Two guns need a tweak - can you help?

[Panoptes]

I have a CA M249 and G3KA4 (FS51 internals) which need uprating:

M249 (w/Prometheus Tightbore):

260 FPS
0.77 Joules

G3KA4 (Standard Barrel)

277 FPS
0.89 Joules

Readings with Madbull v2 Chrono. (FPS are measured with .25 BBs by the way).

I have Guarder M100 and M110 springs on the way plus a 407mm Prommy barrel for the G3KA4.

Which springs do you suggest I use in each? I'm aiming for around 1.2 Joules for the M249 and 1 Joule on the nose for the G3KA4.

[sniperiain]

Re: Two guns need a tweak - can you help?

well dont forget your using .25s every site chronos with .20s. if i were you get a meassurement using .20s and we can see from there

[Panoptes]

Re: Two guns need a tweak - can you help?

Stuff packed away now. Must be a cross-reference/conversion chart somewhere?...

I'm not fussed about the 1J limit and the Madbull can chrono on any weight btw.

Don't the SP100, SP110 work on percentage increases?

[sniperiain]

Re: Two guns need a tweak - can you help?

oh rigth well apparently the systema m100s are supposed to kick out 340 is fps on .20s?

[The Keeper of Secrets]

Re: Two guns need a tweak - can you help?

Anything from 340-360 I think. I had them doing 340 and 355 in two stock marui gearboxes.

[Panoptes]

Re: Two guns need a tweak - can you help?

Thanks.

I'm estimating that the tightbore and M100 on the G3KA4 should give 10% each - bring it to around 1.6Joules. The M110 for the M249; bringing it to around 0.93 Joules. Anyone concur with this?

Something else is adrift on the M249 anyway, hence the low energy rating - it's been suggested that I get a new air seal nozzle but I really don't want to open up the gearbox.

Any thoughts.

[The Keeper of Secrets]

Re: Two guns need a tweak - can you help?

But it's a really easy gearbox to open up! Comes straight out the reciever, take out the hot swap spring without having to have everything fly out everywhere.

Anyway, an M100 plus a thighbore will take you to about 355-370, roughly.

[Panoptes]

Re: Two guns need a tweak - can you help?

But it's a really easy gearbox to open up! Comes straight out the reciever, take out the hot swap spring without having to have everything fly out everywhere.

I don't have to take the receiver apart? Does it just lift out?

Anyway, an M100 plus a thighbore will take you to about 355-370, roughly.

The G3? On .25s?

[The Keeper of Secrets]

Re: Two guns need a tweak - can you help?

On .2s. Sorry.

And you release tha barrel, the take out two screws on the receiver. Then slide out the charging handle (there may be another screw blocking it, take it out). The gearbox should then just slide up out of the receiver. Be careful and watch the wiring.

That's all IF it's EXACTLY the same as the A&K, which I'm 95.72386% sure it is

[Will_0]

Re: Two guns need a tweak - can you help?

You have to take off the front plastic grip as well in order to get the charging handle off otherwise it obstructs it. It is a VERY easy gearbox to work on though, one of the easiest I've done.

[Panoptes]

Re: Two guns need a tweak - can you help?

Thanks.

Why do think it's so low as it is (remembering the figures are for .25s and given that it's already got a tightbore).

[The Keeper of Secrets]

Re: Two guns need a tweak - can you help?

Could be a bad hop unit, or an airseal problem.

[Panoptes]

Re: Two guns need a tweak - can you help?

Hmm. How can I tell?

[The Keeper of Secrets]

Re: Two guns need a tweak - can you help?

Open the gearbox, then take pout your piston and cylinder assembly. Hold your finger over the nozzle and push the piston down the cylinder. A good airseal should offer enough resistance to stop you. If you can psh it all the way down, then clean everything, and just roll the O ring around your fingers, stretching it (gently), and working new grease into it. Works for me.

[Panoptes]

Re: Two guns need a tweak - can you help?

Well... stripped her down today. Re-greased the cylinder and checked seals etc but it's still only around .80 Joules and this is with a tightbore barrel and an M110 spring... Something's wrong but I can't see what.

Warranty repair?