View Full Version : AR-15 Buffer Test - High Speed Video
Blog Link (http://vuurwapenblog.com/2010/07/28/ar15function/)
420fps video of 5.45x39 carbine with 3 different buffers (http://www.youtube.com/watch?v=pRn68HwZf34)
1000fps video of 5.56 weapons, 7/29/10 (http://www.youtube.com/watch?v=575Q0O41u5s)
Have you ever heard a rifle manufacturer say that their weapon has been “tuned” to run a certain ammunition while maintaining excellent recoil characteristics?
Do you believe that this is achieved by some sort of magic spell?
Well, if you do, I’m sorry to tell you that you’re wrong.
These manufacturers are simply paying close attention to important factors such as gas port diameter and location, action spring rate, buffer weight and construction, chamber dimensions, and so on. They thoroughly test their weapons to ensure function and allow the end user to put rounds on target in the most efficient manner possible.
Other manufacturers simply assemble an AR-15 out of parts, using components and methods selected to minimize production costs. Testing does not progress beyond exceptionally basic function and accuracy testing (if at all). If you asked such a manufacturer what the gas port diameter of a specific model was, and what testing led them to use that diameter, their answer would probably not be very impressive.
It’s difficult to describe why function isn’t enough. In my opinion, the AR-15 is at its best when it is a system that works in harmony with itself, not simply an amalgamation of parts constantly fighting one another.
To illustrate this point, I have high speed video (well, kinda high speed) of a 5.45x39mm AR-15 using three different buffers. Function with each was what some would call “perfect”. The weapon did not malfunction due to any of the buffer changes, and most folks would be content to use a carbine buffer, because it’s cheap, and “it works.”
What they don’t realize, though, is that the weight of the buffer is not as important when the action spring, extractor spring, magazine spring, etc are all in perfectly functional condition. The weight of the buffer becomes critical when said items begin to reach the end of their lifespan (or were never satisfactory to begin with), or when the weapon has been fired for thousands of rounds without any lubrication, or when various types of ammunition are used.
As you can see, the carbine buffer allowed the bolt carrier to bounce back after making contact with the receiver extension. Many people say that this isn’t a problem unless the weapon is firing full auto. While malfunctions are not as common on semi auto, is this really something you want your weapon doing? Even the heavier 9mm buffer allowed a similar amount of “bounce” – it doesn’t have the heavy internal weights of the carbine or H buffers. The BCM H buffer, though, with its heavier (and separate) internal weights, practically eliminated the issue.
The AR-15 platform is great due, in part, to its modularity. However, this modularity also allows inefficient combinations of parts to function with one another. By understanding how each component affects overall function, the last .01% of reliability can be achieved, and recoil characteristics can be improved.
I'd like to thank Mike Pannone for making me think hard about buffer weight and spring rate again, and especially the importance of the action spring.
Cool! I saw this on Barf and was hoping to find it here.
Interesting how piss poor the 9mm buffer is at bouncing. The Spiked T2 seem pretty good, but not thrilling. And the rifle buffer rules.
Here's another cool bolt bounce video I found a while back... it's a little ways into the video, but it's 3 round burst action with weird music.
http://www.youtube.com/watch?v=vozrLZclXfg
AnimalMother556
07-29-10, 20:42
Interesting stuff. Keep it up.
DaBears_85
07-29-10, 21:05
Wow, excellent post and very well worded.
Heavy Metal
07-29-10, 21:18
Very nice.
Why the bounce with the 5.4oz 9mm buffer but no bounce with the 5.2 oz rifle buffer? Isn't the rifle sprung softer and consequently, wouldn't the spring have a greater tendency to compress some (i.e., allow bounce)?
motorwerks
07-29-10, 23:01
I wish I could get someone that could do 1000fps to record my Tubb flatwire sprung, BCG that's running the Spikes buffer. :D
motorwerks
07-29-10, 23:03
Why the bounce with the 5.4oz 9mm buffer but no bounce with the 5.2 oz rifle buffer? Isn't the rifle sprung softer and consequently, wouldn't the spring have a greater tendency to compress some (i.e., allow bounce)?
Just a guess, but maybe the riffle has had longer to get moving? I assume the Riffle buffer was in a riffle tube?
87 great post man! Very well said. I was actually out at the range playing with different buffers today.
This post reminded me of a small experiment I'm in the process of performing with my SR15 E3. Would it be correct to assume that it would be a good practice to use the heaviest buffer possible, while still maintaining reliability with lower powered ammunition?
Hmmmm. Great timing. I sent Grant a list of upgrades I'd done on my rifle. He said everything looked good but had I considered changing the buffer. I didn't understand why. I do now. The lightbulb just went on. Thanks for the "visual proof"
Nice...
To contrast the weighted buffers, can you shoot a clip of a carbine buffer body only (no weights).
As I understand it, the 9mm buffer you used was solid. Would an X buffer yield different results as it has a steel body with 3 tungsten weights and its mass can reciprocate?
Nice...
To contrast the weighted buffers, can you shoot a clip of a carbine buffer body only (no weights).
As I understand it, the 9mm buffer you used was solid. Would an X buffer yield different results as it has a steel body with 3 tungsten weights and its mass can reciprocate?
Actually, I had forgotten that my 9mm buffer allows slight movement of whatever weights it has inside. There's no obvious way to disassemble it (no roll pins whatsoever), so I'll have to figure out a way to get it open today.
I will be testing as many buffers as I possibly can in the future.
Heavy Metal
07-30-10, 08:54
Nice...
To contrast the weighted buffers, can you shoot a clip of a carbine buffer body only (no weights).
As I understand it, the 9mm buffer you used was solid. Would an X buffer yield different results as it has a steel body with 3 tungsten weights and its mass can reciprocate?
Even better would be an MGI buffer as it has a steel body, three tungsten weights and plunger at the bottom that knocks the weights forward as the buffer is bottoming out in the tube to spread out the energy of impact at the base of the buffer tube over a longer period of time.
It is as heavy as a 9mm X-Buffer.
AnimalMother556
07-30-10, 12:37
Is the rifle buffer in these videos in an A2 stock or is it in the Vltor A5 stock? Do you believe the results would be the same between the two?
Is the rifle buffer in these videos in an A2 stock or is it in the Vltor A5 stock? Do you believe the results would be the same between the two?
It's an A2 stock. I believe that the A5 would be as good or better than the A2, based on the 60,000 round testing that was done by the USMC last year - the PDF was online for about 6 hours before it was pulled, and unfortunately I did not download it in time. The A5 outperformed the A2 and H6 (H3 with each weight cut in half).
However, the only way to know for sure is to test one. I don't have access to one.
AnimalMother556
07-30-10, 12:44
It's an A2 stock. I believe that the A5 would be as good or better than the A2, based on the 60,000 round testing that was done by the USMC last year - the PDF was online for about 6 hours before it was pulled, and unfortunately I did not download it in time. The A5 outperformed the A2 and H6 (H3 with each weight cut in half).
