View Full Version : Help with A5 buffer choice
I know I know, it’s another A5 buffer thread. I searched and can’t find any answers to my specific quandary.
I have a 16” middy w/ Odinworks Ultralight barrel and SLR Sentry agb. Has a Sionics M16 bcg.
I want to try the A5 system, so I ordered the Green Spring from Sprinco. Looking at BCM kit, comes with A5H0 buffer. Is this the better option for a starting point for me than the A5H2 which is normally supplied with the VLTOR kit? If anyone has experience along these lines, please do help me out with some advice before I place my order
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Honestly it's best to have an assortment of A5 buffers so you can dial in a system on a new rifle, or re-tune your gun if you change something.
Search for tungsten buffer weights. Buy four, this will give you the ability to add weight to your buffer.
A5 extended length buffer configurations/weights;
H0, 3.8oz, four steel
H1, 4.56oz, one tungsten, three steel
H2, 5.33oz, two tungsten, two steel, (original/standard A5)
H3, 6.08oz, three tungsten, one steel
H4, 6.83oz, four tungsten
**Or, if you have a few carbine buffers, order the A4H4 buffer she replace tungsten weights with steel to lower the weight
Thanks guys. Are the tungsten weights on eBay gtg, or do I have to order from KAK or Geiselle?
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F263957462094
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I ordered mine from KAK, however eBay should be just fine as long as you order from a well rated seller
I guess I’ll just order from KAK and pay a couple of extra dollars for piece of mind.
I wonder why BCM sends the H0 buffer with the kit instead of the H2
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I guess I’ll just order from KAK and pay a couple of extra dollars for piece of mind.
I wonder why BCM sends the H0 buffer with the kit instead of the H2
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It’s cheaper. The H0 does not have any tungsten weights in it
...I wonder why BCM sends the H0 buffer with the kit instead of the H2
The A5H0 is cheaper and the H2 is harder to keep in stock. The A5H0 is about the same weight as a carbine H buffer. The A5H1 about the same as an H2 and the A5H2 is about the same as a rifle buffer.
Thanks so it seems the A5H0 and some tungsten weights is the way to go, covers all bases and cost efficient
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H2 on any gun other than the 14.5 BCM middy. From there, I correct the gas somehow. Running blow hole barrels with over-weight buffers isn't acceptable to me anymore.
The default A5 buffer is the A5H2. That's per Vltor, who engineered the system. BCM specs the H0, maybe to guarantee function with a 14.5" middy. Being cheaper doesn't hurt, either.
Sprinco green isn't the best for the A5H2 and lighter. Milspec rifle spring is preferable here.
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vicious_cb
12-12-18, 15:17
Without knowing the gas port size of the Odin barrel its a moot point trying to recommend an A5 buffer weight.
BCM's gas port sizes are known and on the smaller size for midlengths. I can tell you right now there are few companies that follow BCM's philosophy of smaller gas port sizes.
The default A5 buffer is the A5H2. That's per Vltor, who engineered the system. BCM specs the H0, maybe to guarantee function with a 14.5" middy. Being cheaper doesn't hurt, either.
Sprinco green isn't the best for the A5H2 and lighter. Milspec rifle spring is preferable here.
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Dangit I already ordered the green spring and from what I’ve read on other threads, and it says on Sprincos description it works with that buffer. Did I waste the money?
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vicious_cb
12-12-18, 15:25
Dangit I already ordered the green spring and from what I’ve read on other threads, and it says on Sprincos description it works with that buffer. Did I waste the money?
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No, the stiffer spring would only be a concern if the Odin's gas port was on the smaller end and I highly doubt that. Im going to guess that the Odin barrel's gas ports are f***ing huge and you could probably run an A5H2 or heavier. Again BCMs are on the small end of gas ports so they spec lighter springs and lighter buffers.
Without knowing the gas port size of the Odin barrel its a moot point trying to recommend an A5 buffer weight.
