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Staying in the FPS limit: how it's done
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TOPIC: Staying in the FPS limit: how it's done

Staying in the FPS limit: how it's done 6 years ago #1

  • Napster
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I know this came up before, so here it is. As a game admin, I go to great lengths to stay within FPS limits for all my guns to set a good example, yet stay as close to the limit as possible so my competitiveness doesn't have to suffer. I've listed some of the modifications I made specifically for this purpose, to achieve as close to the FPS limit as possible without going over.


So here it is, my latest "garage shooting" (remember to wear eye protection at all times when shooting airsoft guns, I had one richochet and hit my eyepro dead center where my eyeball would've been. For this testing session I used mixed .20g BBs from my "jar of BBs", a mixture of Excel .20g, G&G .20g, and Elite Force .20g, I believe all are 5.95mm +/- .01 diameter. In both guns a 11.1v 2200mah 25c discharge lipo fully charged was used with deans plugs. Sorry about the picture quality on some of these, I took them with my phone in a dimly lit garage.

First up, for general field use (FPS LIMIT 400): ICS MP5-SD6 shooting 398fps +/- 2. A cut M-120 and airseal mods put me right there after the heavy modifications I've already done and had done by other techs in the past. This is a high rate of fire build (still breaking in the new mags, they are starting to feed decently). Shot a 90 round midcap and every single shot chronoed 396-400 with one error shot giving me 65fps lol, we'll call that an error, although on my last test I got a single shot out of 2 mags hitting at 401 lol.


















Second up, for CQB use (FPS LIMIT 350): G&P M4A1 shooting 348fps +/- 2. Cut M-120 spring, changed cylinder, "swiss cheesed" piston. This is a high rate of fire build. I shot a full 140 round midcap and every single shot hit between 346 and 350.










The above is 348 if you can't see.



The above is 348 if you can't see.





Third up, for the Sniper class (FPS LIMIT 600): KWA SR-12/KM16, highly modified. Unfinished, Chrono testing and target shooting coming soon. Do I hear 598?








NOTE: Yes both guns are missing externals in these pics, I didn't assemble them fully because I was making adjustments constantly until I was happy withe the chrono results, so no point in fully assembling then taking apart again. I have more pics but it seems pointless to upload duplicate fps readings.

Also I'm not gonna chrono my M9 GBB pistol, because we don't chrono pistols unless they are full auto or are clearly shooting too hot for CQB (I.E. you can hear BBs break wind as they pass by you, not common for pistols without heavy modification). Except in extreme circumstances the 350fps rule does not apply for pistols, if yours happen to shoot just over no worries.
Sabin
US Navy Veteran



EWA | Webmaster / Admin
Team PRISM | C.O.
-Everyone's favorite computer nerd-
Last Edit: 6 years ago by Napster.
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Re: Staying in the FPS limit: how it's done 6 years ago #2

  • kool aid
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Just to clarify on the handguns thing, as a general rule, if it is a blow back, it is cqb safe. As not only does it drain fps and power on the blow back function, but most are designed in mind for cqb. And the only above cqb limit pistols I have seen are all non-blowback.
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Re: Staying in the FPS limit: how it's done 6 years ago #3

  • Napster
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Ok, the "how"

Honestly the M4 started by accident. I was gonna keep it stock but the piston stripped, so when I changed it I decided to put some 13:1 gears (super high speed), a new piston head, a new cylinder (I hate anything brass in airsoft, and besides I wanted to make sure my cylinder can support a 455mm tightbore, and a new M-120 spring in. I was aiming for 400 and got like 370 then I just cut the spring and decided to make it CQB, turns out I cut too much and it went down to 330, so I drilled holes in the piston to remove some material and added a small small spacer on the spring. For the fine tuning it comes down to the spring length, you can add a spacer to increase power or cut a coil off to reduce it. I posted videos of the airseal mods in the AEG section. Oh, for my spacer I grabbed the old stock G&P piston with the stripped teeth and used its inner diameter as a guide to cut a piece of hard rubber I found in the garage, then put a hole in for the spring guide and slid it on the spring guide and added a little silicone oil so the spring can rotate on it.

As for the MP5, I had Ghost cut the spring down as it was shooting over 400, before I started working on my own guns internally, and amazingly it just so happens to shoot perfectly with the airseal mods and barrel lockdown I did afterwards, the barrel lockdown was to secure the inner barrel to the silencer using a wrap of teflon tape covered by electric tape until it was a snug fit, then wedging a piece of plastic in between and cutting off the excess so the inner barrel doesn't move at all inside.


For a spacer you can use any hard material really, hopefully something that you can add or remove from easily. Cut it to the diameter of your piston and slide it on your spring guide. Don't forget to put some lube on it so the spring can rotate around it, I prefer to ever so slightly lube both ends of the spring for this purpose, although my piston head has a nice ball bearing.
Sabin
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EWA | Webmaster / Admin
Team PRISM | C.O.
-Everyone's favorite computer nerd-
Last Edit: 6 years ago by Napster.
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Re: Staying in the FPS limit: how it's done 6 years ago #4

  • Napster
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  • Have Fun! It's mandatory.
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kool aid wrote:
Just to clarify on the handguns thing, as a general rule, if it is a blow back, it is cqb safe. As not only does it drain fps and power on the blow back function, but most are designed in mind for cqb. And the only above cqb limit pistols I have seen are all non-blowback.


My KWA is already shooting at 360 with propane, in fact all KWA NS2s should be shooting over 350 with propane out of the box, with the extended barrel I'm putting in I expect another 10-20 fps increase, that's why I mentioned pistols, because I know someone's gonna say hey why don't you chrono that? I know it will shoot over 350, and we don't chrono them because the risk of injury is much lower than someone spraying you with full auto, besides I'm gonna start knifing every chance I get in CQB =D. Also for me the M9 will be for my sniper build, and I have a 50' medium engagement distance, but really once it gets to 100' and if they see me I'm either gonna book it or pull out the M9 and go at it, not gonna exchange fire at that range unless it's a single unlucky soul who strayed from the pack that for some reason I allowed to get up that close, so I wanted my M9 to be very effective at 100'.
Sabin
US Navy Veteran



EWA | Webmaster / Admin
Team PRISM | C.O.
-Everyone's favorite computer nerd-
Last Edit: 6 years ago by Napster.
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Re: Staying in the FPS limit: how it's done 6 years ago #5

  • Ghost
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Sweet stuff, cant wait to chrono my G36.
i just want to throw a carebear full of bricks and freedom at her and see what happens----Unknown
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Re: Staying in the FPS limit: how it's done 6 years ago #6

  • Flash
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He's giving me the M4 and a lot of magazines. He asked if I want it to shoot 400 or leave it at 350. What should I do?
PRISM
Little Napster
Last Edit: 6 years ago by Flash.
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