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Posted: 1/20/2011 3:54:54 PM EDT
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Here is some cool high speed video of the STG.
Ejection Please dont mind the lack of recoil control as I shot it one handed and unsupported so that I could keep my ugly mug out of the video. You can see the impulses from the actual firing and the bolt carrier reaching the end of its travel. There is even slight carrier bounce occurring. Take a look at the take down latch too for some crazy flex in that area of the stock Firing Some highlights from the video of it firing: 
You can see a lot of the recoil being dispursed from the barrel, to the receiver and then to the stock....and then again as the carrier finishes its rearward travel. If you look real closely you can see the barrel flexing during and after the round leaves the barrel. 
And be careful where you put your hands 
Pretty cool stuff I thought I would share and the more I look at it, I wish I would have got much, much higher FPS...I can go up to 250k (file size would be insane though). I can put the original files up for sharing on my FTP. PM me for details if you want them. They are big though (350 and 600 mb) and are .avi |
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Pretty. Damn. Cool.
Looks to be a lot of movement throughout the whole rifle after the shot is fired. Are most rifles like that, or is that because of the less than perfect fitment on the MSAR between the stock and receiver? I genuinely don't know. *NOTE* I love my MSAR and I don't want some asshole replying to this thread with MSAR hate. *NOTE NOTE* - I think it's ridiculous I had to put up that first note.....damn haters. |
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Quoted:
Pretty. Damn. Cool. Looks to be a lot of movement throughout the whole rifle after the shot is fired. Are most rifles like that, or is that because of the less than perfect fitment on the MSAR between the stock and receiver? I genuinely don't know. *NOTE* I love my MSAR and I don't want some asshole replying to this thread with MSAR hate. *NOTE NOTE* - I think it's ridiculous I had to put up that first note.....damn haters. I think it's pretty common for production rifles. In a high end match grade rifles, stock bedding is designed to prevent just that. |
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Actually Keith, my take down latch is very snug to the receiver. the problem is there is too much tolerance between the latch and the stock. it gets ampified during the recoil because the stock is actually flexing. All together in rearwards slop I am estimating the rifle has about .030" (barrel -> receiver, receiver -> stock)
Now, the impulse felt when all that mass moves .030" is quite significant, the video proves it. I will look into what camera we have, I didn't take note of it, but I will. I will say that all the movement is pretty common, I have watched videos of LMC (least material condition parts used to assemble the rifle) AR-15s and the amount of movement is similar to my STG. That said, at max material...they are much tighter and the only things moving are really the mag release button and bolt release. AK's exhibit the same thing. The round popping into the chamber was also an eye catcher, maybe next week if I have some free time Ill get a shot of the feed ramps in action. The rail, being attached to the receiver is affected by the impulse of the barrel slamming backward into it. The bouncing is that energy being shown in a what is essentially a cantilevered beam. Any other video requests? 
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Quoted:
Any other video requests? Yeah, but that will have to be in BOTD.
But really, I think you now have a new position here working with high speed video. Great work and I will stay tuned. Maybe if you can get some more interesting video up we can get it tacked. |
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Quoted:
Actually Keith, my take down latch is very snug to the receiver. the problem is there is too much tolerance between the latch and the stock. it gets ampified during the recoil because the stock is actually flexing. All together in rearwards slop I am estimating the rifle has about .030" (barrel -> receiver, receiver -> stock) Now, the impulse felt when all that mass moves .030" is quite significant, the video proves it. I will look into what camera we have, I didn't take note of it, but I will. I will say that all the movement is pretty common, I have watched videos of LMC (least material condition parts used to assemble the rifle) AR-15s and the amount of movement is similar to my STG. That said, at max material...they are much tighter and the only things moving are really the mag release button and bolt release. AK's exhibit the same thing. The round popping into the chamber was also an eye catcher, maybe next week if I have some free time Ill get a shot of the feed ramps in action. The rail, being attached to the receiver is affected by the impulse of the barrel slamming backward into it. The bouncing is that energy being shown in a what is essentially a cantilevered beam. Any other video requests? My STG556 fails to feed occasionally out of the right side of the magazine, giving me a "bolt over base" failure. I've tried different mags and different ammo but it still happens every now and again. This has kept me from selling the gun since I wouldn't feel right about pawning off my problems on someone else. Anyway, I note that this peculiar problem only seemed to start after about 1,000 rounds had been through the gun. I also note that the stock doesn't fit the receiver as snugly as it used to and have wondered if the loosening stock is part of the problem. It would be great to get some video like this of my gun when it does malfunction... |
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Rizzo is using some top-dollar gear if he can get 250k FPS, but you can get high-speed video of your own with a cheap Casio.
I have a $300 EX-FH25 that goes up to 1000FPS, which is plenty for diagnosing mag feed issues. It's best to have two people, one shooting and one filming. The focus is very important with the small resolution you get at 1000FPS and it's best to set it manually. Use a tripod.... not for the steadiness, high-speed video doesn't require it. So you don't change the distance between yourself and the subject, messing up your focus. That video says it's 7000FPS but it's been sped up...otherwise the gun would have a cyclic rate of 20,000RPM.  I think it's been sped up to around 250-500FPS, not sure.
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Quoted:
Rizzo is using some top-dollar gear if he can get 250k FPS, but you can get high-speed video of your own with a cheap Casio. I have an EX-F1 which has roughly-similar capabilities to your camera. I'm still interested in knowing details about what type of camera the OP is using to capture these videos, even though it's likely well out of my price range... |
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I am 90% sure that this is the camera. I know its a Photron but Im not completely sure as to the model.
eta: it was shot at 7000fps but is being played back at 30fps. So the 20 or so seconds of video equals roughly 600 frames in real time. The event therefore lasted about .085 seconds. Its rearward bolt velocity is within 1% of an M4 clocked at 850ish rounds per minute. The forward velocity for whatever reason is twice as long as that specific M4. |
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