Random thoughts:
1) crack - bang - breaking the sound barrier precedes sound of the shot which is confusing as heck - crack bang. I remember back when targets on an Army rifle range were raised and lowered by people in deep trenches (as recent as the early '90's at some ranges) where you can safely hear what it was like to be down range
2) your brain - the mind cannot place a location of the 1st shot. that's why soldiers will duck and cover but then put their head on a swivel to try and place the 2nd shot they expect to hear. the 2nd shot give you direction and then your eyes can pinpoint location from the 3rd shot on with the flash. modern practice is to lay down suppressive fire in the direction of the sniper asap before getting digital on their location
3) flash vs sound - suppressors are just as much a flash suppressor as they are a sounds suppressor
4) load out - the situation dictates the load out. think forest vs field vs urban. being super stealthy is not always the goal as much as it is reaching out and touching someone. also, a suppressor adds a lot of barrel length which sucks in an urban environment. M24 vs M110 (AR10) - different length, 5 rounds vs 20 rounds - a lot to consider. also, snipers have always been part of a team and they have people protecting them from being either bum rushed or snuck up upon
5) Barrel length and accuracy - barrel length does not equate to accuracy. it IS proportional to velocity which is why the AR15 rifle is making a comeback due to its projectile velocity. Now one can argue that the farther iron sights are from each other helps accuracy but we are assuming that all systems discussed here have optics so the iron sight argument is out. there are a lot of precision shooters that choose an AR10 platform vs a bolt action for this reason along with more bullets. Sidebar - practice is so important as it relates to ultra fine motor skills. with my used / very old 30-30 lever action (top ejecting so scope is no bueno) with a Lyman peep sight, I can shoot circles around once-a-year hunters at 100 yards with their Leupold scopes and match ammo because I try to get to the range frequently and practice. on top of fine motor skills is breathing and repeatability. look at professional basketball players when they "shoot" from the free-throw line - fine motor skills, breathing and repeatability. Same stuff
6) Point of impact - suppressors change POI. not because of what it does to the gasses but more that you've added a mass at the end of the barrel so the barrel's harmonics have changed. I've added a PRS EC Tuner Brake (Eric Cortina is on YouTube - check him out) to my precision rifle and cannot wait to see the changes to my groupings but look at what other people have experience by changing a mass at the end of the barrel a 1/10th of a turn in the image attached below
7) A change to your system - mechanical resonant frequency is f=1/2π √(k/m) where "m" is mass and "k" is the spring constant of the system. change either or both and "f" changes which is the "harmonic" mentioned above. and lastly
8) Recoil - muzzle brakes vector gasses backwards to offset recoil as to keep "eyes on target" while a suppressor vectors gasses forward. each has a different impact to recoil so the user must balance the benefit / impact to their load out
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