A&K M249 spring replacement
 

I just purchased an A&K M249, but it's been upgraded to shoot 400 FPS. I need it to fire at 350 FPS, and the guy I bought it off of said all I need to do is replace the spring with a weaker one. However, I'm new to airsoft, and don't have a clue on what spring to buy or how to install it. I can search YouTube to find out how to do it, but would appreciate advice on what spring to buy. Thanks.

Please excuse my ignorance.
But.... why would you want to downgrade the SAW to shoot 350 fps?
Do you plan to use it indoors?

Saddly only one thing i can help you with, which is that the A&K 249's mech box allows you to just remove one screw or pin or something like that at the back so you can easily replace the spring without completely taking apart the mechbox.

I'm participating in border wars and the limit is 350 since there's going to be a lot of CQB stuff indoors, I'm definatly putting the stronger spring in after. I just need to know what spring to buy, I figured out how to replace the spring from YouTube, just need to know what spring I need

http://www.airsoftparts.ca/store2/in...ex&cPath=66_82

Either Modify S90 or S100. S90 will likely be comfortably under 350fps, S100 might be slightly over (or not, depending on airseal). You could always buy both, they're not that expensive.

http://www.arniesairsoft.co.uk/revie...uct/797/cat/16

Here's a great walk through and reveiw on the A&K 249 including pics of the spring swap and more.

And here is the spring replacement guide

YouTube - A&K M249 Minimi Spring change in less than 5 mins

Go with an 90. it'll probably be around 315fpsish but you only want it for that game and it's mostly cqb so 315ish isn't bad.

The spring can be swapped in about 2 minutes with no tools as you can see in that video.at least with mine, the pin is easy to remove by hand. Seemed in the video he was having some trouble with his.

And just FYI, that gun shoots 400 stock. It wasn't upgraded to shoot at that velocity.