To short stroke, or not to short stroke?

[Antny]

So basically my M4 is shooting a little hot (380 be exact). Now i'm going to be rewiring it next week and installing an active brake mosfet so i was wondering what people opinions are on short stroking. I could either replace the spring to bring the fps down, or short stroke 3 (maybe 4) teeth. I play CQB only with the M4 so i want the best trigger response rather than flat out rof. It already has 20-25 rps on a 7.4v lipo, and that's fine by me, although i am aware short stroking will increase this some what. Will be my first short stroking so wanted to get a little feedback from people who have done it before and want to hear first hand pros/cons etc.

Cheers,

Antny

[jonny lovegrove]

Re: To short stroke, or not to short stroke?

Just buy a weaker spring mate.

[HuntR]

Re: To short stroke, or not to short stroke?

Short stroking will also affect your accuracy. As it will alter the volume of air inside the cylinder. It could make it far less accurate. So it's all trial and error

[Antny]

Re: To short stroke, or not to short stroke?

I've got a madbull 6.03 tbb installed and flat hop it with madbull blue bucking, and given I only play cqb at a very close quarters site, if it does effect accuracy it should be minimal. Thanks for the feedback tho.

[Figjam]

Re: To short stroke, or not to short stroke?

If your objective is just the FPS, spring is the right answer. For trigger response you may very well do better with a pre-cocking mosfet as a relatively easy if not so cheap way to go.
I have short stroked my CQB M4 by 3 teeth off the sector gear, and am happy with the result but it was definitely not the easy route. I now have an m120 spring in it to get it to shoot 320fps, and the cycle rate is pretty good off a 7.4v mosfet. But I've achieved better results running 13:1 gears and a torque motor.

[sj_asc]

Re: To short stroke, or not to short stroke?

A slightly weaker spring would be the easiest option. The difficulty of short stroking would depend on wether or not your existing piston has more than one metal tooth. It's not likely that you would see any changes to accuracy as a result of slightly less volume. After all, those that choose to do the AoE corrections with sorbo pads loose about as much volume as the equivalent of nocking a tooth off.
What you don't want to happen is for the ROF to climb significantly as a result of the reduced load as in addition to the subsequent slower piston return times, you may face premature engagement issues (sector gear attempting to engage the piston before it has returned to battery)

[Vex]

Re: To short stroke, or not to short stroke?

New spring. If your buying a mosfet with active breaking, then get a BTC Chimera / Spectre which can also do pre-cocking for best trigger response.

[dexadrine]

Re: To short stroke, or not to short stroke?

Another way to get better trigger response is to install a hi speed gearset such as 13:1 and a "slow" high torque motor such as a jg blue. Combined with 11.1 lipo things get very snappy.

[dave38x]

Re: To short stroke, or not to short stroke?

Another way to get better trigger response is to install a hi speed gearset such as 13:1 and a "slow" high torque motor such as a jg blue. Combined with 11.1 lipo things get very snappy.

That's a waste of battery space though, a lonex A2/shs high torque and a 13:1 gearset will give you 25rps+ easily on a 7.4 lipo which is all you need for fast trigger response.

To get a gun using that combination under 350 you'll almost always have to short stroke too (having built five guns to that exact setup).

OP: I'd short stroke the piston by two teeth and see where that leaves you (you will need a chrono obviously) - you can always just take a little off the spring after that. If you want to increase RoF then you can either stick a high torque motor in, or run 11.1 or both And don't worry about loss of accuracy from "over voluming", my M4 gearbox is optimised for a 330mm barrel but my short upper running a 229mm barrel still hucks the bbs out in a beautifully straight line. Accuracy loss from "over voluming" is a myth.

[Antny]

Re: To short stroke, or not to short stroke?

I should mention i have a G&P M120 motor installed. I think i may give it a go and hey, even if it doesn't work out great, i can always just buy a new sector gear. Thanks for the replies tho guys. Will probably update my findings once done if i remember.