The BB too FPS Rule of thumb. Don't know what Gram to use, look here to find out

[BARRICADE]

Airsoft Technical Tips: AEG Springs      
Written by Fox     

Springs 
There are a lot of airsoft springs that are available in the market today. They are often coded or named with numbers that often leave buyers confused… Not to mention a each manufacturer have a different code for a spring for a given rating. Anyway here is a guide to help buyers to choose which spring to buy and an expected FPS output after the spring has settled (usually after a hundred cycles an airsoft spring settles and maintains a certain fps output till it eventually wears out)



Note: 

Accuracy troubleshooting in terms of BB weight

BB hits everything but the target

Cause:BB too light for the FPS rating

 
BB drop without reaching expected range

Cause:BB too heavy for your guns power rating

[Blaze]

Truthfully? if your going to kick over 400 fps? its better to start upgrading to .23's - .25's. My M4 is kicking 450 & i use .25's. If you have a good Tight Bore barrel, Hop-up, bucking & a knub to keep it stable? then yeah stay .20's & .23's.

others think difffrent im sure but thats just what use.

[nyghtbringer]

most people in this area use .25 i believe. usually the only ones that go higher are the snipers/dmrs. i didnt even know they made .23s. lol
.20 are rarely used by MS players i think.

[cloakndagger]

The 23s work for those of us with m16s that are shooting for accuracy aroud 390 fps to stay under dmr classpfication but have the range, prime case, my vfc m16 a1. most guys in ms dont hafta worry about that classification because it is not standard in state, but out of state it is. Most guys here shoot for 400 fps with 25s to be able to better deal with brush, which takes more joules. Once all this is said i should note, ive seen guns with longer barrels like a light bb, and shorties not process anything but heavies. My short explanation, which is apt to be wrong, goes like this

Lot of power+long barrel=heavy bb to use all the energy
little power+long barrel= light bb
Short barrel+lot of power= heavier bb
Short barrel+little power= go get a better gun cuz we dont cqb!
 this being the case, you can further confuse yourself by adding a tb barrel like so
tbb+lot of power+long barrel= light to med weight bb, because of the lack of leakage the bb will hit terminal stability at the muzzle and if properly hopped should fly straight

Every different thing you do from stock adds in another set of info tables which alas have not to my knowledge been comprehensively tabulated.

Is there a fluid dinamicist in tha house?

[echo214]

well, i know with my m16, a .2 flys about 200ft on a good shot when the hopup is working right, but it has a pretty big spread at that distance. a .25 will only fly about 140ft, but will have a much smaller spread. but i mine is shooting 410 fps with a high quality hopup, but a m4 length TBB

[Blaze]

Agreed with Cloak. Echo214: You should try a new piston head. most JG's come stock with a loose O-ring which dosent seal very good. They look like an awesome seal but if you can viz the piston flying back & forth hitting the Cylander head as fast as you roll wirh it? its not making much seal at all. not to mention the 7 holes in the piston head itself which allows air to excape thru the back of the piston & around the rear guide. I can probably make you a good sealing piston head in my box of wonders lol. If i can get it right you should clock in around 420-430 fps with .20's? maybe .23's. Also try a new knub in your hop-up chamber. that can effect the beckspin of your BB so buch where it can cause them to spread.

[echo214]

replacing it is what got it shooting 410 in the first place. it was 350 with .2s before. ask barricade how good that seal was...

[cloakndagger]

A few notes here
my calculations take a 100% air seal for granted

Check your airseal with the air nozzle on and extended, look for initial pressure, not what the constant hold is like.

Has anyone tried the x ring orings? I want to try one someday

Lube lube lube, whenever you change out a part go ahead and lube everything, and ust the right lube for the job!

nubs in the hopup can win or lose you the game, some guns dont work well with h nubs, some do, some want a squishy one some dont. Experiment is my advice here

[Blaze]

Has anyone tried the x ring orings? I want to try one someday

No but i really want to. I heard there really good but you never know unless you try them for yourself.

[madrule]

I would suggest that any AEG should start with at least .25s and try heavier BBs to see what gives the best range and accuracy that you desire. At around 450 FPS, .30 BBs would be where I would start and test different weights. Once you get to the higher FPS you will need to look hard at your bucking setup.

A guy that I used to play with swore by the X-rings. I believe that he was getting them from McMaster Carr. This should be the correct part # 4444-116, X-Ring Low Friction Seals

[cloakndagger]

Thank god someone who speaks my language!! Ill check mcmaster, though i have an account at grainger for our farm so i may check there too. Id say rarely around here do we see 450+ fps, but .25s are the standard. I always wondered why .20s sold better in al, but after playing mt doom i see that ranges are much closer than here because of the hills. While were talking o rings, anyone know the parts number for pistol mag gas fill orings?

[madrule]

Mag Fill O-Ring at McMaster Carr is a  Buna-N O-ring, part #: AS568A -002. Below are the measurements. Might be able to find them at a local Hardware store as well.

Inner Dia. 3/64"      Outer Dia. 9/64"
                0.042"                0.142"