Monday, September 9, 2013

[Mod] Swarmfire Reliability

Up now: how to set up a Swarmfire rotation system to handle high-rate full auto, worn parts and adverse conditions without skipping a beat.

Tear it down and pull out the operating rod.

Now fully strip that. There are 2 washer head screws on either side of the safety spring in the middle. The tip pawl is held in by a pin. Drive the pin out with a punch or thin object from the bottom side; be careful as this will release a small spring.

Note the knurling on one end of the pin - that end faces up, and the pin needs to go in from the top, non-knurled end first, when you reassemble later. Don't lose the pin or the pawl.

The first order of business is to replace the stock pawl spring. This is what causes random dryfires in the middle of a cylinder especially in full auto; the weak spring does not return the pawl into position fast enough to engage the next cam tooth and rotate the cylinder. This is why Swarmfires running high ROF can get all skippy on you. Same with older units in which the pawl is worn, and with dirty environment problems with these.

 Find something with more load than stock which fits the hole in the op-rod body without binding and test-fit with the pawl. It's not rocket science, just throw random springs at it until you find one that works. You can bump the force quite a bit without any problem.

Reinstall the pawl, drive the pin back in flush with the surface of the rod. I like to put a drop of CA on top of the pin for insurance.

Mod two involves the safety spring.

This spring allows the op-rod to telescopically collapse harmlessly, thereby saving your parts from getting fragged, if the cylinder or front op-rod assembly gets jammed hard. We are not going to delete or defeat this feature nor replace the spring; but rather add a slight, and optional, boost to the breakaway tension of that spring by preloading it a little.

Cut a random bit of durable hard material <1/4" thick to fit under the end of the spring and fit inside the channel without friction. This will still allow proper operation of the safety device. Here I chopped up a bit of PVC sheet with dikes until it fit - not a precise mod here. Install as shown toward the rear end of the op-rod assembly. Reinstall the 2 screws.

Now lube everything up lightly with white lithium grease (cam follower pin and shaft slot on the rear rod, pawl and top/side surface on front), drop that back in your Swarmfire and proceed with reassembly.

1 comment:

  1. Rawr, gonna have to do this to my Swarmy. Thanks for the tip!