The Kretz was submitted as part of the British Self-loading rifle trials. However, the Kretz did not fare well in the tests, as it was extremely complicated, badly balanced, weak, bulky and extremely heavy among a slew of other reasons.
The Kretz used a coil-assisted blow-forward mechanism. The bolt was mounted on a chain on an internal cam, housing a big clock spring, or the coil. On the spring was yet another chain, mounted on a smaller clock spring, used to cycle the bolt. The muzzle blast would force the left chain forward, storing energy in the bigger clock spring. This would force a transfer arm to engage a dog on the smaller clock spring. The chain would then move back, pulling back the bolt. This would un-coil the smaller clock spring. The chain would be released by the dog on the smaller clock spring, forcing the bolt back into its original position. The action did not work well, and caused the weapon to be labelled "uncertain in its action".