Of course, the gas block can be adjusted without one....by taking apart the front of the rifle, removing the gas rod and cup, and then a standard wrench to loosen the threaded part under the cup, and the gas adjustment then spins easily by hand.
I had to set mine to 1.5. At 1.3 I was getting stovepipes, and the even more dreaded 'rechambered empty casing', which would then jam, including the bolt.