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Posted: 8/22/2007 12:36:32 PM EDT
| How fast is the buffer traveling when it comes to the end of its travel? |
That's a Microsoft tech support answer. Technically correct, but absolutely no help. Bravo. I salute you. Perhaps the OP should have asked how fast the carrier/buffer are traveling before they hit the end of the buffer tube. I would not have an answer to that question, but at least it would be the correct question. 
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Randall, you kill me sometimes.  That answer was "almost" as useful as the "Microsoft Tech" version... (I like reading your posts. They are almost always spot on and very informative. You have good pictures too. The buffer weight one you just posted is an excellent example.)Of course in this case, you must be up passed your bed time, you forgot to mention that to properly answer this question we need more information. The OP needs to specify all of the following: Is this a rifle or carbine? What buffer is being used? What spring is being used? What gas tube length is being used? What ammo is being used? How clean or dirty is the gun at the time in question? What kind of lubricant are you using and where/how much is applied? Even the condition of the gas rings will affect the overall speed of the buffer/carrier/bolt movement although to a very minor extent. I'm kind of curious as to why the OP asked the question. I don't believe I have had that particular question asked before. And Just like Randall, I have no idea at what speed the buffer is moving immediately before it hits the end of the receiver extension (AKA, "buffer tube") and stops either.  (I am also up way passed my bed time and I have to get up in 3 hours!)OK, who wants to go next 
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Note the username "Subnet" which is a computer term, hence my analogy to Microsoft tech support.  We have a high speed camera at my regular "day" job that I have been REALLY wanting to take to the range to photograph the AR in-action. If I had this done already, I could have said what the carrier speed is by measuring the stroke of the carrier and counting the frames that it took to make that stroke or by simply measuring how much stroke occured in the last two frames before the carrier stopped. I already have a cut-away receiver that I intend to use for this testing. Carbine and rifle barrels will be tested as well. |
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According to some rough "seat of the pants" figuring for a carbine, at around 720rpm cyclic rate, I'd say it is moving approximately around 8.3 -8.5 fps. Give or take a little. Not exact, but approximating an average speed. But yes, technically AT THE END of its travel, it would be zero, momentarily. |
I yam what I yam.  Seriously, in addition to the clarifications requested already, I'd think it's still more complicated than that. It's pushing up against a spring that increases it's force against the buffer the more the spring is compressed. The speed would vary, in other words. The most useful answer would be similar to the informative (and way cool) post on gas pressure you did. You'd have to measure the speed at different points in the cycle and graph it. |
Using the cyclic rate would provide a great seat of the pants guesstimate for the average velocity of the carrier group during a full cycle, however: This of course would raise the additional question as to whether or not the carrier assembly was moving at the same speed in both directions. The first part is gas driven, the second spring. I feel that logically that two different velocities are going to be found here. |
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