BCM's gas port sizes are known and on the smaller size for midlengths. I can tell you right now there are few companies that follow BCM's philosophy of smaller gas port sizes.
The gas port size is moot since I have a SLR agb though isn’t it? Following the logic here, I’m starting to grasp that less gas requires less spring and less buffer weight. Am I on the right track for tuning my AR? It’s been boringly reliable to date, and It’s high time to $&@% with it a bit
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An adjustable gas block only adjusts one way: down, by constricting the flow from the port. You can’t get more gas than the port allows, just like you can’t put a contraption on your water hose and expect more water than the spigot sends.
Adjustable gas blocks are designed to either fix a port there too big or to reduce gas when suppressed. If you aren’t in that situation, I would use a standard gas block.
I have A5 on several rifles from HO to H3 without an adj gas block.
Rayrevolver
12-12-18, 16:51
Search for tungsten buffer weights. Buy four, this will give you the ability to add weight to your buffer.
A5 extended length buffer configurations/weights;
H0, 3.8oz, four steel
H1, 4.56oz, one tungsten, three steel
H2, 5.33oz, two tungsten, two steel, (original/standard A5)
H3, 6.08oz, three tungsten, one steel
H4, 6.83oz, four tungsten
**Or, if you have a few carbine buffers, order the A4H4 buffer she replace tungsten weights with steel to lower the weight
Someone can correct me, but I think only the A5H4 comes with a tungsten buffer weight that has a notch for the spring inside the weight itself. It might be cheaper to buy an A5H4 and then find steel weights to bring it down to a A5H1. Not sure the spring can be held in place by the notch in the rubber bumper part by itself. I found this out the hard way and limited any A5H2 buffer to max out at A5H3s, and left the steel weight/spring in place.
See the top buffer, furthest weight on the left:
http://i265.photobucket.com/albums/ii202/akula_88/long/6ad3488f.jpg
The gas port size is moot since I have a SLR agb though isn’t it? Following the logic here, I’m starting to grasp that less gas requires less spring and less buffer weight. Am I on the right track for tuning my AR? It’s been boringly reliable to date, and It’s high time to $&@% with it a bit
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Maybe not so moot if the barrel port is on the small side. Wide open is limited by the port diameter. I only have one A5 setup bought from Vltor that shipped with the 2 buffer. It shot fine but I turned a couple of steel weights to make it a zero. I cannot tell the difference. BCM plays it safe selling the kit with the zero. If you want to play with what may or may not get you killed it's on you. Can't blame them a bit. Nothing to do with being cheaper IMO. It's about working in all applications.
The gas port on my barrel is .750 and I run it with the gas block 7 clicks open. So I have plenty of extra gas I’m not using to cycle the gun. I have an H2 buffer and carbine tube currently. I just want to try the A5 setup and see how flat this gun can run with a mil-spec auto bolt carrier. It’s a very light rifle also, if that matters in the calculations
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Someone can correct me, but I think only the A5H4 comes with a tungsten buffer weight that has a notch for the spring inside the weight itself. It might be cheaper to buy an A5H4 and then find steel weights to bring it down to a A5H1. Not sure the spring can be held in place by the notch in the rubber bumper part by itself. I found this out the hard way and limited any A5H2 buffer to max out at A5H3s, and left the steel weight/spring in place.
See the top buffer, furthest weight on the left:
http://i265.photobucket.com/albums/ii202/akula_88/long/6ad3488f.jpg
Drill a hole about 3/16” deep in a tungsten weight. :D
Drill a hole about 3/16” deep in a tungsten weight. :D
[emoji33]
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To the OP: You are probably going to have a well functioning rifle with the "0" A5 buffer with the gas block opened up all the way. Try it with single round in a few mags, using 223 ammo, to see if it locks back on empty. Since you have an AGB, use it to reduce gas flow to the bolt carrier per the manufacturer's instructions. Once you find the point of failure to lock bolt back on empty, open the gas flow to where it last functioned well and add a click for reliability when dirty and call it good.