However, the only way to know for sure is to test one. I don't have access to one.
Bummer on the inability to test it. Definitely has me thinking though.
Obviously subjective without a way to clamp the gun down and measure the amount of bounce seen, but it appears to me that in every case the ST-T2 has MORE bounce than the conventional H buffer from BCM.
Very Interesting...
Thanks
Gets me thinking/wondering/curious as to whether it would be possible to construct a clear receiver extension to watch things from the other end. Or cut a slot in the stock part.
Obviously subjective without a way to clamp the gun down and measure the amount of bounce seen, but it appears to me that in every case the ST-T2 has MORE bounce than the conventional H buffer from BCM.
I was a bit surprised by that. It's good to see some good third party testing on this subject. Thanks for doing this 87.
I was surprised at the weight on the T2 as well. I thought they were supposed to be closer in weight to an H2.
motorwerks
07-30-10, 13:00
Gets me thinking/wondering/curious as to whether it would be possible to construct a clear receiver extension to watch things from the other end. Or cut a slot in the stock part.
Absolutely, a rather large section of one side of a standard extension could be removed.
1/2 half inch or more tall, and 4 to 5 inchs long it would have to be thin enough that the spring/buffer wouldn't shoot out the side but it could be done.
Gets me thinking/wondering/curious as to whether it would be possible to construct a clear receiver extension to watch things from the other end. Or cut a slot in the stock part.
I'm already working on something along those lines :p
I had the same thoughts on the ST-T2. The H buffer seemed more effective in every weapon.
motorwerks
07-30-10, 13:06
I would really like to see this same test with wolff, or tubb springs, or one of those fluid dampener buffers.
Would like to see:
-HK416 granular tungsten buffer
-effect of flat spring
Obviously this quickly gets exponential. For every spring you have to try every buffer in every gun. And with more and more combinations of barrel lengths and gas tube lengths....
Imagine just two buffers (ST-T2 and H) and two springs (GI and Wolff) and two barrel lengths (14.5" and 16") and two gas systems (mid-length and carbine-length) and how many individual videos that is.
ST-T2, GI, 14.5", MID
ST-T2, GI, 14.5", CARBINE
ST-T2, GI, 16", MID
ST-T2, GI, 16", CARBINE
Etc. You could be there forever.
Obviously this quickly gets exponential. For every spring you have to try every buffer in every gun. And with more and more combinations of barrel lengths and gas tube lengths....
Imagine just two buffers (ST-T2 and H) and two springs (GI and Wolff) and two barrel lengths (14.5" and 16") and two gas systems (mid-length and carbine-length) and how many individual videos that is.
ST-T2, GI, 14.5", MID
ST-T2, GI, 14.5", CARBINE
ST-T2, GI, 16", MID
ST-T2, GI, 16", CARBINE
Etc. You could be there forever.
Yes. I ran out of ammunition yesterday and still didn't get good video of all the possible combinations (5 buffers, 3 rifles, 2 types of ammunition, and I used the same spring for each). I can't claim that I'll get every combination, but I should be able to get enough video to allow folks to draw their own conclusions.
I have ordered several types of springs (Wolff XP, reduced power, and non-Wolff flat wire) and have some buffers on the way.
I also ordered a BCM 20" upper and will shoot some video with that. The next range trip should have my BCM 14.5" midlength and also a few SBRs.
If I really wanted to get fancy, I could swap ejector springs, I noticed that the BCM seemed to have a little more "oomph" in that regard.
Crow Hunter
07-30-10, 14:12
You could do a DOE study to find out if there is a statistically significant difference between each of the buffers.
I would just set it up in a single rifle and only change the buffers. Keep the rifle and ammo as a constant. The only variable would be the buffer, it would be a pretty small matrix. If you find out there is statistical difference between any of them, you could just do a test between those that are different.
Alternatively you could set up the DOE to show which combination of factors (rifle, buffer, spring, etc) but that would require alot more parts/rifles/ammo to get a 95% confidence interval.
PM me your variables and what you plan on measuring and I can set it up for you in Mini-tab and give you the run order and sample combinations if you are interested.
Won't take me long and besides, it is alot more interesting than what I am working on now.:lazy2:
eternal24k
07-30-10, 14:17
I'm hoping for:
1) 10.5" SBR
2) Vltor A5
Yes. I ran out of ammunition yesterday and still didn't get good video of all the possible combinations (5 buffers, 3 rifles, 2 types of ammunition, and I used the same spring for each). I can't claim that I'll get every combination, but I should be able to get enough video to allow folks to draw their own conclusions.
I have ordered several types of springs (Wolff XP, reduced power, and non-Wolff flat wire) and have some buffers on the way.
I also ordered a BCM 20" upper and will shoot some video with that. The next range trip should have my BCM 14.5" midlength and also a few SBRs.
If I really wanted to get fancy, I could swap ejector springs, I noticed that the BCM seemed to have a little more "oomph" in that regard.
My *guess* is that ammo, barrel length, and gas tube length really don't matter, at least in terms of bounce, and especially provided you use some full-power ammo like XM193 or better. Spring and buffer are probably the only things that really matter.
Why the bounce with the 5.4oz 9mm buffer but no bounce with the 5.2 oz rifle buffer?
The buffer is not a simple weight, in order for it to "buffer" it has the sliding weights. The sliding weights help to keep the buffer from rebounding.
The 9mm buffer has little if any movement of weight and is simply a cheap way to keep the blowback 9mm bolt closed longer.
9mm buffers are not suitable for a gas operated AR.
I disassembled the 9mm buffer I was using. It contained 3 steel weights just like a standard carbine buffer, but the body weighed 3.3oz instead of .9oz. There were more "pads" between the weights than normal. The weights could still move, but not by much. As it was, it was, as many have said, unsuitable for an AR firing rifle cartridges.
I pulled the tungsten granules out of a ST-T2 buffer. There was hardly any room for the granules to move inside the buffer body. I poured most of the granules (2.7oz) into the 9mm buffer body, leaving out roughly .5oz, for a total weight of 6.2oz. I will see how this randomly created buffer does, along with an H2, and an el cheapo action spring I had lying around from the bad old days, while I wait for more components to arrive by Pony Express.
carshooter
07-30-10, 15:41
Very informative videos. Thank you for taking the time to do this.
When ya'll are speaking about the H buffer, BCM has 3 different ones. Which one is being tested?
militarymoron
07-30-10, 15:54
BCM has only one H buffer. the others are H2 and H3.
That was what I was wondering if it was the H, H2 or H3 buffer that was being used.
If you're trying to establish a baseline of comparison, shouldn't you remove some of the variables and shoot each one from the same rifle with the same spring? Then you could perform a similar test by swapping out springs while using the best performing buffer. Hopefully, This would help identify the best combination for that particular rifle, assuming that the combination of the two would not induce malfunctions. A rest like a lead sled with a velcro strap to hold down the rifle might be handy as well.
