To make an informed decision you must know what cryo treatment will and won't due.
If done prior to drilling, reaming, and rifling it will make the metal easer to machine and in most cases will give a better finish.
It will help with pattern spread due to heat from rapid fire shooting.
I have found that the barrel life and throat life are longer as well.
It will not change the harmonics of your barrel or the bore dia.
The process only works if done properly for the type of metal being used.
I can only go into generalities here but for 416R steel the barrel is frozen to -100 in a freezer over 3 hours then liquid nitrogen is added to the freezer (it is not allowed to touch the metal at any time) to bring the temp. down 10 deg. at a time, and held for a certain period of time, this is done until it reaches -300 deg. it is held at that temp. for approximately 7 hours then brought back up at the same rate as it went down until it reaches room temp. then it is tested for hardness ( it can be very brittle after the cryo treatment ) and then heated in an oven for tempering at 300 deg. for three hours, allowed to cool to room temp. and then re-tempered two more times to reach the desired hardness.
This is a long process but very well worth the effort and expense for what it will do.
This process works wonders for prolonging the life of end mills, saw blades, and barrel and chamber reamers.