Both "used method" and "method used" can be correct, but they serve different purposes. "Used method" often acts as an adjective phrase to describe a method that has been utilized, while "method used" emphasizes the method itself, highlighting its application. Depending on the context of your sentence, you can choose either. Generally, "method used" is more common in formal writing.
method used to demonstrate an experiment or to imitate a phenomenon
hands
Lots of inventions use the scientific method.
The Scientific Method is a method made by science
The most common way to commit suicide is by using firearms (guns) or drug overdose.
I cannot find the phrase "roman method" used anywhere in Shakespeare. In Antony and Cleopatra, Cleopatra speaks to her servants on the death of Mark Antony saying "Let's do it after the high Roman fashion," where she intends that they all commit suicide. I take it to mean that their attitude was that of the high Romans, who would commit suicide rather than be dishonoured - not a reference to a method of suicide. If it is a reference to a method, then it might be a reference to how Mark Antony died, which used to be depicted by the actor falling on his sword, having stuck it, blade upwards, in the ground.
suicide
It isn't new, people have used it probably since the train was invented. It is kind of hard to miss with a train or wound yourself with one.
Both "used method" and "method used" can be correct, but they serve different purposes. "Used method" often acts as an adjective phrase to describe a method that has been utilized, while "method used" emphasizes the method itself, highlighting its application. Depending on the context of your sentence, you can choose either. Generally, "method used" is more common in formal writing.
Irrigation is the prime method used.
English
Immolation is a form of suicide because you are killing yourself using fire.
Romans had several methods of committing suicide, depending on their status and circumstances. These could include using a sword to stab themselves in the heart (known as "falling on their swords"), consuming poison, or opening their veins to bleed out. Self-immolation was also a method used in extreme cases.
Method used to conduct scientific experiments.
a method anders used
Evils didn't commit suicide. His death was accidental caused by a cocktail of prescription drugs he used to take.