You could then test the same combinations (buffers, then springs) on different length barrels to see how the changes in barrel length and gas port size affect bolt bounce and what buffer performs best for each barrel type. The real problem is that gas port sizes will vary between manufacturer, so you're almost better off to test certain barrel lengths only from known quality manufacturers like Colt, BCM, Noveske and maybe DD. I'm thinking maybe just one barrel of each length so that you know you are not seeing a difference in gas port sizes affecting the results.
Once you establish a good baseline for say, a 14.5" with carbine length gas, you could later test the "best" combo in different makes to compare an LMT, Colt, DD, BCM and Spikes all in 14.5".
Unless you narrow down the variables, the data will be hard to extrapolate into useful information due to an exponential number of variables. I'm really looking forward to seeing the results.
I used an H2 buffer today. This video contains 8 shots - carbine, H, H2, and rifle from the Spike's carbine and the BCM midlength. All footage other than the H2 is from yesterday's video, I simply left them in for ease of comparison.
http://www.youtube.com/watch?v=q7l6KlNDJg8
If you're trying to establish a baseline of comparison, shouldn't you remove some of the variables and shoot each one from the same rifle with the same spring? Then you could perform a similar test by swapping out springs while using the best performing buffer. Hopefully, This would help identify the best combination for that particular rifle, assuming that the combination of the two would not induce malfunctions. A rest like a lead sled with a velcro strap to hold down the rifle might be handy as well.
You could then test the same combinations (buffers, then springs) on different length barrels to see how the changes in barrel length and gas port size affect bolt bounce and what buffer performs best for each barrel type. The real problem is that gas port sizes will vary between manufacturer, so you're almost better off to test certain barrel lengths only from known quality manufacturers like Colt, BCM, Noveske and maybe DD. I'm thinking maybe just one barrel of each length so that you know you are not seeing a difference in gas port sizes affecting the results.
Once you establish a good baseline for say, a 14.5" with carbine length gas, you could later test the "best" combo in different makes to compare an LMT, Colt, DD, BCM and Spikes all in 14.5".
Unless you narrow down the variables, the data will be hard to extrapolate into useful information due to an exponential number of variables. I'm really looking forward to seeing the results.
There have been a number of good ideas, including this one, and I'll take the weekend to formulate a "game plan", in order to get the most out of the videos.
Why the bounce with the 5.4oz 9mm buffer but no bounce with the 5.2 oz rifle buffer?
I believe the 9mm buffer doesn't have the internal floating tungsten weights like a rifle buffer does.
I was a bit surprised by that.
Seems that Specialized Armament was right when he said that granulated tungsten wouldn't work as well as tungsten slugs.
The difference isn't HUGE, but it's noticeable.
87, it almost looked like the H did better than the H2 in the Spike's upper. Did I see that right?
ETA: nevermind, just watched it again. They are surprisingly similar though.
Markm, can you provide a link to the information you're referring to?
87, it almost looked like the H did better than the H2 in the Spike's upper. Did I see that right?
ETA: nevermind, just watched it again. They are surprisingly similar though.
Markm, can you provide a link to the information you're referring to?
I believe MARKM is referring to this post:
http://www.weaponevolution.com/forum/showthread.php?2435-ST-T2-Heavy-Buffer-(by-Spikes-Tactical)&p=21889#post21889
By the way, the 9mm buffer body (6.3oz) with the 3oz of tungsten granules performed almost exactly like the standard 9mm buffer (5.4oz).
I think that the 9mm buffer body slamming against a barrel extension at speed X is going to hit with more gumption than the lighter carbine/H buffer body slamming against the barrel extension at speed X. And while the 3 steel weights in the carbine or 1 tungsten and 2 steel in the H and so on can counteract the force of the lighter body (with varying degrees of success), those 3 steel weights are wholly inadequate for counteracting the force of the heavier body. It would be much worse with the weights fixed in place.
Now, if there were 3 tungsten weights in the steel body...I may have to rig that up and give it a shot.
I'm told by an engineer friend that the steel weights may be "springier", so in addition to the tungsten weights having more mass, they also are less forgiving, which adds to their effectiveness.
Someone correct me if I'm wrong.
BufordTJustice
07-31-10, 03:15
By the way, the 9mm buffer body (6.3oz) with the 3oz of tungsten granules performed almost exactly like the standard 9mm buffer (5.4oz).
I think that the 9mm buffer body slamming against a barrel extension at speed X is going to hit with more gumption than the lighter carbine/H buffer body slamming against the barrel extension at speed X. And while the 3 steel weights in the carbine or 1 tungsten and 2 steel in the H and so on can counteract the force of the lighter body (with varying degrees of success), those 3 steel weights are wholly inadequate for counteracting the force of the heavier body. It would be much worse with the weights fixed in place.
Now, if there were 3 tungsten weights in the steel body...I may have to rig that up and give it a shot.
I'm told by an engineer friend that the steel weights may be "springier", so in addition to the tungsten weights having more mass, they also are less forgiving, which adds to their effectiveness.
Someone correct me if I'm wrong.
I do know that Tungsten is harder (and much more brittle) than steel, in addition to being more dense.
Ultra killer videos, by the way.
As if you need more requests....I do currently run a Spike's buffer (with green, rounded blackjack buffers tip/bumper) with a Spike's M16 FZ coated BCG and a tubbs flat-wire spring (Spike's lower w/ a BCM 16" middy upper). I'm terribly interested in seeing how the buffers would behave with a tubbs flat-wire spring like mine or a springco blue.red spring setup. All are SUPPOSED to increase pressure on the bolt in-battery and, in my mind, increase the force with which the bolt carrier group returns to battery. I'm just wondering if the increased spring pressure would reduce bolt-bounce or aggravate it.
Great thread, brother.
I believe MARKM is referring to this post:
http://www.weaponevolution.com/forum/showthread.php?2435-ST-T2-Heavy-Buffer-(by-Spikes-Tactical)&p=21889#post21889
That is correct. Thanks.
Thanks guys, that was an interesting read. Looking forward to more results on this.
87, one small request. If its not too much trouble, could you show two rounds fired with each combo in the videos? The one you did with the 5.45 upper was a little easier to compare. If it makes the vid too long & can't be done, I understand. Thanks for taking the time to do this, I think it could be one of your most informative tests completed to date. I'll be staying tuned.
Thanks guys, that was an interesting read. Looking forward to more results on this.
87, one small request. If its not too much trouble, could you show two rounds fired with each combo in the videos? The one you did with the 5.45 upper was a little easier to compare. If it makes the vid too long & can't be done, I understand. Thanks for taking the time to do this, I think it could be one of your most informative tests completed to date. I'll be staying tuned.
I may actually go to 3 shots. The third shot would show the bolt locking to the rear. Part of the reason why I have not done so is that I was literally out of 5.56/.223 other than Black Hills and Federal Bonded. I have been picking up boxes of crappy ammo for 40-50 cents a round at Dick's Balls and Sporting Goods. I have more ammo on the way, so that problem should be resolved. I also have more springs, buffers, and a BCM 20" upper being shipped.