I have a 16" intermediate gas length barrel with an SLR AGB and A5 buffer and RE. Runs 100% even on PMC 223 ammo with all steel weights in buffer, "0", gas block opened 5 clicks from closed. Just make sure gas block is secure on barrel. I use high temp locktite, normal strength. If gassed right, the "0" A5 buffer has enough recipricating weight for reliabiity. Do not think the green spring will hurt, since its function in to close the action. So long as enough gas is allowed to enter the BCG for the spring to compress and allow the bolt to lock open on empty, a bit of extra push forward will not hurt reliability, only help it.
Mark
The gas port size is moot since I have a SLR agb though isn’t it? Following the logic here, I’m starting to grasp that less gas requires less spring and less buffer weight. Am I on the right track for tuning my AR? It’s been boringly reliable to date, and It’s high time to $&@% with it a bit
You want the right size gas port so you can run the proper buffer weight & spring rate.
Dangit I already ordered the green spring and from what I’ve read on other threads, and it says on Sprincos description it works with that buffer. Did I waste the money?
I like the A5 better with the green spring than a standard rifle spring.
What are you trying to fix or accomplish with a different spring and buffer?
I can tell you from running an A5 off and on since 2011 that it's not going to do much of anything on a 16" mid other than make recoil feel clunky and slow. It makes an overgassed gun kick harder.
H0 should work perfectly with that setup. I'd use a Tubbs flatwire spring too.
What are you trying to fix or accomplish with a different spring and buffer?
I can tell you from running an A5 off and on since 2011 that it's not going to do much of anything on a 16" mid other than make recoil feel clunky and slow. It makes an overgassed gun kick harder.
I think you're the only person that I've heard say that.
vicious_cb
12-12-18, 23:02
What are you trying to fix or accomplish with a different spring and buffer?
I can tell you from running an A5 off and on since 2011 that it's not going to do much of anything on a 16" mid other than make recoil feel clunky and slow. It makes an overgassed gun kick harder.
Those 2 statements are also completely contradictory.
If people subjectively prefer the Sprinco green for whatever reason, that's fine. Rock on. I think that some might not understand the difference it makes in the buffer system and how it has both pros and cons.
The Sprinco green spring is made of chrome silicon steel with a coating for corrosion resistance and lubricity. Some may prefer a bare stainless spring, in case that coating is compromised. No right answer here.
The green spring is also stiffer than a milspec rifle spring. On the upside, this delays unlocking the bolt and makes extraction easier. On the downside, a stronger spring increases carrier velocity and thus cyclic rate. This means the magazine has less time to present the next round for chambering. A higher cyclic rate is why heavier buffers (A5H3/4) are better with the green, since they slow the rate and counteract the effect of the spring. But then the gas drive, etc. should be adjusted for a heavier buffer.
Chrome silicon springs tend to be more consistent in cyclic rate and the Sprinco is proven to have a very long lifespan. You'll probably never have to replace it, though periodic inspection for surface defects is a good idea. A quality milspec spring (Colt, BCM, Vltor) is noticeably more consistent than a cheap one, but the spring will have to be replaced when it shortens over time.
Hopefully this helps you make an informed decision. The A5 is forgiving enough to handle less-than-optimal configurations, so you could try different things and still see an improvement from it.
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What are you trying to fix or accomplish with a different spring and buffer?
I can tell you from running an A5 off and on since 2011 that it's not going to do much of anything on a 16" mid other than make recoil feel clunky and slow. It makes an overgassed gun kick harder.
The A5, or any other buffer/spring combo, isn't going to fix over gassing. If the AR feels slow, try a lighter buffer.
If people subjectively prefer the Sprinco green for whatever reason, that's fine. Rock on. I think that some might not understand the difference it makes in the buffer system and how it has both pros and cons.
