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Just wanted to get some opinions on this idea.
-Yes it should work
-maybe
-definitely not don't even try it



Basically when the piston opens(brown cylinder), air enters the port and forces the bolt(red part) forward thus allowing the air to pass down and into the barrel propelling the projectile forward. In the mean time, as the bolt moves forward, it blocks air from going up while grabbing another marble. A spring(not shown) will be used to return the bolt to its original position thus dropping the marble into the barrel for the next shot.. And REPEAT.
I know things always look good on paper, but does this design have any chance of working? Besides the decrease in efficiency by having to redirect the air, what are some of the weak points of this idea (if any)?

one concern I have is the with the bolt. When the air hits it, would it
1. slam it forward so hard that it would damage it
or
2. once the bolt moved forward enough to create and opening, would the air just squeeze by without pushing the bolt far enough forward to pick up another marble

I'll probably start building it tomorrow night, but if someone says 'no, it will definitely not work' then I won't bother wasting my time.

What are your opinions?

Plus, if this is an old idea and has already been done(successfully or unsuccessfully) please let me know.

Your picture's down, upload it on spudfiles

pic doesn't work. i checked to see if my pc was acting up but it's not. ur pic just isn't showing. try uploading it again. i really wanna see what ur trying to do. thanks.

also, what r u designing it for? if it's for airsoft then it doesn't need to be super efficient. it just has to do the job it's intended. u don't wanna kill any one.

I think that its a GREAt idea...... In fact im pissed I didnt think of it.

Just be sure to give both the blow-foward piston and the actual air piston O-rings, air loss out the pilot and the blow-foward will be substantial without them, resulting in poor velocities.

It does look like it should work. Maybe a little complicated to build, but definitely doable. Nice work tvouthilak. Now, let's see the real thing.

I believe it should work, although it's going to have a huge amount of dead space.
This might be preferable to the flow restrictions of a blow-forward breech, although it is a lot of extra design effort.

I'm not exactly sure, but it may not work too well because the the magazine looks a little far away from the bolt and all the air may rush out the barrel before it pushes bolt far enough. You could probably shorten the tube holding the bolt, the bolt itself, and make the magazine closer. Overall this an awesome idea!

I still can see the diagram please upload it to spudfiles or photobucket or if any of you can see it could you do it, from the description it sounds like a classic blow forward bolt

edit: okay now I see it but why use this instead of a classic blow forward bolt, there is a lot dead space, do you have problems with multiple marbles loading at the same time?

I like it it should work, now try it!

It should work, but in terms of performance I doubt it would be any better than the blow-forward breech, and construction would be much more involved.

Also, your concerns about the bolt slamming forward are more than justified, a buffer of some sort is definitely in order.

Hey, thanks for all the feedback. Seems I got enough positive opinions to go ahead and give it a try.

also, what r u designing it for? if it's for airsoft then it doesn't need to be super efficient. it just has to do the job it's intended. u don't wanna kill any one.

I'll be shooting 1/2" marbles with it.

Just be sure to give both the blow-foward piston and the actual air piston O-rings, air loss out the pilot and the blow-foward will be substantial without them, resulting in poor velocities.

Thanks for the suggestion. I'll make sure to do so.

I'm not exactly sure, but it may not work too well because the the magazine looks a little far away from the bolt and all the air may rush out the barrel before it pushes bolt far enough. You could probably shorten the tube holding the bolt, the bolt itself, and make the magazine closer.

My thoughts as well. I'll see what I can do about shortening the whole mechanism.

okay now I see it but why use this instead of a classic blow forward bolt, there is a lot dead space, do you have problems with multiple marbles loading at the same time?

I've not built the classic blow forward bolt, but yes, my design was an effort to avoid multiple loading at one time.

Alright, nothing to do now but give it a go.. thanks again for your opinions. Keep them coming..

This is one of the first actually innovative ideas (no offense, guys) I've seen since I've joined. Of course, I'm being humble, so if anyone thinks any of my ideas count as innovative, I'm always open to congratulations. Anyway, this looks just plain dandy. If you can build a working prototype, you will instantly become one of the most respected members here on spudfiles.


And as a response to a post made a few months ago, yes, it does seem like making a full-auto design is a rite of passage here.

the dead space concerns me a bit. i think u should use a low volume cylinder. u also will have to seal the hopper so it won't leak the pressure. that's just my opinion, though.

i like that u plan on using a coax. i'm working on a similar project. http://www.spudfiles.com/forums/auto-qe ... 16399.html

how do u plan on making the coax automatic (filling and piloting fast)? i'm trying to find a very quick way to do this. so far i think i can get 2 pilots a second. another idea involves a high resistance mini pneumatic piston used to achieve full-auto. u got any ideas? or have u not come to step yet?

i-will wrote:the dead space concerns me a bit. i think u should use a low volume cylinder.

Not exactly sure what you mean by this.

how do u plan on making the coax automatic (filling and piloting fast)? i'm trying to find a very quick way to do this. so far i think i can get 2 pilots a second. another idea involves a high resistance mini pneumatic piston used to achieve full-auto. u got any ideas? or have u not come to step yet?

Right now I'm just concentrating on the auto reload portion. I'm not really interested in making this a full auto firing gun (yet), but more of a rapid repeater. With the way I've designed my firing mechanism, I can usually get three shots out of my air chamber before having to refill.. But more on that later.....

......Construction has begun on the prototype and things are looking promising.

The mechanism seems to work pretty flawlessly when operated by hand. Feeds marbles just as designed. However, I attached it to the gun for a couple test firings and I may have underestimated the force of the air pushing the bolt forward(I think I'm going to need some stronger springs) I was only testing it at around 20-30 psi and the whole thing feels like it is getting slammed forward so hard that I would be afraid to go any higher. That would make for a pretty lousy gun if you were only shooting it at 30 psi:(

Any suggestions on how to dampen the bolt more effectively? Plus, the bolt only has a travel of about 1 1/2" max. Does that sound like enough or should I give it more travel, because my fear of the bolt not moving far enough forward to pick up another marble is obviously not the issue...

I'll try to get a video up this weekend so everyone can see that it does work(just needs some tweaking)