So what conclusions can i draw from this test? should i remove my 9mm buffer that i have been running for a long time in my midlength and replace it with the car one that it came with? Don't really want to buy another buffer, but my eyes can't distinctly tell which actually performed all that much better.
So what conclusions can i draw from this test? should i remove my 9mm buffer that i have been running for a long time in my midlength and replace it with the car one that it came with? Don't really want to buy another buffer, but my eyes can't distinctly tell which actually performed all that much better.
If you feel as though you are performing to the best of your ability and your current equipment isn't holding you back, then don't change anything. Why would you?
If, however, you feel as though your equipment may be holding you back then finding the buffer/spring combination that best eliminates bolt-bounce may be important to you.
There is a third group of people that don't know what they don't know, and videos like this are informative to them and give them more of a knowledgebase from which to evaluate their equipment and choices. Maybe they put a 9mm buffer in a 5.56 gun thinking they knew what they were doing and watching these videos demonstrates to them that it was actually counter-productive.
That's what I'd take away from it if I was running a 9mm buffer in a 5.56 gun: not only is it not adding any benefit to the system but in fact is making things worse.
evolixsurf
07-31-10, 11:28
I believe this is the article you guys are looking for. This is a great read.
http://www.defensereview.com/the-big-m4-myth-fouling-caused-by-the-direct-impingement-gas-system-makes-the-m4-unreliable/
Thinking through this, I'm not really sure there's any issue with bolt bounce when running semi-auto unless there's insufficient spring pressure to ensure lockup after the bounce. My thoughts are that the bolt cycling and lockup are complete before the shooter releases the trigger to reset the trigger for the subsequent shot. And the amount of bounce we're seeing is very, very small.
Unless someone were so quick on the trigger that they're capable of shooting subsequent shot(s) during the rebound/bounce phase (and I don't think anyone is that quick), there's not any real issue. The bolt eventually locks up, even with bounce, prior to the time the trigger is reset and the subsequent shot is broken. Am I wrong?
Shooting full-auto would be a different story, here I can see where bounce gets in the way of breaking subsequent shots.
Thinking through this, I'm not really sure there's any issue with bolt bounce when running semi-auto unless there's insufficient spring pressure to ensure lockup after the bounce. My thoughts are that the bolt cycling and lockup are complete before the shooter releases the trigger to reset the disconnector for the subsequent shot.
Unless someone were so quick on the trigger that they're capable of shooting subsequent shot(s) during the rebound/bounce phase (and I don't think anyone is that quick), there's not any real issue. The bolt eventually locks up, even with bounce, prior to the time the subsequent shot is broken. Am I wrong?
Shooting full-auto would be a different story, here I can see where bounce gets in the way of breaking subsequent shots.
That's why I stated that the buffer weight is not as critical if the rest of the system is lubricated, clean, and all the springs are in good condition (and it's in semi auto). The weapon will function. But will it function at its best? That's what I'm trying to get at.
I don't want the level of bolt bounce seen in some of the clips, even if I never put the upper on a registered lower. And since heavier buffers have other benefits, beyond reducing/eliminating bolt bounce, I'll stick with them for all my ARs.
motorwerks
07-31-10, 12:28
for what its worth I have 2 ARs that are set up very close. One has Tubb flat wire spring and a Spikes buffer, the other has a normal Carbine buffer and spring, and it seems like the Flatwire/spikes stays on target much better. Everyone that shoots the two of them seems to like the FW/Spikes better.
The value of the proper H buffer works in both directions, literally. Slowing down the time it takes for your bolt to unlock and subsequently bolt group speed translates to reduced recoil and wear on your FCG parts.
Thanks for the informative videos, I learned a thing or two. At least one of them disproved some of my uninformed assumptions.
That's why I stated that the buffer weight is not as critical if the rest of the system is lubricated, clean, and all the springs are in good condition (and it's in semi auto). The weapon will function. But will it function at its best? That's what I'm trying to get at.
I don't want the level of bolt bounce seen in some of the clips, even if I never put the upper on a registered lower. And since heavier buffers have other benefits, beyond reducing/eliminating bolt bounce, I'll stick with them for all my ARs.
I can see how having a proper, in-spec buffer spring is important to reliable cycling, and I can see how a heavier buffer slows things down to improve cyclic reliability. But my takeaway from these videos is that it apears with a good spring, carrier/bolt bounce is really much ado about nothing. I could imagine with an out-of-spec spring, how things would be worse.
Do you have any BM uppers? Or any retired springs? It would be interesting to see the affects of gas port diameter and spring wear on carrier velocity and bounce. I'm curious the degree with which a larger port affects these aspects. Just a thought if you have access to one.
I believe this is the article you guys are looking for. This is a great read.
http://www.defensereview.com/the-big-m4-myth-fouling-caused-by-the-direct-impingement-gas-system-makes-the-m4-unreliable/
Here's the money quote from that article that is relevant to this discussion.
"The difference was that I used a heavier Sprinco buffer spring (correctly called an action spring), a DPMS Extra-heavy buffer (.2oz lighter than a Colt H3 buffer), and a 5 coil extractor spring with a Crane O-ring for added extractor tension. Those drop-in parts made my rifles obscenely reliable, and still do......With the abovementioned drop-in parts, the M4 is as reliable as any weapon I have ever fired, and I have fired probably every military-issue assault rifle fielded worldwide in the last 60 years as a Special Forces Weapons Sergeant (18B)."
Do you have any BM uppers? Or any retired springs? It would be interesting to see the affects of gas port diameter and spring wear on carrier velocity and bounce. I'm curious the degree with which a larger port affects these aspects. Just a thought if you have access to one.
You realize that these videos are A LOT of work to film, Edit down, and produce don't you? ;)
The possibility for test combos is nearly limitless. And for what it's worth the idea of limiting the additional wear on the bolt lugs and barrel extension by having the bolt stay locked when it closes is worth every bit the price of the correct buffer.
Bolt bounce could be a real pain in the ass on a dirty gun in combat. A filthy chamber or dry weapon could need a forward assist bump if the bolt group keeps popping out of battery slightly.
There's nothing appealing to me about bolt bounce, and it's an indication of a poorly set up weapon.
Here's the money quote from that article that is relevant to this discussion.
I love that article. Although I don't find the o-ring necessary, and am completely uncomfortable with aftermarket springs, I like the notion of having the right buffer and healthy springs... and MAGS.
You realize that these videos are A LOT of work to film, Edit down, and produce don't you? ;)
The possibility for test combos is nearly limitless. And for what it's worth the idea of limiting the additional wear on the bolt lugs and barrel extension by having the bolt stay locked when it closes is worth every bit the price of the correct buffer.
Bolt bounce could be a real pain in the ass on a dirty gun in combat. A filthy chamber or dry weapon could need a forward assist bump if the bolt group keeps popping out of battery slightly.
There's nothing appealing to me about bolt bounce, and it's an indication of a poorly set up weapon.
