the rounds)

If I'm not totally mistaken, it was more for joy of ownership and for the pleasure of using a fully functional bolt action rifle that required no actual bullets.

It was a dead on replica, down to the last detail, and was so similar in function to a real rifle, that people were fitting .22 calibre barrels into them and using them to fire real ammunition.



Thus, the rifles were re-called and destroyed, with a few individuals who never bothered documenting their ownership (I think it had something to do with warranties), not being on the list for reposession.

So, there are a handful of the rifles floating around out there.

All this information came from some website that I can't remember the address for off the top of my head, but searching for "asahi rifle" and "holy grail" in the same search topic should find you the page :grin:

And yes, Ghost snake is right, FPS isn't everything, because if my 12 ft*lbs pellet rifle blasts holes in half inch plywood, 33 ft*lbs is going to wreck some tissue for sure.

For the record, the pellet rifle is slinging pellets at close to 700 FPS, which is somewhat lower than the .22 subsonic's 550 8)

Lots of factors. Mmm, factors.

Ghost Snake, thanks for the link, but eh-he I was tired and mis-read a couple of the boxes. Wishful thinking. I use the Eskimo.com stuff, it works, and what's missing I guesstimate and calculate.

But working with numbers for lighter and slower pellets, with a BC of only 0.15 you can get .30grn 500fps projectiles out to 50m with a max trajectory height of 4-5 inches at 25m, and still only dropping 12 inches by 70-75 meters. For reference, urban light posts seem to be placed about 50-60 meters apart on slow streets, 100 on faster streets. Of course, by 100m you're aiming 40 inches higher, but if the bullet goes straight and the wind is still, it just needs range estimation and skill to make hits.

For the blade bullet, I'm not sure about the design. I'd figured a design with 2 contact points, one on the head and one on the fins. Oh well, article says they were good to 100m.
http://www.airsoftplayers.com/m40a1/Ammo.jpg

Yes, fps isn't everything, and maybe the .22 subsonic was a bad example, but neither is bullet wheight. If bullet wheight had that much of an impact, how then can you explain bb guns, and pellet guns, that fire under 495, with quite decent accuracy, out to 100yds and more? And before you say it, yes, I know that steel bbs and lead pellets wheigh more than a bb, but if it can be engineered for them, it's not so far a strech of the imagination for the same to be done for airsoft bbs.

You're talking about a different point than he is.

You're arguing about flight trajectory and projectile stability.

He was merely trying to point out that muzzle energy and energy at impact are largely dependant on projectile mass. (with regards to safety and what projectile properties you would require to get a realistically useful trajectory without hop-up)

But even still, projectile mass plays a large part anyways, because of inertia. Even a well engineered shaped projectile that is lightweight is subject to being thrown off course or tumbling much faster than a hevier projectile **OF THE SAME SHAPE**, since it simply takes less to alter it's course.

** (i forgot to add this important point)

I think I might have something: A design that would weigh about 0.32 grams using the same material as 0.2gram BBs, with an estimated (calculated) ballistic coefficient of 0.148. Keeping speed to 410fps (125m/s) results in a muzzle energy level of 2.5 Joules. This ignores the possibility of minimum firing ranges, with higher energy levels (ie wherever pellet has only 2.5J).

Here's the ballistics I worked using the engine you showed (it has lower velocity limits, which is good). I set a zero at 50yards so one can aim COM and still hit only 6 inches high, to that point, for kicks.

http://i4.photobucket.com/albums/y14...ll/Ball2-1.jpg

And for comparison here's another calculator, but it has 500fps minimum:

Ballistic Coefficient: 0.148 G1 Bullet Weight: 5.00 gr
Diameter: 0.243 in
Muzzle Velocity: 500.0 ft/s Chronograph Distance: 10.0 ft

Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yds) (in) (moa) (in) (moa) (ft/s) (none) (ft•lbs) (s) (in) (moa)
0 0.0 *** 0.0 *** 501.5 0.449 2.8 0.000 0.0 ***
10 -0.6 -6.0 0.0 0.0 497.1 0.445 2.7 0.060 0.0 0.0
20 -2.7 -12.7 0.0 0.0 492.8 0.441 2.7 0.121 0.0 0.0
30 -6.1 -19.5 0.0 0.0 488.5 0.438 2.6 0.182 0.0 0.0
40 -11.0 -26.4 0.0 0.0 484.3 0.434 2.6 0.244 0.0 0.0
50 -17.4 -33.3 0.0 0.0 480.1 0.430 2.6 0.306 0.0 0.0
60 -25.4 -40.3 0.0 0.0 475.9 0.426 2.5 0.369 0.0 0.0
70 -34.8 -47.5 0.0 0.0 471.8 0.423 2.5 0.432 0.0 0.0
80 -45.8 -54.7 0.0 0.0 467.7 0.419 2.4 0.496 0.0 0.0
90 -58.4 -62.0 0.0 0.0 463.7 0.415 2.4 0.560 0.0 0.0
100 -72.6 -69.3 0.0 0.0 459.7 0.412 2.3 0.625 0.0 0.0
110 -88.5 -76.8 0.0 0.0 455.7 0.408 2.3 0.691 0.0 0.0
120 -106.0 -84.4 0.0 0.0 451.8 0.405 2.3 0.757 0.0 0.0
130 -125.3 -92.0 0.0 0.0 447.9 0.401 2.2 0.824 0.0 0.0
140 -146.3 -99.8 0.0 0.0 444.0 0.398 2.2 0.891 0.0 0.0
150 -169.0 -107.6 0.0 0.0 440.2 0.394 2.2 0.959 0.0 0.0


The bad news, moulds costs between $2000 and $8000, so I'm going to need to do a lot of my own experimenting and research before committing to have a mould made. Damn, at those prices the design would have to be perfected, for sure.

Hmmm, I dont know. Even though it has a max rise of 6 inches out to 50 yards, it has a drop of 54 inches at 100 yards. Out of curiosity's sake, how did you come up with a coefficient of 0.148? That seems very, very high. A 30 grain boattail, which is a rather efficient design, has a similar coefficient. Just wondering how a 5 grain could compare with a 30 grain boattail.

A paintball carries some 3 joules at the muzzle, and retains alot of it until impact.

Alot of that energy is dispersed when the paintball breaks (inelastic collision).
Paintballs still hurt quite a bit. Think about how much more they hurt when they bounce.

A solid pellet carrying 2.5 joules that will collide elastically with a person is going to hurt like hell, plus at only 6mm diameter, there's a much smaller surface area, which means all that force isn't going to be distributed as much.

So that one small area where it hits is going to be getting pounded.

I don't think you can achieve "accuracy at long range with a standard trajectory", and "can still safely shoot each other with it".

These two worlds seem unwilling to collide.

Thats the same conclusion I came to as well. Although I definitely dont discourage people from trying to prove me wrong. It would be awesome if someone could get it to work. Something to consider though, the bb/pellet doesnt have to be solid plastic. Maybe have the part that touches the rifling be plastic, but have everything else a soft rubber? I dont know.

cool. fun to think about anyways.

Calculated B/C by painstaking hand calculations of the volume of the designs, then assuming the same plastic used in 0.2g BBs, to arrive at a mass.

Then multiply the weight in grams by 1.422, divide that total by the square root of the diameter, and multiply by form factor. I used the worst form factor possible to be conservative, that of a plain jane wadcutter (flat-nose lead, ff 0.8). Lead doesn't refer to the density so much as the surface friction.