The Sprinco green spring is made of chrome silicon steel with a coating for corrosion resistance and lubricity. Some may prefer a bare stainless spring, in case that coating is compromised. No right answer here.
The green spring is also stiffer than a milspec rifle spring. On the upside, this delays unlocking the bolt and makes extraction easier. On the downside, a stronger spring increases carrier velocity and thus cyclic rate. This means the magazine has less time to present the next round for chambering. A higher cyclic rate is why heavier buffers (A5H3/4) are better with the green, since they slow the rate and counteract the effect of the spring. But then the gas drive, etc. should be adjusted for a heavier buffer.
Chrome silicon springs tend to be more consistent in cyclic rate and the Sprinco is proven to have a very long lifespan. You'll probably never have to replace it, though periodic inspection for surface defects is a good idea. A quality milspec spring (Colt, BCM, Vltor) is noticeably more consistent than a cheap one, but the spring will have to be replaced when it shortens over time.
Hopefully this helps you make an informed decision. The A5 is forgiving enough to handle less-than-optimal configurations, so you could try different things and still see an improvement from it.
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But, if the stiffer spring delays opening, wouldn't that slow down the cyclic rate?
Yes, my preference for the green spring is subjective. Recoil feels smoother and the ejection pattern is consistent.
Drill a hole about 3/16” deep in a tungsten weight. :D
Drilling tungsten isn't as easy as you think.
But, if the stiffer spring delays opening, wouldn't that slow down the cyclic rate? It does, but the overall effect seems to be an increase in cyclic rate. The additional force at maximum compression means greater acceleration of the reciprocating mass. See this comparisons of carbine springs with a Sprinco blue (the principle is the same):
http://www.vuurwapenblog.com/reviews/tests/ar-15-carbine-action-spring-performance-differences/
It's important to use a quality milspec spring, since cheaper ones may lead to erratic cyclic rates.
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That was a Sprinco blue spring. It is shorter than the green and there's nothing to indicate the compression and relaxation rate are the same.
But, if the stiffer spring delays opening, wouldn't that slow down the cyclic rate?
Not really. Whatever it does to delay the initial movement of the bolt will be countered by increasing the bolt velocity going into battery.
Springs are incredibly efficient, and will give you back almost all the energy you put into them. Most self loading guns rely on the impact of the bolt/slide to the rear to dissipate some of bolt energy as heat (compression of the elastomer tip of the AR buffer when it impacts), and then the spring returns the bolt to battery. When you use a stronger spring than designed, you've stored some of that impact energy instead of letting it go into the frame, and then you put it back into the forward movement of the bolt. The stronger spring essentially causes the bolt to "short stroke" instead of bottoming out with the full designed force.
Whatever kind of self loading mechanism you have, the best way of moderating the energy fed into the bolt/slide is by adding mass - like how a .40 USP has a heavier slide than a 9mm USP. In the case of a gas powered rifle, you also can control the energy directly by limiting the gas. Springs in either case just shift the energy around - it doesn't go away.
If I couldn't affect the gas or bolt/buffer mass, I would want to use a softer/thicker elastomer to dissipate more energy at the rear of bolt travel and a standard spring to keep forward velocities in check.
The other thing you can do with hammer fired weapons is to use a different leverage relationship between the hammer and bolt, since that only affects the first bit of bolt movement and not the rest of the cycle. Stiffer mainsprings or a squared firing pin stop in 1911s accomplishes this.
Drilling tungsten isn't as easy as you think.
Interesting, I drilled a tungsten weight just last week.....cutting fluid, patience and a cobalt bit.
Easy peasy.
Not really. Whatever it does to delay the initial movement of the bolt will be countered by increasing the bolt velocity going into battery.
