View Full Version : Concerning Rifle-Length Buffer Systems
Vapor Trail
05-12-12, 20:53
From what I understand, the AR has less felt recoil than other platforms because the stock is in line with the shoulder, the buffer assembly is horizontal and continues into the buttstock, etc. I've seen pictures with people utilizing a longer-than-usual buffer assembly, and to my understanding this is known as a rifle-length buffer system. The last person I saw using one was Cody Leeper, shooting the "late" NGA X7, competing in 3-Gun.
Do rifle-length buffer systems have less muzzle rise/felt recoil? I understand the downside, how you aren't able to adjust your length of pull, but is it worth it? Does a longer barrel also reduce recoil?
Search for threads on the VLTOR A5 buffer system
Vapor trail. How old are you? Just curious because some of your posts are so elementary I don't get it. Apparently you do some research or at least reading. Why don't you actually go and shoot an m16 rifle and discover some of these things on your own.
Nightvisionary
05-13-12, 04:38
A longer barrel will have more recoil.
Longer barrel = more velocity, and as you know every action has an equal and opposite reaction. More energy means a greater "reaction"
Although a longer barreled AR will normally use a rifle length gas system and have less felt recoil than a shorter barreled M4 because of the gas pressure affecting bolt carrier and buffer speed.
I may be incorrect but I don't believe recoil works that way. A rifle with a longer barrel may produce slightly more velocity however with the increase in barrel length comes an increase in mass. More mass= less recoil.
Also secondary recoil effects of hot gas momentum increase as barrel length decreases.
dwhitehorne
05-13-12, 06:37
I don't know about the whole muzzle velocity increased recoil thing. From experience I can tell you any stock 20 inch barrel A1 or A2 I have fired had less felt recoil that any stock carbine I have shot. Especially in full auto. We use to have M16A1 patrol rifles that were auto. Most of the carbines at work are now semi auto. Occasionally I will pull a fixed stock auto lower and put it on one of the new carbines and you can definately feel the difference. Those A5 stocks sure look to be a good combination. David
Robb Jensen
05-13-12, 06:48
Rifle/carbine weight, gas system length, gas port size, bullet weight, bolt carrier weight, muzzle devices, buffer weight and buffer spring rate effect felt recoil.
Rifle buffer springs are longer and lower spring rates vs CAR length buffers but rifle buffers are 5.4oz vs CAR length buffers which are 3.0oz-5.6oz depending on which you have. Rifle length buffered guns generally cyclic slower and are more controllable as well.
so did you buy your 7.62x51sbrHK45.375cheytac.338LapuaPDWFullMetal AR15 yet? :meeting:
There's actually two separate subjects we're discussing here- Recoil, and * Perceived* Recoil.
There's no changing recoil. A rifle delivering a 62 grain projectile at 3100 feet per second is going to recoil with 1300 ft lbs, not matter what sort of rifle it is. Newton Rules that "all actions have an equal and opposite reaction". ( the actual reactive force is higher than that, but we'll get to that in a minute)
However, the weight of the Rifle will 'Absorb' a proportional amount of that energy ( because "an Object at rest will remain at rest").
"Perceived" or 'Felt" Recoil is really complex. In the Case of the AR15 pattern Rifle, the axis of the recoil is in-line with the stock, which is were the rifle is braced, normally, so there is actually a bit MORE actual recoil, as less of the force is not re-directed into rotational movement (i.e. 'Muzzle Rise'). It does feel like less recoil however, as it is more even, directional, and controlled.
Because the AR is (compared to most rifles) light weight, the mass of the reciprocating elements (BCG, Buffer, Etc.,) stretches out the recoil impulse (making it longer in time), which feels like less recoil.
A heavier buffer will move slower (as in a carbine) and if it can move a longer distance( as in a Rifle length), it also feels lighter. Though it may be perceived as lighter, it never is- the third law, "every action has an equal and opposite reaction" never lets it just 'go away'.
A funny part is that a great deal of the actual recoil comes from not the bullet leaving the barrel, but the gases that are jetting out with it.
A Muzzle Brake, or Compensator directs a potion of these gasses to the side (and usually up and slightly back) so it does actually reduce a potion of the actual recoil. In addition, since a small portion of gasses are redirected aft in the DI system, a small amount of recoil is redirected even without a muzzle device.
Because the gasses escaping a longer barrel are moving slower (even though the projectile is moving faster) the differences in barrel length pretty much even out when you discount the additional weight of the longer barrel.
To your original question, what you referred to as longer receiver extensions are actually the correct ones, as designed by Sargent Stoner way back once upon a time. The 'Carbine' Length Stocks are an modification of the original design, and are less forgiving, as they are trying to do the same amount of work in less space.
Really, IMO, adjusting your LOP is a minor consideration. While it's nice to have a shorter stock in some situations, it tends to get over emphasized.
There's actually two separate subjects we're discussing here- Recoil, and * Perceived* Recoil.
There's no changing recoil. A rifle delivering a 62 grain projectile at 3100 feet per second is going to recoil with 1300 ft lbs, not matter what sort of rifle it is. Newton Rules that "all actions have an equal and opposite reaction". ( the actual reactive force is higher than that, but we'll get to that in a minute)
However, the weight of the Rifle will 'Absorb' a proportional amount of that energy ( because "an Object at rest will remain at rest").
