Hey /k/ I'm making my own suppressor and was interested in checking the effect of the suppressor on the gassing of my AR15 but I'm getting results that are completely the opposite of the expectations.I captured ten shots with a flash hider and my suppressor on smartphone high speed video (480 fps), counted how many frames it takes for the bolt to complete one cycle and averaged out the results, here's what I got:Unsuppressed avg: 39 frames per shot (around 745 RPM if it were full auto)Suppressed avg: 41 frames per shot (around 698 RPM if it were full auto)This goes completely against my expectations. Isn't a suppressor supposed to increase the gassing of the rifle and therefore increase bolt velocity, cycle time, and finally RPM?This result was repeatable at another range trip, the suppressor was again ~40 RPM slower.
I want to add that the suppressor is a pretty large volume design with some flow through aspects so I wasn't expecting it to increase operating pressures too much.But I cannot fathom how it could reduce them either.All shots were taken with magazine removed so the varying follower pressure wouldn't affect bolt movement.
>>64508449Your measurement method sucks and cannot be trusted to draw any kind of meaningful conclusion from.
>>64508438>>645084490a. something is up with your measurement system0b. you aren't doing enough samples to actually get out of random error1. your measures are correct and its down to the specifics of your gun and gas system. over pressure slamming the springs and such is creating choke points in components not intended to run at higher pressure so the whole system is not running as smooth and fluid as it should be. adding more gas to a complex machine does not necessarily have a trivial linear relationship. if you got a decent agb (and you should) then you can play with tuning and see what the relationship looks like across a range of settings. normal advice is gas should be the lowest possible that still cycles reliably
>>64508570also good luck whether it comes out as good as you hoped or not making your own fun stuff and learning and experimenting is always based
>>64508478What's wrong with it? On the video I start counting from the first frame the bolt is still and finish at the last frame the bolt is still again.Could you recommend me a better testing methodology for the affect of the suppressor on the rifle gassing? I'm running an non-adjustable 20'' AR15>>64508570I'm also guessing it's just some random error in my testing but I'm irked that I got the same difference in RPM two times with different ammo on a different day.1st day (number of frames per bolt cycle):Unsuppressed Suppressed37 4137 4741 4446 4545 4440 39N/A 42N/A 47Averages41.0 frames 43.6 frames702 RPM 661 RPM1st day (number of frames per bolt cycle):Unsuppressed Suppressed37 4039 4237 4536 3939 4138 4438 4142 3838 N/A40 N/A41 N/AAverages38.6 frames 41.3 frames745 RPM 698 RPM
>>64508438Are you sure your camera is filming at steady rate?
>>64508612I do not know. It's a smartphone camera.
>>64508626It's not good enough for what you are trying to do
>>64508631I see.Do know of any other method I could use to compare the gassing of suppressed vs unsuppressed?
>>64508611Do you have a chronograph? It would be interesting to see if your ammo is just inconsistent, and that would help either confirm that or rule it out. Or just increase your sample size.
>>64508750Can you put a microphone probe against the barrel and see when does all the ruckus start and stop? Mostly likely you can find peaks when metal bang on metal.Most audio device easy collect tens of thousands of sample a second.
>>64508750Unfortunately not.The ammo is also handloaded and not the greatest batch, at least accuracy vise. I was hoping for a clear difference between unsuppressed and suppressed.>>64508934That sounds like a good idea actually. I was planning to try and take some sound measurements of the suppressor anyhow. I'll buy an instrument mic and place it far away, 10-20m from the gun to cut the decibels and flatten the sound curve and try to capture the gunshot sound.