I do. It's easy for all of us who get the benefit of viewing these for free to come up with other follow-on tests, we don't have to take the time to conduct them or fund them.;) It's not meant to criticize the original work, it's just that after seeing these combos and how little delta there is between setups, what the next phase of testing might reveal. Call the first version 1.0 and the follow-on version 2.0.
Your point about additional bolt lug wear, it's not clear to me that these videos show any bolt unlocking. Looks to me like we're seeing carrier bounce, but it doesn't look to me like the degree of bounce is enough to cause subsequent unlocking. After my earlier post I played with a carrier and bolt, and I had to move the carrier what I felt was a greater distance than what I observed in the videos, before the cam pin began rotating the bolt. I'm surmising that in all videos the bolt locks into position at the first seating of the carrier and there's no subsequent bolt unlocking based on the limited degree of bounce observed. But I could be wrong, I'm just guessing.
Your point about filthy guns in combat goes more to the point of keeping your weapon lubed and clean rather than whether or not you choose the optimum buffer. And also making sure your buffer spring is of the proper, in-spec length.
very very interesting... seems the rifle is the best... ;)
littlejerry
07-31-10, 18:59
Thanks for posting the videos- they are extremely informative.
As an engineer who has studied the basics of mass/spring/damper system dynamics it seems to me like you could model the AR system pretty accurately with some real-world test data to truly find the "ideal" buffer weight and buffer spring rate.
Its rather frustrating to see how un-optimized a 40 year old rifle is.
motorwerks
07-31-10, 19:10
maybe I missed something (even though I have been following this since the beginning) whats the big deal with bounce?
Your point about additional bolt lug wear, it's not clear to me that these videos show any bolt unlocking. Looks to me like we're seeing carrier bounce, but it doesn't look to me like the degree of bounce is enough to cause subsequent unlocking.
The bolt rotates against the barrel extension at the very first rearward movement of the carrier. Even though the bolt isn't coming out of the extension, it's wearing on it in its rotation. Wear on the bolt lugs and barrel extension are what cause headspace "growth" on the AR.
Negligible? maybe... But over thousands of rounds it could add up to additional wear.
very very interesting... seems the rifle is the best... ;)
Indeed. And the reason I've run an 11.5" SBR with an A1 rifle buttstock/buffer for my home defense gun for years. It's an odd combo, but runs very good.
The bolt rotates against the barrel extension at the very first rearward movement of the carrier. Even though the bolt isn't coming out of the extension, it's wearing on it in its rotation. Wear on the bolt lugs and barrel extension are what cause headspace "growth" on the AR.
Negligible? maybe... But over thousands of rounds it could add up to additional wear.
A couple of comments. I may be off base, but I don't think the bolt rotates "at the very first rearward movement of the carrier". I see two gaps that have to be overcome prior to the bolt starting to rotate. First, from the rear face of the cam pin to the box section portion of the upper that the cam pin eventually bears against. I'm assuming this gap is at least a couple hundreths of an inch, maybe more. Second, the cam pin tracks along the slot in the carrier for a bit before it hits the portion that forces rotation. Combined, these gaps could total more than the degree of bounce we're seeing, and if so, I wouldn't think any bolt rotation would occur.
Second, even if the lugs rotate a smidge, they aren't loaded anything like they would be during the extraction phase, so I'd guess that the measurable wear seen on bolts are from the highly loaded extraction phase, not the bolt bounce phase.
Again, this is just an academic discussion, at least from my perspective. As the OP pointed out, there are other factors to consider regarding weapon reliability, and bolt bounce is only one of them. I must say though that I've been aware of the bolt bounce phenomenon from reading past threads on the subject, but I always pictured in my mind that it was significantly worse than what we're seeing on these videos. If this degree of bounce is representative of "troublesome" bounce, then it goes to show how sensitive the weapon system really is to ammo pressure level, spring rate and buffer weight.
I may have missed it, but are these Auto carriers or Semi?
Great videos. Thanks.
Jeremy.
I may have missed it, but are these Auto carriers or Semi?
Great videos. Thanks.
Jeremy.
The 420fps video shows an AR-15 carrier. The 1000fps videos all show M16 carrier equipped weapons.
If this degree of bounce is representative of "troublesome" bounce, then it goes to show how sensitive the weapon system really is to ammo pressure level, spring rate and buffer weight.
This is what I'd call troublesome bounce -
http://www.youtube.com/watch?v=y2GeugjmeF0
As I will show in future videos, buffer weight also affects other things. Hopefully I'll get some suppressed videos this morning.
Please do take also some videos of gas piston AR (you have SR556?) with different buffers/springs. It would be interesting to see if same rules apply here.
Thomas M-4
08-03-10, 13:05
Great thread glad some one did a slow motion comparison between standard heavy buffer types and the spikes tactical. I know markm is also. I hope you keep it up I would like to see some tests with buffer spring rates would be great. I feel that the stiffer springs that are on the market also contribute to the bolt bounce. As you video shows the rifle buffer and spring control the bolt carrier better than the carbine system hmm heavy buffer and less spring rate.[ BLUE'S CLUE] Other's that have been praising stiffer buffer springs and st-2 buffers look to be on the wrong track.
Heavy Metal MGI buffer looks to be very interesting concept also.
Please do take also some videos of gas piston AR (you have SR556?) with different buffers/springs. It would be interesting to see if same rules apply here.
Bounce with lighter carriers and little to none with an H2. That's setting 2. Setting 1, short stroking with all ammunition and buffers. Setting 3, more bounce. I'll splice together the video later.
I have a comparison of the recoil of a BCM midlength and the SR556 here. (http://www.youtube.com/watch?v=pQqhR-bUfaU)
Great thread glad some one did a slow motion comparison between standard heavy buffer types and the spikes tactical. I know markm is also. I hope you keep it up I would like to see some tests with buffer spring rates would be great. I feel that the stiffer springs that are on the market also contribute to the bolt bounce. As you video shows the rifle buffer and spring control the bolt carrier better than the carbine system hmm heavy buffer and less spring rate.[ BLUE'S CLUE] Other's that have been praising stiffer buffer springs and st-2 buffers look to be on the wrong track.
Heavy Metal MGI buffer looks to be very interesting concept also.
I think the "better" action springs will do "better" than you think - but we'll see.
Thomas M-4
08-03-10, 17:53
Bounce with lighter carriers and little to none with an H2. That's setting 2. Setting 1, short stroking with all ammunition and buffers. Setting 3, more bounce. I'll splice together the video later.
I have a comparison of the recoil of a BCM midlength and the SR556 here. (http://www.youtube.com/watch?v=pQqhR-bUfaU)
I think the "better" action springs will do "better" than you think - but we'll see.
What do you mean by better?
If by material choices CS VS SS . I have my suspicion which one will do better but just thinking the difference might be to small to even notice with slow motion. Maybe I am wrong wont be the first time.
Hope you can find a measurable difference none the less.
