Blowback problem

[athomas]

One of the main concerns of the automag guns is the amount of blowback causing feed problems. Airgun Designs has addressed this problem quite successfully using longnose bolts and powerfeed bodies. I was wondering what the effect of reducing the bolt spring tension would be.

The automag bolt spring tension is a value that causes the bolt to return to its open position (valve closed) with approximately 50-60 psi of residual air still in the chamber. This also means that there is a fair amount of air pressure still in the barrel as well. It is this air that expands in both direction to follow the ball out the barrel plus blow back up the feed tube. By reducing the spring tension, maybe the chamber pressure would cause the bolt to stay forward longer lowering the residual pressure available to cause blowback problems.

A shorter spring due to wear causes bolt stick problems. Would a proper length spring at a lower tension work? In theory it would, but in reality I not entirely sure.

Is it the pressure in the chamber that keeps the bolt forward after the initial push, or is it the time it takes the spring to rebound and push the bolt back to its open position that ultimately determines the bolt cycle time?

Lets get some discussion on this topic.

[ezrunner]

redesign spring setup

It would be possible to put two springs and

guides of a small diameter into the rail of the

automag. Protruding from the rail would be two

"hands" or "nubs" that would push the bolt back

to it's rear position.



This would accomplish a few things.

A: The front of the bolt could then incorporate

an o-ring to reduce blowback

B: There could be screw based adjustment from the

front of the rail for the tension on the springs

C: The Delrin bolt would be a reality since

the primary cause of wear now seems to be the

spring.



Tom, this is Rob from Clemson. I play w/

phil & walt. We talked about your bolt, and

I would love some feedback on this idea.



-rob

[AGD]

All of these issues have been resolved in the latest round of research. Please stanby while we do the final testing, then we will fill you all in.

AGD

[Bob Mundon]

im new here but id figure id just post this in here and not make a new thread, they are somewhat related (both chop balls)

i just ordered my minimag, and ive heard without the foamie balls chop easily, is this true? and ive also heard it falls off rather easily and extremely hard to reattach

[BlackVCG]

No. The foamie bolts are designed to reduce ball breaks. They have nothing to do with chops. The foamies will stay on as long as you use a good epoxy.

[Bob Mundon]

ah, epoxy, thats one suggestion i never heard, why the hell didnt i think of that myself