M4 based sniper rifle only shooting 180fps???

[E_benoit]

I have a custom built M4 based Sniper Rifle that is not shooting over 180 fps. It has a systema drop in mech box (brand new), prometheus hopup, and Madbull 6.03mm hop up. I was hoping some one would have some ideas or the name of a good gun doc in northern ontario.

[CDN_Stalker]

Good chance a mismatch between the hop up unit and the mechbox's nozzle. What hop up unit in there and what spring is in the mechbox? I've seen mismatchings like that before but not that much of an fps drop.

[Crunchmeister]

How long is your barrel and does the mechbox have a ported cylinder?

[lupo]

Originally Posted by Crunchmeister

How long is your barrel and does the mechbox have a ported cylinder?

Crunch although that would affect the velocity it wouldnt be that much. As stated , most likely a nozzle mismatch. Could also be a bad hopup unit.

[Skladfin]

most likely you have a huge air leak somewhere, probably between the gearbox and hop up

[Crunchmeister]

Originally Posted by lupo

Crunch although that would affect the velocity it wouldnt be that much. As stated , most likely a nozzle mismatch. Could also be a bad hopup unit.

Agreed. I'm just offering another thing to check out. Installing a long-ass barrel with a ported cylinder could cause some issues. How much, I'm not sure, but I'm sure it would have a nice effect. And I also agree that on its own, it wouldn't cause that much of a drop in velocity.

I also tend to lean towards it being an air seal issue somewhere, and you guys are more than likely correct about it being the seal between the nozzle and hopup.

[AngelusNex]

Originally Posted by lupo

Crunch although that would affect the velocity it wouldnt be that much. As stated , most likely a nozzle mismatch. Could also be a bad hopup unit.

well if it has a ported cylinder that was accidentally installed backwards (port near nozzle) then it would have an effect.

[Crunchmeister]

I suspect that since it's a complete Systema mechbox, the cylinder is probably installed correctly. I brought up the point because he said it was a sniper rifle built from an M4. If he has a long, sniper barrel and an M4 mechbox, then the cylinder could be ported.

[Qlong]

Maybe the spring split into 2 and melded with each other, you never know.

[Renegade)]

Originally Posted by Qlong

Maybe the spring split into 2 and melded with each other, you never know.

Actually it was 3 splits, and can you beleive no one at Rawdon wanted to buy it?

If this was the case, the bb's would go 15 feet and plummit.. Sounds like an airseal issue as mentioned.

[E_benoit]

the mech box is not ported that i know of the barrel is 650mm long and the hopup is supposed to be a prometheus unit. hopefully i can figure this problem out cause right now i have a $2000 gun that can be outshot by canadian tire crapsoft.

[E_benoit]

After shortening the barrel and reinstalling the hopup it shoots perfectly.

[m102404]

Yeah!

[Shirley]

By any chance, may I see some pics of your rifle?

[maporms]

Airleaks... do the teflon mod.