Bounce comes from something hitting something else. A shockwave is sent through the parts and the energy causes them to bounce apart. Then the parts come together and hit again causing another smaller shockwave.
I'm not an AR expert but the logical conclusion is the bolt bounces when the buffer is unable to absorb and dissipate the energy from the shockwave. Parts subjected to shockwaves can peen, flex and crack at stress points. Take a steel hammer and beat on another piece of hardened metal. The hammer will bounce. A deadblow hammer is designed to absorb and dissipate the shockwaves imparted by the impact and does not bounce.
The BCG is a reciprocating part. It goes from zero (round in chamber bolt closed) to pretty dang fast (round fires bolt opens), to zero (Bolt all the way to the rear) to pretty dang fast (bolt closes) to zero (fresh round chambered bolt closed) all in a short time in a short space with each shot. With bounce, the BCG does all of that again on a smaller scale.
Maybe in the grand scheme of things, this bounce means very little. But I think an AR tuned to eliminate the bounce will have a smoother recoil impulse, faster recovery and be a bit more reliable. At the very least, it's one less variable.
It's also known that spring rate and mass must be matched to the job
The bolt rotates against the barrel extension at the very first rearward movement of the carrier. Even though the bolt isn't coming out of the extension, it's wearing on it in its rotation. Wear on the bolt lugs and barrel extension are what cause headspace "growth" on the AR.
Negligible? maybe... But over thousands of rounds it could add up to additional wear.
No it doesn't. Look at the shape of the cam pin slot in your carrier. Bolt rotation does not start immediately.
The carrier has to travel a short distance rearward before the cam pin hits the diagonal face of the slot. Up until that point the cam pin is tracking along the straight edge, and during this phase the bolt remains locked up w/o any rotation -- only the carrier is moving. Bolt rotation/unlocking doesn't begin until the cam pin tracks across the diagonal portion of the slot.
OK buffer gurus, I've been attempting to test a few different buffer & spring combos in my SR15 E3 and I wanted to share some results with you guys to see what you think. Here's what I have tried so far:
Ammo used was Centurion .223 unless noted otherwise. I used this ammo because it is known to be underpowered. I am cheap and usually shoot .223 ammo at the range due to the cost savings over 5.56 ammo.
BCM CAR action spring + BCM CAR buffer (3.0 oz confirmed weight)*
- 100% function
- ejection normal at approx. 3 o'clock
*this combo will be the "control" for this experiment
BCM CAR spring + BCM H buffer (3.8 oz. confirmed weight)
- 100% function
- ejection at about 1:00
- extremely soft recoil
Tubbs flatwire action spring + BCM CAR buffer
- 100% function
- ejection at 2:00 - 3:00
- possibly softer recoil than the control group. Not a marked difference
Tubbs flatwire action spring + BCM H buffer
- will not lock back & caused short stroking
-cycled approx. 50% of the time
-ejection at approx. 1:00
- definitely a no-go for my SR15
Tubbs flatwire action spring + Daniel Defense T2 buffer
-tungsten media, downloaded to 3.0 oz.
- would lock back approx. 50% of the time & caused short stroking
-cycled approx. 70% of the time
-ejection at approx. 2:00
- definitely a no-go for my SR15
-Wolf ammo resulted in a single shot rifle
I did not test the T2 buffer at full weight due to the H buffer's performance. I anticipated that the additional weight would induce malfunctions due to the H buffer's weak ejection.
The felt recoil when using the H buffer and standard carbine spring was fantastic. However, the forward ejection pattern concerned me. I have never really paid much attention to ejection patterns, primarily because all my rifles have reliably spit brass to 3:00 - 4:00.
Now that I have started this little experiment, I have a question. What does the forward ejection pattern indicate? Could that indicate that the gun is near shortstroking? I really liked the recoil characteristics of this set up. However, I want the rifle to be 100% reliable with quality .223 ammo. Am I risking being more prone malfuntion if the rifle is ejecting brass forward?
Thanks for taking the time to shoot, edit and post the video--VERY informative...
Prior to seeing this thread I had already ordered an H2 from Palmetto. It's going in my M&P 15. I just received it today so I weighed it.
Factory M&P Carbine buffer 2.96oz
Palmetto State Armory H2 4.62oz
That is a fairly substantial difference. I'm taking it to the range tomorrow. Not to stray but is Spikes making the body of the buffers for Palmetto? It's a great looking piece no doubt!
Great thread!!! It's nice to have some of the mystery removed. I had made my choice and this leaves me more confident. I have Wolf Mil Classic and IMI M193 to try out. No Hi Speed cam though.;)
BufordTJustice
08-05-10, 16:20
mtdawg169,
I am currently running a BCM 16" middy upper over a spike's lower. I'm using a tubbs flat-wire buffer spring w/ an ST-T2 buffer (H2 buffer being shipped from Grant as I type this ;) ). I'm running great right now. I'll report if my setup will run with the tubbs flat wire and the H2 (that's my goal).
If not, I'm gonna try the H2 and a blue springco CS buffer spring. It appears buffer weight affects recoil characteristics more than spring strength (as long as the spring is adequately strong to begin with). I wonder if a Springco red spring or the tubbs would induce MORE bolt bounce upon return to battery than a normal buffer spring? Or if the added spring strength reduces bolt bounce? Or maybe ti doesn't affect bolt bounce at all....:confused:
mtdawg169,
I am currently running a BCM 16" middy upper over a spike's lower. I'm using a tubbs flat-wire buffer spring w/ an ST-T2 buffer (H2 buffer being shipped from Grant as I type this ;) ). I'm running great right now. I'll report if my setup will run with the tubbs flat wire and the H2 (that's my goal).
If not, I'm gonna try the H2 and a blue springco CS buffer spring. It appears buffer weight affects recoil characteristics more than spring strength (as long as the spring is adequately strong to begin with). I wonder if a Springco red spring or the tubbs would induce MORE bolt bounce upon return to battery than a normal buffer spring? Or if the added spring strength reduces bolt bounce? Or maybe ti doesn't affect bolt bounce at all....:confused:
Thanks BufordT. I have run the T2 buffer with flatwire spring in my Noveske middie upper and it is a dream to shoot.
The test above was performed with a Knight's SR15 E3, which is supposed to be run with a CAR buffer due to the longer gas system length. It is a soft shooting gun right out of the box. I just wanted to see how far it could be pushed and still remain reliable and at the same time, see if I could make it shoot even softer.
I'm really interested in 87GN's tests to see what effect the different springs might have on bolt bounce.
I love that article. Although I don't find the o-ring necessary, and am completely uncomfortable with aftermarket springs, I like the notion of having the right buffer and healthy springs... and MAGS.
Excellent. Yes, approach aftermarket springs with extreme prejudice. It is a rare case they are as good or better than USGI (unless they are made to USGI specs). In fact, show me ONE aftermarket spring better than any spring in an M4.
Extractor spring - nope.
Magazine spring - nope.
Action spring - nope.
