Jump to content


Tight recoil spring and fps

Mp7 Recoil Spring Higher Fps Increase Propane Rhop

  • Please log in to reply
17 replies to this topic

#1 905taylor905

905taylor905

    Newbie

  • Members
  • Pip
  • 10 posts
  • Country:

Posted 14 July 2014 - 07:18 AM

I have done research on this topic and it turns out a recoil spring would not increase fps.
But I was shooting 405 with my mp7 and after tightening my recoil spring I am now shooting 500.
This is very confusing to me as I have no idea how this could be increasing fps.
I used tubing from work to r-hop it and punched a hole in my bucking right at the divot to ensure the plunger fit in the hole and applied hop directly to the r-hop patch with no side to side deviation.  (I guess not r hop.  More a custom hop patch)
I was expecting a drop in fps by a little due to the hole in the bucking but to my dismay it was a ridiculous 500 fps.   The accuracy and range are extremely good.  Far better then it has ever shot before.  But this fps is way over field limits and needs to be fixed.   All of these hop up changes were working at 400 fps and was accurate and all.   But once I tightened that recoil spring it was 500 fps.    I'm confused and would like a little advice.  
I have weakened the recoil spring and have yet to test it but I will post my results today after I'm able to test it.   Any ideas on what's going on?
I use propane and always have.  
Thanks in advance.

#2 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 14 July 2014 - 08:25 AM

How does the bolt act? Also was the first shot you took at 500 or did it jump to 500 afterwards?

#3 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 14 July 2014 - 08:29 AM

Just thought of something, it might be possible that with the R hop installed it's creating a greater seal than it does with just the stock bucking. Causing more gas to release to move the bb. I do know that I tried a shorter bucking once and it didn't create a good enough seal to move the bb much at all, so I'm thinking yours is getting a greater seal. Just a thought though

#4 905taylor905

905taylor905

    Newbie

  • Members
  • Pip
  • 10 posts
  • Country:

Posted 14 July 2014 - 08:33 AM

First shot was 500.  It slowly dropped as the mag drained.  But was still around 450 on last shot of the mag.  
As for the bolt.  I don't really know.  I did not see the bolt but it loads the next bb no problem, no feeding issues or anything.
My guess was the fact it took longer to cycle the bolt back, the air nozzle was staying in the bucking a bit longer giving that extra gas into the barrel.   Makes sense in my head, and I'm not sure why people everywhere say that recoil springs have no affect with fps.    But I know just because it seems logical in my head doesn't make it fact.   But I'm still lost.  

Thanks for the quick response.

EDIT:
That doesn't seem to far fetched at all, but as I stated, I had the r hop installed before I tightened the recoil spring and the Fps then was 400.  So I do not think that is the problem.

Edited by 905taylor905, 14 July 2014 - 08:35 AM.


#5 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 14 July 2014 - 08:42 AM

Yeah I should have read the post more carefully, my thought is with the recoil spring tighter it's forcing the bolt more forward causing a greater seal. Pushing the cylinder nozzle farther into the bucking.

#6 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 14 July 2014 - 08:47 AM

I mean the cylinder nozzle has two springs on the sides that clip to a little metal bar at the end of the bolt, the gas is released into the gas port on the nozzle and goes around the valve inside, then into the barrel. My thinking is because of the recoil spring itself putting more force moving the bolt forward it's jamming the bolt and moving the nozzle more forward.

Side note... I'm really bad at explaining things so just bare with me lol

#7 905taylor905

905taylor905

    Newbie

  • Members
  • Pip
  • 10 posts
  • Country:

Posted 14 July 2014 - 08:55 AM

No.   That makes perfect sense.     I never thought of it like that.  Almost what my thoughts were...
I'm going to test it tonight at a game I'm going to.    If its fixed we may have stumbled upon something here with recoil springs causing better compression as well... Equaling higher fps.

Thanks a lot chaos.

#8 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 14 July 2014 - 09:21 AM

If we are right the only problem is it'll wear the bolt out much faster.

I'm trying to figure out how to suppress the mp7 but so far the gas needed to compress the bolt back is to great and loud.....

Edited by ChaosMP7, 14 July 2014 - 09:25 AM.


#9 905taylor905

905taylor905

    Newbie

  • Members
  • Pip
  • 10 posts
  • Country:

Posted 14 July 2014 - 10:01 AM

Well I'm an AEG guy mostly.      Great with the v2 gearbox but when it comes to gbbs I'm pretty much new to the whole thing.
No idea how to silence a gbb.   Would imagine it's tough.

