Easy way to reduce velocity?

[sj_asc]

Re: Easy way to reduce velocity?

How about using an ICS Split Piece as a base? That way you could have a shorter upper with a lighter spring for CQB and swap it out for a second top half with a longer barrel and harder spring.

[jonny lovegrove]

Re: Easy way to reduce velocity?

you still have the issue then of full auto / non semi restricted higher powered AEG.

[Figjam]

Re: Easy way to reduce velocity?

I'm surprised to hear the concerns about semi lock off. I've not paid much attention to semi auto DMRs myself - 425-450 is too long for Dick, too short for Richard IMO - but every locked-to-semi gun I've seen has done it with a bolt physically screwed in front of the selector switch, which can be removed if needs be to clear a locked up gearbox with a short burst of full auto with the mag out. If that system isn't allowed how do players deal with Semi-lockup?

[dave38x]

Re: Easy way to reduce velocity?

By removing the mag and punching the forward assist on their ics gat, releasing the arl - you could easily mod a dmr to do the same.

[North West Outpost]

Re: Easy way to reduce velocity?

I'm surprised to hear the concerns about semi lock off. I've not paid much attention to semi auto DMRs myself - 425-450 is too long for Dick, too short for Richard IMO - but every locked-to-semi gun I've seen has done it with a bolt physically screwed in front of the selector switch, which can be removed if needs be to clear a locked up gearbox with a short burst of full auto with the mag out. If that system isn't allowed how do players deal with Semi-lockup?

Neo magnet ultra torque motor, large 11.1 and fet protection. That should do it.


Back to original idea. Have you considered using the same gear box, but have an R hop in the longer barrel?

[Sir Stephen]

Re: Easy way to reduce velocity?

easyest way to do it is to set up the gearbox to produce the maximum fps with the longest inner barrel you will be using.
so its you want a dmd/carbine, set the fps with the dmr upper, then build your carbine upper to provide a suitable fps reduction (a rough guid is 2-3" is about 10fps, at least thats what i have found in my spectres).
i use this system and it works great, each upper is set up correctly, and the only thing that is causing the fps loss is the shorter barrel, not air leaks, or custom cylinders etc, so i keep my consistency with each upper.

[a_flea]

Re: Easy way to reduce velocity?

10fps is a completely pointless variance, the OP (who incidentally is probably regretting this thread as he hasn't come back) would only want different fps to stay within certain site rules, for instance:
Longer upper = 370-400fps semi only
Shorter upper = 320-350fps
You are talking about trying to get around 50fps variance out of just a barrel and hop; which is just about possible, but retaining useable accuracy will be hard (probably more likely to be achievable by accident). Or a split gearbox design which is more of a pain and slightly limiting, not to mention the semi-only issue.

But the only real solution is two guns; its simple, quick, and actually more flexible.

[dave38x]

How is accuracy lost if both uppers are optimised to work wth the lower?

Sent from outer space

[Blackwood]

Re: Easy way to reduce velocity?

Neo magnet ultra torque motor, large 11.1 and fet protection. That should do it.


Back to original idea. Have you considered using the same gear box, but have an R hop in the longer barrel?

What exactly is an R hop,, I had a quick look and it looks like a rubber that just goes in the window of the barrel rather than wrapping around the entire thing. And how would that affect FPS?

[Bachelarius]

Re: Easy way to reduce velocity?

Yeah, best bet is to do the research on it, there's entire threads on the concept and the inventor's/manufacturer's site is here, which has stuff like installation instructions and such like. It doesn't obstruct the path of a bb in the barrel as a regular hop, so higher fps.

But, really, don't get hung up on fps. It's just a number and doesn't affect accuracy as much as, say, barrel quality or hop unit quality or air seal. They are all factors, and it makes sense to do some research on accuracy (e.g. this thread, as an example - not all the stuff there is valid, but the way he thinks and the principles behind his theories are fantastic - exactly how DMR builders should always think)

[Sir Stephen]

Re: Easy way to reduce velocity?

thought i might as well do a test since i have nothing better to do.

20.5" standard bore barrel, shs hop unit, random rubber and nub. 347-350 fps (and very consistent also i might add, surprising as i only chucked a load of spares together)
7.5" standard bore barrel, prowin hop unit, random rubber and element H nub, 310-315fps.

so a 13" barrel length difference gives a 30fps difference with my set up.

with 2 finely tuned hop/barrel sets, the op may be able to get a CQB upper set at 350, with a carbine/rifle length upper at 380, witch is a fair fps for a dmr.

would be a damn sight easier to just buy 2 rifles though, have to agree.