Springs are incredibly efficient, and will give you back almost all the energy you put into them. Most self loading guns rely on the impact of the bolt/slide to the rear to dissipate some of bolt energy as heat (compression of the elastomer tip of the AR buffer when it impacts), and then the spring returns the bolt to battery. When you use a stronger spring than designed, you've stored some of that impact energy instead of letting it go into the frame, and then you put it back into the forward movement of the bolt. The stronger spring essentially causes the bolt to "short stroke" instead of bottoming out with the full designed force.
Whatever kind of self loading mechanism you have, the best way of moderating the energy fed into the bolt/slide is by adding mass - like how a .40 USP has a heavier slide than a 9mm USP. In the case of a gas powered rifle, you also can control the energy directly by limiting the gas. Springs in either case just shift the energy around - it doesn't go away.
If I couldn't affect the gas or bolt/buffer mass, I would want to use a softer/thicker elastomer to dissipate more energy at the rear of bolt travel and a standard spring to keep forward velocities in check.
The other thing you can do with hammer fired weapons is to use a different leverage relationship between the hammer and bolt, since that only affects the first bit of bolt movement and not the rest of the cycle. Stiffer mainsprings or a squared firing pin stop in 1911s accomplishes this.
My point was, if you delay the opening and speed up the closing, it's a wash :)
My point was, if you delay the opening and speed up the closing, it's a wash :)
It's a wash if your only concern opening speed and not feed jams.
However, a spring in its most extended position (bolt in battery) is going to have the least ability to affect bolt opening speed compared to a weaker spring. The biggest effect will be at full compression, not where you want it.
It's a wash if your only concern opening speed and not feed jams.
However, a spring in its most extended position (bolt in battery) is going to have the least ability to affect bolt opening speed compared to a weaker spring. The biggest effect will be at full compression, not where you want it.
Do you know how fast a carrier has to run before it will outrun a modern AR mag? Pretty damn fast! I had a grossly over-gassed shorty with stupid high carrier speeds. It never outran any of my magpul mags or modern GI mags. It never had a feed jam, even when I used it with a full auto lower.
In any case, when used with an A5 RE, the green spring gives my ARs smoother operation than a standard rifle spring does.
If you go back, you'll see I was questioning the claim that a stronger springs delays opening, speeds closing while giving higher carrier speeds. Seems to me there is a contradiction in there, someplace
Do you know how fast a carrier has to run before it will outrun a modern AR mag? Pretty damn fast! I had a grossly over-gassed shorty with stupid high carrier speeds. It never outran any of my magpul mags or modern GI mags. It never had a feed jam, even when I used it with a full auto lower.
In any case, when used with an A5 RE, the green spring gives my ARs smoother operation than a standard rifle spring does.
If you go back, you'll see I was questioning the claim that a stronger springs delays opening, speeds closing while giving higher carrier speeds. Seems to me there is a contradiction in there, someplace
Unless you combine overgassing with a stronger spring, there is no reason the bolt closing speeds are going to be anywhere as high as the opening. The opening velocity is absorbed by the impact of the buffer on the back of the buffer tube. So there isn't a good reason for a standard spring to close the action much faster than a correctly gassed action.
Imagine a spring that is twice as strong as required. It will resist BCG movement twice as hard and will cause it to rapidly short stroke, opening and closing at the same rate because it never dumps any energy into the buffer tube.
If you go back, you'll see I was questioning the claim that a stronger springs delays opening, speeds closing while giving higher carrier speeds. Seems to me there is a contradiction in there, someplace
I'm not the only one who thinks this is the case. Read this thread:
https://www.m4carbine.net/showthread.php?181201-Do-extra-power-buffer-springs-increase-or-decrease-cyclic-rate
The stiffer the spring the higher the cyclic rate.
The force returning the bolt to the forward position is stronger, so the acceleration is higher.
How fast the bolt slows down on the backward trip is largely unchanged due to the extreme force used to accelerate it.
