Decrease FPS

b.samriey

b.samriey

Well-Known Member
28 okt 2015
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Hi guys!

I got quastion here and i would like to benefit from your experience please, recently i got my M4 RIS and the manual puls many videos on internet it says this gun has 380~390 FPS which is design for outdoor activities, this means i won't be able to join the closer Skirm field (Rslairsoft.nl) locate at Assendelft which is require max 360 FPS to be accepted, but at the same time the wibsite says Alle airsoftapparaten: max. 500 FPS. So i didn't relly understand if these 360 FPS for CQBs only or for whole gameplay if does then these 500 FPS for what style or gameplay? 

the link: http://www.rslairsoft.nl/airsoft/spelregels  

Back to the FPS downgrade, if i would like to decrease my FPS with out open my gearbox and replacing my stock spring what do you suggest me guys?

1. Pull the trigger just half and keeping the spring compressed overnight? anyone tried this before!

2. Replace my gun with short barrel, if does what is the best short barrel you recommend?

3. Shooting more than 2000 BB's will lower my spring FPS at the end? 

Thank you in advance!
 
Hi Samriey,


360 FPS is the global limit to all full-auto shooting replicas and pistol-replicas.

The exception is (bolt-action) sniper-replicas. These are allowed to shoot up to 500 FPS max.


Pulling the trigger just half? Depending what you play with (gas or AEG), pulling your trigger is only a ON/OFF signal given to the rest of your internals. So pulling it half would mean no signal, until pulled far enough to give ON signal and turn gears, etc etc.


Short barrel might effect the FPS, but I'm not sure how much. Could be a 10 to 20 FPS change in effect?


Shooting more than 2000 BBs might effect the strain on the spring, but I'm not sure if it will lower the FPS by more than 20 or 50 FPS. 


I'm sure someone can add information regarding this subject, but I hope I've helped some.


 
 
The fps rules are 360 for full auto replicas, dmr (assault replicas with singleshot only) are 450fps sometimes a 2 sec delay is needed. And bolt action sniper replicas are 500fps.
 
None of the options your are mentioning, will decrease the FPS enough.


Not even a combination of the options you are giving, will be decreasing your FPS to < 360.


So I'm afraid you have to open it up :(
 
@Stey It's AEG, what i mean by pulling the trigger just half (give the order to the trigger to compress the spring) then instantaneously remove my finger or disconnect the battery here the cylinder will keep compressing the spring and won't won't release until you do so, But this also will put my gearbox in unnecessary pressure but for short time it's ok, however that why i've been asking if somebody ever tried before..

Well the only think i need 30 FPS drop if shooting 2000 BB's or short barrel will achieve this end this would be fantastic to me, because my M4 shooting 390~380 FPS - 30 = i got 360 FPS without opening or replacing any original setup.

@Sander it would be very awesome if they allowed full auto replicas 450 FPS gameplay can you imagine that man! 

@Eviltwin-NL dude don't tell me, i can't imagine this nightmare like open the gearbox and mess with it, not to mention i have to remember all the little bits and the actual putting it back together that if i didn't brokning or lost something wihle i'm work on it, it's brand new still with warranty, last night i've been trying to open the flashhider and then it got a little scratch.. honestly i got sick haha it's KWA U.S Manufacturer
FJeuv6g.jpg
 
What you might try, is considering a widebore barrel  (6,2 or 6,23). Because the diameter of barrel increases, the "loss" of air between the BB & the barrel also increases.  Coming from a 6.08 stock barrel, it gives you an esitmated  loss in of > 30 FPS     So sthat will get you on the safe side of the 360 limit... If it doenst, compressing the spring will do the last bit.


The only down side on this solution: For a widebore barrel, they usually place a bigger  (full) cillinder.  So I'm not %100 if it works. But I believe it will.


