GR25 Dmr

[Scottybot_2000]

I've just bought a Gr25 and It shoots Kind of slow for a semi - only at arounf 320 to 335 and my local site allows 450 fps for semi only guns. I only use 0.2's and need to get this gun just under 450 fps what spring do you guys and gals suggest?

 

[Russe11]

In the 'app' tab there are tools to work things like this out. M130 would be best bet, M140 might be too strong.

[Airsoft_Mr B]

The number is the velocity it should achieve with that spring. So as an example, an M90 = 90 m/s or ~300 FPS.

Taking other factors into account (air seal etc) the actual FPS you're getting will vary.

Just saying you really need to use heavier BBs than 0.20s in a DMR. (But need to chrono with .20s)

[jcheeseright]

yeah, if you boost it to 450fps, don't shoot .20g BBs at 450fps, you won't get any extra range and accuracy will be all over the place. at 450fps I'd be looking at .36g or .40g for maximum range and accuracy.

[TacMaster]

You will need to do some extensive internal work to get it firing between 425-450 FPS. This will include changing:

• Motor (for a high torque one to pull a stronger spring)
• A new spring- as said before, an M120 is your best bet
• Gears may need looking at or changing. Angle of Engagement correction is a must
• Piston and piston head in case the new gears strip the piston's teeth. The new piston must be a softer material than the gears. The piston head will improve airflow
• Air nozzle- again, improving seals and airflow
• PTFE tape wrap around the hop rubber's end- will improve the air seal
• A Gate Nano/Pico AB MOSFET or any other decent Fet to improve trigger response
• Hop unit will have to be exchanged if it's shite or have a new rubber and nub in. R-Hop mods are popular and mine gives me good results in my M27, but they're fiddly to set up perfectly
• A TBB. None of this MadBull crap for DMRs, you'll need a Prometheus barrel to get the best from it
• Wiring the rifle to Deans connectors for LiPo batteries is a must. Deans connectors have the largest contacts between battery and gun, meaning there is less resistance compared to Tamiya connectors which have a much smaller contact area.
• LiPo batteries are a must in my opinion. You can't get the best out of your gun's trigger response without a LiPo, and if you've installed a MOSFET you will get the best out of it.

 

A while back I was looking at converting a CYMA MP5 to DMR standard. All of the parts cost about £100 in total, however that wasn't including a few parts which the stock components had the same performance as (IE the motor- CYMA's motors are pretty decent).

My current DMR wasn't done by myself, I bought it for a steal on a 2nd hand FB page, and it's had a lot more done internally than my barebones MP5 DMR project. IDK what the total upgrade cost was, but I bought it for around £320 (the base gun was £450, £500 in places) and a LOT of internal upgrades were done to it (including all of the above and some more). It's performing brilliantly, and the only work needed doing to it is external bits and pieces I haven't got round to buying.

[Mr Monkey Nuts]

[yoda voice] 450fps and scope, a DMR does not make; young padawan!