g&p m870 spring downgrade

[Ross]

Has anyone owned one of these shotguns? Can the fps be changed? And if so what part would I need?

[Hectic]

it would be the spring but if its anything like my tri shot shotgun itll be a bitch to take apart and not break and a replacement spring wont be available so youll have to cut tue spring down.
if its a metal shotgun itll be easyer to tear down but again youll likely have to cut the spring and thats a lil hit or miss tryin to get the right fps.

[Thenooblord]

nah G&P 870 is dead simple to take apart, the spring however is another story, its long and narrow with tight coils, like some beefy 1911 recoil spring(I am not implying that a 1911 spring would work), i havent seen aftermarket springs for one, but you can just cut it

[Ross]

Bingo. Thanks guys.

[Hectic]

well least its an easy tear down, all tue plastic shotguns i got seem to be impossible to take apart without prying apart the body, gotta love metal shotguns lol.
so then tear it down cut off a coil on the spring reassemble chrony repeat tillyou hit yer target fps.
whats it shoot and whats yer target?

[Ross]

Originally Posted by Hectic

whats it shoot and whats yer target?

It shoots between 360 and 400. I'm still waiting for it in the mail so I don't know for sure. I've seen a video on youtube where ehobbyasia shoots it and it only shoots 300 ish and then another video where it shoots 380 so I don't know what the heck to expect. My target is 350 which is the local cqb limit.

[Ross]

Ok so I found that websites sell piston sets for this gun with two different spring options.

One option is 190% spring and the other is 150% spring. Obviously the 150% shoots lower

but I'd like to know if it's under 350 fps. Or maybe the stock gun is the 150 and this would be a waste of money. Does anyone know what 150%

actually means when it comes to fps? http://shop.ehobbyasia.com/g-p-m870-piston-set-a.html

[vink]

It's suppose to be APS spring compatible.

[Ross]

Originally Posted by vink

It's suppose to be APS spring compatible.

Yes, the shotgun is aps spring compatible. I've heard that a few times on different websites.

After googling "aps 7mm spring" all I have found are bearings and spring guides.

I've been told by retailers that this shotgun takes 7mm aps springs, but if I bought one, chances are it would be a bit too long and I'd have to cut it anyway because it would be most likely designed for a bolt action spring sniper. And by cutting it, I would be reducing the fps which defeats the purpose.

So instead of buying a mystery spring, I think my best bet is to buy the spring that was designed for this shotgun.

Not even G&P's website explains what 150% and 190% are relative to. So I'm just going to message every retailer that sell these piston sets and the first one that gets a reply will be the one that I buy from I guess.

[Hectic]

f the are listed like that 150% then they are likely 150% power up from stock.
now u have to figure if they wer alrdy pre upgraded for import with saya 150 or 190% spring or if they all come shooting 400ish. Most airsoft in Japan shoots sub 300 due to their laws and they make stuff "for export only" that shoots higher or stuff made in china is made for Japan or for north american markets at differet fps
to playit safe id get the 150% spring see what it chronos nd then choose wht spring to cut down for yer target fps

[Ross]

Thanks hectic. I think i may just take your advice. After much in depth research it is basically impossible to find these springs that offer a lower fps because they make them for snipers mostly. The maruzen ca870 takes the exact same spring and shoots 300 fps, which is perfect but finding a maruzen stock spring seems to be just as impossible as finding a sniper spring designed for under 350.

[Hectic]

that or if it actually does use aps type springs there are two kinds, there are 11mm ones that use a 7mm spring guide (i think that was wht u meant when lookin for a 7mm spring) or there are the 13mm springs that use the 9mm spring guide. If the 9mm guide will fit (it should cause its only the shaft thats bigget the base is the same) you have a wide range of lower power springs to choose from, tho i think that would start gettin expensive especially if you think the aps spring would still need to be cut cauee its too long.
http://www.x-fire.org/etop/bolt_sp_thicker.html
try checkin the length of the spring amd see if you can find the length of the aps springs to comfirm itll fit.

[Hectic]

if you go to redwolf you can get a aps spring guide with both 7 and 9mm fer 35 and springs are 20-25 youd want either the pdi 210 (400fps) or the pdi 240 (460 fps) causr youll have to cut a fair ammount off of it the 400 one may lose too much. So say both springs and guide for 100 bucks shipped plus taxes/duties.
id say just cut the stock spring one coil at a time till you hit 340-350 and save 120-150 bucks, but thats just me

[Kos-Mos]

All APS springs under 120% are "7mm" compatible.

also, a SP120 (LayLax SP120) will give you around 400 fps (in a BA). A SP100, should be sub 350.

[Ross]

An sp100 would be perfect but I haven't been able to find one. I have read that 9mm is too wide and does not fit into the shotgun so it has to be a 7mm. I'm just going to cut the stock spring. The spring included shoots 380 fps so I would hope I wouldn't have to cut too much off. I don't want the spring to bounce around in there.