I think you will get great results if you use the following combination (trying it in my M4 right now):


--------------------------------------------------------------------------------------------------


Modify Flathop:


http://www.airsoft-heaven.nl/index.php/parts/hop-up/modify-baton-ryusoku-flat-hopup-bucking-voor-airsoft-aegs-soft.html


Prometheus Delta strike barrel 363 mm   6,2 diameter


http://www.airsoft-heaven.nl/index.php/parts/inner-barrel/6-20-widebore/prometheus-6-20-delta-strike-widebore-precision-barrel.html


 
 
Oke, I just found out, that the delta strike doenst have the cut in the barrel, where the bucking should slide in to. So you can buy the combination I posted in the previous post. But you need to do some sanding, to get it to fit :(
 
Eviltwin-NL i really appreciate evry single word you edit here, my M4 inner barrel length 395 mm and diameter 6.05 mm so do you believe if i replace it with 6.08 barrel will help to drop my FPS to 360? if does what is the best and most accurate barrel you advise me for? regarding to Hop up unit i won't to replace the stock Hop Up Bucking because KWA add high-performance Hop Up with zero air lost plus fins produce consistent performers for very shot so i don't want to sacrifice it..

i love to hear back from you and Merry Christmas evry one! 

BIuvD29.png
 
About the barrel, some barrels has cut so if the barrel diameter can drop my FPS then advise me for what mark you recommend. 
 
Bas, no offense but why dont you Just replace the spring. Thats way more easy and cheaper.
I can help you out with it. I done tons of downgrades so its no problem for me.
I live in hoorn thats almost around the corner :p
 
I doubt that a 6,08 mm will decrease the FPS enough. But there is only 1 way to find out ;)

You can try an El cheapo stock 6.08 barrel. And measure the FPS. If it ends up at 370, then you probably can get it down to < 360 with a compressed spring / 2000 BBs. IF that works you can buy a more expensive barrel later.

You can always ask around if some 1 haves a spare 6.08 barrel you can try. Unfortunately I only have 6.04 stock barrels. So I can't help you out on that one.

I haven't found any other widebore barrels, besides the orga and prommy delta (6,23 & 6.20 ) . So I hope, that someone else can help you with finding an other barrel width > 6.08

Mery Christmas and Happy barrel hunting ;)
 
Sander That is very kind from you man! well frankly I've never opened any Airsoft gearbox before however, how can we manage that I am in Heemskerk as you know and carrying my gun even with bag through public transportation for no events just not good idea.. so if you got Chronograph and never mind to vist me (and i will cover your transport paid) and see what we got here and deside on, left or right there is some cold beer in the fridge want to be celebrated, so why don't you come ove and it's good chance to know all of you guys! at the end if my FPS higher than 360 then i will order a new spring and will change it later if not the beers already on the table and will get good time.


Eviltwin-NL I alrady warm my gun with 2400 BB's no carton box left in my home, however thank you very much to all your concern and replies, will see what we can manage (me and sander)..

vCquhep.jpg


 
 
Yeah i could Just Come over with chrono that is no problem for me. That will be after xmas ofcourse ;-)
Also i suppose you got some tools? If not no problem i can take them with me.
 
Excellent, i got all what you need screwdrivers, Allen keys, pliers,silicone oil..etc only if there is something (very special to gearbox or airsoft gun) just let me know to prepare it or you may bring it with you,i didn't buy a new spring if i sould advise me for the best one and inform me when you're ready, take good care man and see you soon! 

BTW i was reading the KWA M4 RIS user manual and i found that indeed the spring will break-in period through shooting minimum of 2000 rounds, so perhaps my spring right now about 360 FPS or even low, but will check that later together..

QWCWWFY.png
 
I will bring a chrono so we can check what fps it is. I will also bring a New guarder sp100 spring with me so we can change it if it appears to be shooting Hot. Further there is nothing special about a gearbox so you got all the tools ;-)
I will contact you after xmass in youre inbox. Have a nice xmass by the way. :-D
 
Just loved to share the last result of Can Chronograph Test now my gun definitely shot under 350 FPS !


7GCk1CJ.jpg
 
Nothing just try to shot 2000 BB's or even 1500 and your spring will compress and your FPS will decrease at lest 30~40 FPS, my gun came with 391 FPS now you can see the result. If you're going to try this (DO NOT) shot all 2000 BB's at one time or your motor will get over heat and stop working, try to shot 500 BB's per day and you will see the difference.

Good luck 
 
That looks good, still in need of a chrono or do you buy the result ;-)
 
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