The piston force is on the order of 1500 to 2000 pounds, so 2 or 3 lb/ins increase in spring rate is not going to change the time taken to get the carrier to the back of the extension by any appreciable amount, but, once the buffer bottoms out in the rear of the extension the velocity is zero, so all forward acceleration comes from the spring. Stiffer spring more force; more force, higher acceleration; higher acceleration, less time....
Realistically, the ideal spring is one that closes whatever mass bolt at an appropriate velocity for feeding. That's really its only job. The velocity the bolt opens with is controlled by gas and mass. Stoner designed a BCG, spring, gas tube and buffer that works for a 20" barrel and fixed stock. Colt created the short buffer tube and carbine gas system as a crude adaptation of the full size gun. It is not engineered to the same standard.
If Stoner had been tasked to create a 5.56mm carbine with a 14.5" barrel, it would likely have featured a much longer travel cam way for later bolt unlock, which would have resulted in 20" barrel cyclic rates. But shortening the gas tube and lightening the buffer is never going to result in a weapon that functions as well as the full size - no matter how much you screw around with the gas hole diameter.
Opening velocities are always higher than closing velocities.
Springs have friction losses, so some of the energy is lost.
The buffer impact does return quite a bit of energy.
You can see from this graph, the rebound velocity is about 58% of impact velocity.
https://dqzrr9k4bjpzk.cloudfront.net/images/812059/958061917.jpg
Unless you combine overgassing with a stronger spring, there is no reason the bolt closing speeds are going to be anywhere as high as the opening. The opening velocity is absorbed by the impact of the buffer on the back of the buffer tube. So there isn't a good reason for a standard spring to close the action much faster than a correctly gassed action.
Opening velocities are always higher than closing velocities.
Springs have friction losses, so some of the energy is lost.
The buffer impact does return quite a bit of energy.
You can see from this graph, the rebound velocity is about 58% of impact velocity.
https://dqzrr9k4bjpzk.cloudfront.net/images/812059/958061917.jpg
And I think it would be much more lopsided with an overgassed gun.
Interesting, I drilled a tungsten weight just last week.....cutting fluid, patience and a cobalt bit.
Easy peasy.
Whoose bit did you use? What fluid? What RPM? Maybe my lathe isn't stiff enough.
Whoose bit did you use? What fluid? What RPM? Maybe my lathe isn't stiff enough.
I think CO2 laser should do the job [emoji23]
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Whoose bit did you use? What fluid? What RPM? Maybe my lathe isn't stiff enough.
Dormer center bit, Viper venom cutting fluid, 550 rpm on a drill press. It did dull the bit to an extent.
The tungsten weights were from KAK
Carbide cuts tungsten like butter. I do it all the time, just have to have the right tooling.
Correct......didn’t have the size I needed to drill the spring pocket
Today I received the VLTOR A5 kit and added to the BCM receiver extension for a total of $90 shipped. When cycling the action with the charging handle I can definitely feel a difference, it’s very smooth! Will hopefully get to shoot it in a week or so. I have steel weights from my H buffer that I can use to lighten the A5H2 buffer if needed. Do you guys think I should shoot it first with A5H2 or lighten it up before the first go-round?
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Today I received the VLTOR A5 kit and added to the BCM receiver extension for a total of $90 shipped. When cycling the action with the charging handle I can definitely feel a difference, it’s very smooth! Will hopefully get to shoot it in a week or so. I have steel weights from my H buffer that I can use to lighten the A5H2 buffer if needed. Do you guys think I should shoot it first with A5H2 or lighten it up before the first go-round?
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I'd do the A5-2 first.
I would start with the H2 as well. The Odin barrel is gassed properly and will shoot very well with good ammo
Sparky5019
12-24-18, 12:52
I really like the A5H3 with a Sprinco green on my BCM BFH 11.5. This gun runs 99% suppressed so it does have an SLR AGB on it. Nice and smooth and ejects 3:30-4:00. I did test all the buffers with a BCM GB but I’ve been spoiled with the SLR AGB on previous guns so...
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