#10 BLATEY

BLATEY

    Enthusiast

  • Members
  • PipPip
  • 190 posts
  • Gender:Male
  • Location:Iowa City, Iowa
  • Interests:Keepin' it Real.
  • Country:

Posted 14 July 2014 - 12:54 PM

I'm pretty sure its illegal to silence an airsoft gun, but hey who cares!

#11 StealthTaskForce

StealthTaskForce

    Enthusiast

  • Members
  • PipPip
  • 189 posts
  • Gender:Male
  • Location:Tampa
  • Interests:Airsoft, Paintball, Sports, My girlfriend, Knives and Real Steel
  • Country:

Posted 14 July 2014 - 03:00 PM

View PostBLATEY, on 14 July 2014 - 12:54 PM, said:

I'm pretty sure its illegal to silence an airsoft gun, but hey who cares!
Blatey is right. It is illegal, and I think any discussion on the topic of silencing one gets the thread closed.. So how bout back to the topic? Lol

#12 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 14 July 2014 - 03:43 PM

Really? Hmm I'll have to look into this more then, I've seen store bought surrpessers. I think you can buy a Permit to use them, Ive heard anyway. Also if we use this logic we should all go to jail or have our guns taken for not having orange tips lol. But I'm sorry I'll stop my talk.

#13 StealthTaskForce

StealthTaskForce

    Enthusiast

  • Members
  • PipPip
  • 189 posts
  • Gender:Male
  • Location:Tampa
  • Interests:Airsoft, Paintball, Sports, My girlfriend, Knives and Real Steel
  • Country:

Posted 14 July 2014 - 04:48 PM

No, orange tips are only needed for sale from companies. And permits can be issued to use suppressors for real steels. But on airsoft guns it's illegal to dampen the sound in any way. Which is why discussion of it is forbidden here


Sent from my iPhone using Tapatalk

#14 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 14 July 2014 - 05:34 PM

I truly am sorry, please forgive my rudeness.

#15 Pyro_Buster

Pyro_Buster

    Enthusiast

  • Members
  • PipPip
  • 120 posts
  • Gender:Male
  • Location:California
  • Country:

Posted 14 July 2014 - 06:44 PM

In a lot of countries, suppressors are required if you own a firearm. Which is why I think it's weird we have to have permits.

#16 BLATEY

BLATEY

    Enthusiast

  • Members
  • PipPip
  • 190 posts
  • Gender:Male
  • Location:Iowa City, Iowa
  • Interests:Keepin' it Real.
  • Country:

Posted 14 July 2014 - 07:09 PM

Don't wake your neighbors!

#17 905taylor905

905taylor905

    Newbie

  • Members
  • Pip
  • 10 posts
  • Country:

Posted 18 July 2014 - 10:17 AM

Wow.  This really spun off in the wrong direction. (No worries)   Lets just get it back on topic...

I've tested the mp7 with the weaker recoil spring and there was a small 50 fps change.  Now I'm really confused.
It was 365 with .28 which is around 450 fps with .2s.  Still too powerful for my field.  I would really like to try a low power bolt to see if that gets me in the proper fps but unfortunately haven't been able to get one ordered yet.

I've purchased the ra-tech hop up bucking and am going to install this right now to see if there is any fps change.    
I will remove my r hop patch and see where that gets me.
If it doesn't fix the problem I will re install the r hop patch exactly how it was and go with the low power bolt once its available to me.
Any other advice on the bolt itself would be very helpful.

EDIT:

Now ive noticed There are 4 screws on the bolt... 2 on the left and 2 on the right side of the bolt.   I just noticed when going to install the ra tech bucking they were very loose, so I tightened them all and everything is still moving really smooth.   I'd hate to think something like this could have been my problem.   But I will hold off on the bucking swap until I can have it chronoed one last time with the bolt screws tightened.  
Thanks for any help in advance.

Edited by 905taylor905, 18 July 2014 - 10:20 AM.


#18 ChaosMP7

ChaosMP7

    Newbie

  • Members
  • Pip
  • 26 posts
  • Country:

Posted 18 July 2014 - 11:51 AM

The 4 screws you are talking about stay loose. Mine are right now even after I snugged them down.  

Ok so let's see, with the stock recoil spring in it shoots 450 now instead of 500? Let me ask you this, when you redid the recoil spring you didn't oil it a lot did you? I do think we are right about what we thought before but I also am thinking the bucking might be swelling. Do you have another stock bucking? If so you can compare the two and see the difference.





Also tagged with one or more of these keywords: Mp7, Recoil, Spring, Higher, Fps, Increase, Propane, Rhop

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users