Poor Man's Chrono

The Poor Man's Chrono

This is a great thing for people who either don't have access to, or can't afford a real chrono.

Basically all you need is:

-.2 gram bbs
-a Coke can
-the gun you want to chrono
-you may want to wear some protective eyewear if you have a higher velocity gun

The Set-up:

Set up your coke can either top side up, or on it's side, depending on which test you do. (see below for tests)

Now posistion the tip of your gun's barrel an inch or two away from the spot on the can you wish to hit according to which test you are performing.


The Tests:

Test A: Muzzle Velocity: 290+ FPS
Set up your can top side up on a level platform. Then fire in the center or the side of the can. The bullet will go through one side, and bounce off the other and be left inside the can.

Test B: Muzzle Velocity: 340+ FPS
Set up your can the same as you did for Test A. This time, the bb should enter one side of the can, and clearly exit the other side.

Test C: Muzzle Velocity: 380+ FPS
Lay your can on it's side on a level surface, and position the tip of your gun's barrel an inch away from the center of the bottom of the can. The bullet should penetrate, and be left inside the can.

Test D: Muzzle Velocity: 450+ FPS
Set up your test jsut as you did in Test C, but this time aim your gun to the edge of the bottom of the can. It should end up inside the can, if it doesn't it didnt pass the test.

Test E: Muzzle Velocity: 470+ FPS
Lay your can on it's side on a level surface, and posistion the tip of your gun's barrel an inch away from the center of the top of the can. The bullet again must clearly penetrate and be left inside the can.

Test F: Muzzle Velocity: 500+ FPS
Set up your test jsut as you did for Test E, except this time aim for the top edge of the can. the bullet must penetrate or else it did not pass the test.

Hope this helps for those without a chrono, with these tests you can roughly find out your gun's velocity.

Very nice tests. I'll have to try these tests this weekend with my hi-capa 5.1 (black dragon w/extended barrel). I'm dying to know approximately what it's firing at I'm hoping around 350 with green gas!

Since I have a chrono in my posession and a few replica's that should atleast shoot for tests a,b,c and possibly d, I will let you know how accurate this really is.

Seabass_9000 wrote:

Since I have a chrono in my posession and a few replica's that should atleast shoot for tests a,b,c and possibly d, I will let you know how accurate this really is.

That'd be perfect. I'd love to hear the accuracy of these tests! Keep us updated. I've heard all sorts of methods of testing fps. It'd be nice to finally hear how precise some of them are.

Since I took the day off of work today (due to bad weather) I decided to go ahead and perform this experiment. These are my findings...
Apparently you must have to use a Coke can specifically for this test, since I didnt have any... I decided to try it with Pepsi and Big K cans, GO BIG K!!!!

All tests were performed with Excel .2 BB's and can tests were shot from approximately 1" (sorry for taking up a ton of space with this post).

Test A with KSC M9
[img][/img] [img][/img] [img][/img]
Just to show the difference between a powerful replica and a weaker one, I shot the M9 into the bottom of a can to show the difference compared to my AK and CA36...
[img][/img]


Test B with E1 AK47
[img][/img] [img][/img] [img][/img]

Test C with E1 AK47
[img][/img]
As you can see, the BB went through the bottom of the can and ended up left inside. Passes test C (with Pepsi can)

Intermission
[img][/img]


Test C with CA36c
[img][/img]
The CA managed to almost go through but the BB didnt make it all the way in. So according to the test it failed (with Pepsi can).


Now on to the chrono to see how close these are... (keep in mind I didnt use a Coke can, so results may not be the same and I will use a Coke can in the future just to see if the results differ)
KSC M9:
Not sure if it had to do with it being cold and green gas not cooperating, but it only shot a 263. So it should not have passed test A like it did.

E1 AK47 w/6.04mm tightbore and stock m110 spring:
[img][/img] Yep it is over 380fps... if you cant read it, it says 398. It also shot a 402fps but I didnt get a pic of that.

Now for the CA36c w/6.04mm tightbore, PDI 150% spring, etc... :
[img][/img]
So this is where I found a slight error in the test. As you can see the Chrono says 398fps as well... It also shot another 398 and a 395 after this, so it should have passed test C but it didnt. Maybe this has to do with the fact that I used a Pepsi can instead of a Coke can, but I would imagine it should have a similar result as the AK since they are practically shooting the same FPS. For some reason the AK went through the bottom of the can and the CA did not. I made sure this was a result that I would get several times over and it appears that my CA wont go through a can all the way but the AK does. It was a pretty interesting experiment though. Still not sure why the AK went through the can and the CA did not... ?

Then I had a little fun with the CA...
[img][/img]

Well. Very nice tests, and thanks for including pictures!! (they always make things more interesting). I don't know what to say though about the results. I thought Sentinel's tests seemed as though they could be valid, but obviously there are flaws with it (maybe the can makes the difference). I'm interested to know the difference between a coke can and a pepsi can, if any.

What about a different "poor man's chrono?" Anyone know any other methods?

Seabass, keep us updated on whether or not a Coke can makes the difference if you redo the test

ive herd that u have to take the tests with Coke cans only. this is because of the metal density in the Coke cans. i wold try to get your gun chronoed at a store if you can, because this test was righten about 10years ago and coke has def increased/decreased their metal content on their cans. a much more effective thing to do i when you get ur gun(or an upgrade) ask the supplier to put the chrono readings on a peace of paper before they ship it to you. i know that AirsoftSMITH will do this because they chrono all of their guns before they ship them(to see if they are firing/shooting at the right FPS). i cant vouch for any other suppliers, although i would think only the smaller stores would do this.

sticks

Yah like i said there will be around 20 fps intervals, the gap between the bottom of the can and the top of the can is pretty big, and i've heard some people who say their gun can shoot through the top but not the bottom. Not sure what causes this, maybe other manufacturers besides coke make the bottoms a little thicker so they can stack more ontop of eachother. Anyways this re assured me that my WELL shoots at around 470, when the box said it would shoot 410.

Precision Airsoft does that as well... I thought it was probably something to do with the can, but it still doesnt make much sense as to why the AK can shoot through the bottom of a Pepsi can when the CA36 cant and they are shooting about the same speed.

Anyways, I agree... just check it on a chrono like I used in the pics above or have the supplier send you a ticket like Sticks mentioned. It is way more accurate.


Question Sentinel, how far does your Well shoot? Does it seem like it has the range of a 470fps replica?

Yes it does, on the box it said its range was 25-30 meters lmao

Well thats what you want then. Good to hear that it shoots a bit harder than expected.

The box also had a lot of warnings labels written in Chinese, maybe theymessed up the conversion or something o.O

really kind of stupid, but I have never owned a chrono... so whenever I get a new gun and always ask somebody to shoot me with it lol
If I end up missing an ear or limping away in pain... i know I made the right decision

Ok I like having this poor mans chrono but when I shoot the top of the can on the edge the BB goes into the can. But when I shoot the top part on the top of the can it dents it and makes a hole but the BB doesn't penetrate. According to the test this should be the other way around. Thoughts?

My thought is... It isnt 100% accurate.

Not sure, it might just be your not using a coke can, or maybe its just the fact that aegs arent always as consistant as say a bolt action, because when i do these tests they work well for me.

The tests have to be done on a new can, or else it wont work the same, so maybe the reason you can penetrate the edge but not the center, is because youve already shot the can up. If not then i dont know.