The AR action spring is not undersigned and so I would not be looking to flat wire. A 1911 recoil spring is underdesigned, and normally I would look at flat-wire for that, but there is no room to make the wire wider. Guess what - the AR has the same issue. Because the AR action spring needs to be 0.073 MAX diam, a flat wire spring is only THINNER in one direction.
The USGI 17-7 action spring only has about a 30% stress/strain ratio. That means it can last a looong time. 15,000+ rounds should not be a problem. I would be more concerned about a flat-wire spring breaking.
Very interesting thread, seems that just because the platform is modular doesn't mean that just any combo of parts will run reliably.
BufordTJustice
08-06-10, 00:51
Thanks BufordT. I have run the T2 buffer with flatwire spring in my Noveske middie upper and it is a dream to shoot.
The test above was performed with a Knight's SR15 E3, which is supposed to be run with a CAR buffer due to the longer gas system length. It is a soft shooting gun right out of the box. I just wanted to see how far it could be pushed and still remain reliable and at the same time, see if I could make it shoot even softer.
I'm really interested in 87GN's tests to see what effect the different springs might have on bolt bounce.
I agree. I wanna run as much spring as I can. I am a little frustrated by the video showing the Spike's ST-T2 buffer in the BCM 16" middy showing more bounce than the supposedly lighter standard H-buffer. My goal is to run an H2 in my setup...if I can do that and use the tubbs spring, sweet deal. I'm hoping my Fail Zero BCG's smoothness and lack of friction during operation will help me reach my goal. However, I have ordered a Blue Springco spring for use with the H2 in the case that the Tubbs + H2 won't work (I'm thinking, despite my wishes, that the tubbs +H2 will be too much for my BCM 16" middy). We shall see.
I expect it to run using 5.56mm ammo (I use BVAC 5.56mm 75 grain tac loads using the 75 grain Hornady TAP bullet), but also require that it run using .223 ammo. Haven't read about anybody with this same setup, so I'll be sure to post my findings...it's gonna beat least a week till I get to the range. :(
As for 87GN's tests, this has to be the coolest thread I've read in the last 6 months. Kudos, brother. :)
As for KAC, the SR15 is pretty much optimized from the git-go, so tinkering really doesn't gain us much on the SR15 as it does on lesser designs. But we are all after the same thing...the softest shooting yet-still-reliable possible.
I love that article. Although I don't find the o-ring necessary, and am completely uncomfortable with aftermarket springs, I like the notion of having the right buffer and healthy springs... and MAGS.
Excellent. Yes, approach aftermarket springs with extreme prejudice. It is a rare case they are as good or better than USGI (unless they are made to USGI specs). In fact, show me ONE aftermarket spring better than any spring in an M4.
Extractor spring - nope.
Magazine spring - nope.
Action spring - nope.
The AR action spring is not undersigned and so I would not be looking to flat wire. A 1911 recoil spring is underdesigned, and normally I would look at flat-wire for that, but there is no room to make the wire wider. Guess what - the AR has the same issue. Because the AR action spring needs to be 0.073 MAX diam, a flat wire spring is only THINNER in one direction.
The USGI 17-7 action spring only has about a 30% stress/strain ratio. That means it can last a looong time. 15,000+ rounds should not be a problem. I would be more concerned about a flat-wire spring breaking.
Aftermarket springs are a profit center for the manufacturer, plain and simple. Current spec USGI springs have over fifty years of hard use to validate their effectiveness.
Anyone who has chimed in with a "I run this spring with this buffer" is a statistical sample of one. Qualifying your comment with "and it shoots like a dream" is overly subjective.
If you monkey with springs and buffers, in addition to checking for bounce, also make sure your cyclic rate is at least 700 rpm. If you want it to do better when dirty, try for 750-800.
Anyone who has chimed in with a "I run this spring with this buffer" is a statistical sample of one. Qualifying your comment with "and it shoots like a dream" is overly subjective.
Well, I guess I'm your "anyone". I apologize if I offended your sensibilities, but there is no reason to get in a twist just because I offerered up an example. In fact, my post was meant to clarify that Buford T's advice was not really pertinent based on the fact that he was discussing a middie and my little experiment was on an SR15. My comments about the flat spring & T2 buffer combination were pointed out only because of the similarity between what BufordT was running on his BCM middie and what I run on my Noveske middie. I'm not saying that it would work for everyone or that it is even necessary. But it does work well for me in that particular rifle. I don't have enough rounds on it to determine if it is just as good as a standard spring, but I intend to run it over the long haul to find out. The honest truth is that I thnk the spring is probably the smallest part of the equation and makes little difference as long as it is in good condition.
I have made no claims that a flat wire spring is better than a standard USGI spring or anything of the sort. However, I am running one in one of my rifles. That rifle, through a combination of gas system length, buffer, spring & muzzle device, shoots very well. It has a very soft recoil impulse, has never had a malfuntion of any kind and shoots very flat. I don't subscribe to the idea that it is because of a "wonder spring". It would probably shoot just as well with a USGI spring. However, when I put that setup together, I didnt have one on hand. So the Tubbs spring that was sitting in my parts box went in and it has performed well for roughly 2,000 rounds. It may be a statistical sample of one, but it is still a data point for reference and and it is based on factual first-hand experience. Take it for what it's worth. I wouldn't expect anyone to read that post and think that it would work for everyone under every circumstance. When an end user starts fiddling with how the system operates, they have to be aware that just because some stranger on the internet said it worked well for them, it doesn't mean that it is the Gospel truth for everyone. I have been experimenting with buffers and springs over the last couple of weeks out of curiosity, but my go-to rifle has a standard CAR spring and CAR buffer because I know it's proven and it works.
If you monkey with springs and buffers, in addition to checking for bounce, also make sure your cyclic rate is at least 700 rpm. If you want it to do better when dirty, try for 750-800.
Robert, is there any way to check for bounce withoout the use of a high speed camera? How can the average person quantify something like this as well as cyclic rate on a semi AR?
I can't think of a way without high speed video.
For cyclic rate, high speed video or try it on someone's FA lower.
For the record, I have never seen bolt bounce on high speed video before these posts.
I have a 300 Fireball upper with an H2 buffer and no bounce. Also no bounce with an HK-416 buffer.
How are the videos coming 87? Looking forward to seeing the results!
It has been going quite well, thank you.
I have spent several hours each day for the past two weeks at the range...and I haven't really begun to do anything approaching a proper test.
I have a massive amount of footage that I am trying to sew together for now. I've learned quite a bit, I learn more each and every time I watch a video clip. For example, I was given a large number of reloads by a dealer that turned out to not be sized properly. They functioned OK in the BCMs, but no carrier bounce was evident with any buffer or spring combination. I figured out that the bolt wouldn't begin to unlock just from "carrier bounce momentum" alone. So I started using those rounds for other purposes.
motorwerks
08-09-10, 17:42
I just had a thought....
Are these guns locked down in a sled or something?
Could shoulder firing absorb some of this and lessen it, like a shock absorber?
