pneumag design questions

[Joe McGuire]

What is the maximum bps for a pneumag?

I'm looking to build a pneumag that can cycle as fast as I can shoot it. I want to be the limiting factor, not the gun.

Whats the best valve to use? Im looking at the msv-2.

Im looking at an mpa-3 actuator. With a lukes stainless steel piston. I think these parts are pretty standard. Are there any other/better choices?

Is a qev necessary? What is the benefit of having one. Ive seen recently the qev is being installed in line before the actuator, is there any benefit from having it directly mounted to the actuator?

When I install the valve, I think I read that it was ideal to have the rod that the trigger depresses to activate the valve as high on the trigger as possible, to lighten trigger pull. Is this true?

Any help would be appreciated. Thanks.

[longi]

16 bps is the maximum for a pneumatic trigger system. The Msv-2 is a good choice, i've done 2 frames now, and both rip! Luke's steel rams are about the best choice for the actuator. The QEV isn't neccerssary, although it helps to keep the trigger pull slightly lighter, and i belive if your fingers could pull faster than they do, then it gives a higher rate of fire. High is good, but not too high, as you end up hitting the curved part of the trigger at the top, and the rod then aquires a sort of sticky effect and the trigger pull becomes awfull. Acouple of things to watch out for.
1.. Round off the end of the rod that makes contact with trigger as much as you can making as much of a semi circle, otherwise you get the sticky effect and you won't be able to walk the trigger and you'll probably become suicidal with the wondering why you can't get it to walk!!! Half my problems were caused by this one thing. You want the rod to glide across the surface as much as possible when the trigger is pulled. You'll know what i mean when you get to that point.
2..If you go the MSV-2 route set the MSV-2 at different angles until you find the gun walks easily.
Here's my rather bad attempt at walking the trigger after emptying 3 hoppers one after the other as a warm up, then getting to 4th hopper and running out of steam!

http://media.putfile.com/longis-pneumag-working

I was pulling at around 10 bps in places, although the first couple of hoppers i ripped out much more qiuckly. But you'll have to take my word for it!

[Joe McGuire]

Anybody else have any words of wisdom?

[Pneumagger]

A lot of electo pneumatics have a hard time breaking 20 BPS when shooting paint - so I would imagine that is about the limiting factor. Scotts hellrazor EP mag gets about 20 bps without a QEV... so that might even get you another few BPS or so.

The thing with a homemade pneumag is; the faster you pull the trigger, the cleaner and more concise each pull needs to be - or else the short stroke propability raises. Personally, once I hit around 14-15 bps (goldwaved) I begin short stroking.

If your pneumag is well made - you will be:
a) the limiting factor
b) an anomoly

[longi]

heh heh!