I just had a thought....
Are these guns locked down in a sled or something?
Could shoulder firing absorb some of this and lessen it, like a shock absorber?
I've built a device to hold the weapons steady during firing. None of the videos posted so far show it.
BufordTJustice
08-09-10, 17:53
Dude, seriously.
87, you're creating such an amazing resource with these videos. I'd say once you finish the sled and settle on your buffer and spring combinations, you should create a new thread with a master post cuz, IMHO, this is SERIOUS STICKY MATERIAL.
Thank you, sir, for your hard work and your time. The videos are AR15 mythbusters. We have been enlightened.
Keep up the great work.
Mike Miller
08-10-10, 09:13
Thank you for all of your hard work and time you have invested in this.
motorwerks
08-10-10, 13:58
I've built a device to hold the weapons steady during firing. None of the videos posted so far show it.
I still have to wonder if when the BCG runs home and into battery while being shouldered, if maybe the body absorbs shock and the BCG doesn't bounce or if it does maybe not as much. Because I know I'm not bionic and I cant see superslowmo at 1000fps but I can hold my rifles and when I let the bolt go the rifle jerks forward a little. That may be the rifle going forward, instead of the BCG bouncing. It seems like basic physics Keep in mind BASIC is about the extent of my physics knowledge. I am not trying to be a butthole here, just throwing out something thats been on my mind about this topic. Like I would like to see a comparison of hand held v locked down.
Maybe I watch to much mythbusters?? :blink:
There's something wrong with my rifle! There's a big hole in it!
http://www.545ar.com/tubecutaway2.jpg
Thomas M-4
08-17-10, 17:36
There's something wrong with my rifle! There's a big hole in it!
http://www.545ar.com/tubecutaway2.jpg
:blink:
OK a little slow today I think I see what you are doing.
I hope its burr free inside the buffer tube.
:blink:
OK a little slow today I think I see what you are doing.
I hope its burr free inside the buffer tube.
It was "burr-free" enough. That was a quick hack job with a 3/8" drill bit so I could get to the range before it closed at the new time of 2:30. :rolleyes:
BufordTJustice
08-17-10, 19:15
Awesome. Can't wait to see the results!
Man you have gone above and beyond the call lol!
A rest like a lead sled with a velcro strap to hold down the rifle might be handy as well.
+1
This is really interesting already, but for it to be really "scientific," then eliminating the variable of the guy holding the gun is important...
I was all set to buy a ST-T2. Forget that.
Bimmer
BufordTJustice
08-17-10, 21:55
+1
This is really interesting already, but for it to be really "scientific," then eliminating the variable of the guy holding the gun is important...
I was all set to buy a ST-T2. Forget that.
Bimmer
Yeah. I immediately substituted an H2 from G&R in place of the ST-T2 I was running. There is no excuse for the bolt-bounce I saw in the vids. I've got an H3 on the way for testing. A couple other guys are doing the same....i'm sure an update on the H3 using cheap (read: Russian) ammo will be coming soon from one of us. At least until 87 films/edits/uploads some more of his killer videos.
BufordTJustice
08-17-10, 23:28
I just stumbled on to this website. There are some awfully heavy buffers available there.....anybody use them or know anybody who does?
http://www.heavybuffers.com/ar15carbine.html
Overheated the camera, wasn't able to get the footage I needed, yesterday or today. Will try again tomorrow.
BufordTJustice
08-18-10, 23:55
Overheated the camera, wasn't able to get the footage I needed, yesterday or today. Will try again tomorrow.
That sucks. If you don't mind me asking, what camera/lens are you using?
That sucks. If you don't mind me asking, what camera/lens are you using?
My bet goes to one of Casio Exilim High Speed line of cameras :rolleyes:
fivefivesix
12-10-10, 11:04
please exuse my ignorance but would a heavier buffer create an issue if i fire mostly wolf ssteel cased ammo, my problem i was having was there was not enough ooommph to send the bcg back far enough to strip the next round from the mag. ive replace my action spring and it now cycles it reliably.
The only way to know what buffer to use for a unique ammo and gun combination, is to measure either the bolt velocity or cyclic rate of fire with your gun and your ammo. If your brass is not ejecting or not ejecting far enough than it is likely your buffer is too heavy.
I'm currently working on a spreadsheet with ammunition, buffer, spring, and gas port diameter/gas sytem length/barrel length as factors and carrier velocity and rate of fire as results...will probably try to turn it into a graph. I've come to some interesting (abnormal) findings and need to verify them before publishing.
I've been wondering how this was going. Looking forward to your results.
Sent from my Droid using Tapatalk
magikbullet
12-10-10, 23:54
this has been really interesting from the start, I look forward to seeing the spreadsheet 87gn!
:cool:
mutterranch
12-19-10, 18:16
Very Interesting...
Thanks
tag for later.
I'm currently working on a spreadsheet with ammunition, buffer, spring, and gas port diameter/gas sytem length/barrel length as factors and carrier velocity and rate of fire as results...will probably try to turn it into a graph. I've come to some interesting (abnormal) findings and need to verify them before publishing.
I'd be happy to review the spreadsheet data for you.
87GN: Thanks for all your work on this. I have a few buffers and only used function as a test for whats better. This definatly puts things into perspective and has me rethinking my Spikes T2 and CAR spring combo. I have a thermal camera but not a high speed camera unfortunatly.
If you need any specific buffer to test with and dont have it let me know and ill see if i have one you can borrow for the test. If you really feel like complicating things i have a Tubb carrier weight as well. I also have a spare tubb flatwire spring.
Heavy Metal
12-23-10, 21:33
You guys need to remember that a Buffer does two jobs. First, it is part of the total recoiling mass, second, it is a ...well....buffer...
It can excell at the former and fail at the latter. The first affects the bolt velocity, the second the anti-bounce characteristics.
Using your HS video and your database of stoppages, have you been able to correlate how much bolt bounce needs to occur before stoppages ensue?
Using your HS video and your database of stoppages, have you been able to correlate how much bolt bounce needs to occur before stoppages ensue?
The answer to that is pretty complicated. If a malfunction were to occur as a result of bolt bounce, the weapon would probably malfunction in other ways before a malfunction occurred specifically due to bolt bounce. That is to say, bolt bounce so extreme that it might cause a malfunction is indicative of a very poorly set up weapon.
Of course this all changes on full auto, or perhaps when bump firing, because there is only about 12 ms between initial impact of the bolt carrier against the barrel extension and the initial rearward movement of the bolt carrier after the hammer falls on the new primer. So I think you can understand that if you had bolt bounce lasting 40 ms, you would definitely have problems on full auto. That is an extreme example, but I have witnessed it on several occasions, and regularly see bolt bounce over 12 ms with certain setups.
El Pistolero
12-25-10, 16:28
Great video, thanks for posting.
I run a BCM H2 buffer in my rifle and haven't had any problems.
87, Do you have access to cans? I'd like to see this done running it suppressed.
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