"Perceived" or 'Felt" Recoil is really complex. In the Case of the AR15 pattern Rifle, the axis of the recoil is in-line with the stock, which is were the rifle is braced, normally, so there is actually a bit MORE actual recoil, as less of the force is not re-directed into rotational movement (i.e. 'Muzzle Rise'). It does feel like less recoil however, as it is more even, directional, and controlled.
Because the AR is (compared to most rifles) light weight, the mass of the reciprocating elements (BCG, Buffer, Etc.,) stretches out the recoil impulse (making it longer in time), which feels like less recoil.
A heavier buffer will move slower (as in a carbine) and if it can move a longer distance( as in a Rifle length), it also feels lighter. Though it may be perceived as lighter, it never is- the third law, "every action has an equal and opposite reaction" never lets it just 'go away'.
A funny part is that a great deal of the actual recoil comes from not the bullet leaving the barrel, but the gases that are jetting out with it.
A Muzzle Brake, or Compensator directs a potion of these gasses to the side (and usually up and slightly back) so it does actually reduce a potion of the actual recoil. In addition, since a small portion of gasses are redirected aft in the DI system, a small amount of recoil is redirected even without a muzzle device.
Because the gasses escaping a longer barrel are moving slower (even though the projectile is moving faster) the differences in barrel length pretty much even out when you discount the additional weight of the longer barrel.
To your original question, what you referred to as longer receiver extensions are actually the correct ones, as designed by Sargent Stoner way back once upon a time. The 'Carbine' Length Stocks are an modification of the original design, and are less forgiving, as they are trying to do the same amount of work in less space.
Really, IMO, adjusting your LOP is a minor consideration. While it's nice to have a shorter stock in some situations, it tends to get over emphasized.
and thats a wrap.
Very good explanation, but a couple of corrections are needed
"Perceived" or 'Felt" Recoil is really complex. In the Case of the AR15 pattern Rifle, the axis of the recoil is in-line with the stock, which is were the rifle is braced, normally, so there is actually a bit MORE actual recoil, as less of the force is not re-directed into rotational movement (i.e. 'Muzzle Rise'). It does feel like less recoil however, as it is more even, directional, and controlled.
The inline design of the AR doesn't increase recoil. As pointed out, recoil energy generated will be the same
A heavier buffer will move slower (as in a carbine) and if it can move a longer distance( as in a Rifle length), it also feels lighter.
The distance traveled by the BCG and buffer is the same in both the rifle and the carbine
Because the gasses escaping a longer barrel are moving slower (even though the projectile is moving faster) the differences in barrel length pretty much even out when you discount the additional weight of the longer barrel.
The actual velocity of the ejecta (the gases) is never faster than the bullet until the bullet uncorks the barrel. Once it does the gases are faster than the bullet. Once uncorked, the gases have the same velocity regardless of barrel length. For the purposes of figuring out free recoil of small arms, the velocity of the gases is (if I recall correctly) about 4750 fps
A funny part is that a great deal of the actual recoil comes from not the bullet leaving the barrel, but the gases that are jetting out with it.
This is spot on. During my own research, I was amazed to discover that the ejecta accounts for roughly 1/3 to 1/2 of the free recoil, depending on the load.
While it does not show the formula used to in the calculations, here is link to a Recoil Calculator (http://www.handloads.com/calc/recoil.asp)
There's actually two separate subjects we're discussing here- Recoil, and * Perceived* Recoil.
There's no changing recoil. A rifle delivering a 62 grain projectile at 3100 feet per second is going to recoil with 1300 ft lbs, not matter what sort of rifle it is. Newton Rules that "all actions have an equal and opposite reaction". ( the actual reactive force is higher than that, but we'll get to that in a minute)
However, the weight of the Rifle will 'Absorb' a proportional amount of that energy ( because "an Object at rest will remain at rest").
"Perceived" or 'Felt" Recoil is really complex. In the Case of the AR15 pattern Rifle, the axis of the recoil is in-line with the stock, which is were the rifle is braced, normally, so there is actually a bit MORE actual recoil, as less of the force is not re-directed into rotational movement (i.e. 'Muzzle Rise'). It does feel like less recoil however, as it is more even, directional, and controlled.
Because the AR is (compared to most rifles) light weight, the mass of the reciprocating elements (BCG, Buffer, Etc.,) stretches out the recoil impulse (making it longer in time), which feels like less recoil.
Thanks, thats what i was trying to get at.
MistWolf, thats intersting. I would have never guessed that the gas would account for that much of the recoil, but I supposse thats why comps work so well.
Very good explanation, but a couple of corrections are needed
Thanks- I am but a Humble Sea Captain, and though counting myself a Rifleman lo, these past 30 years, I should have noted in my remarks that this was my understanding of the elements, and that I am not an SME, nor a scientist- not even a physics teacher.
I stand corrected, and thank you for the effort.
The inline design of the AR doesn't increase recoil. As pointed out, recoil energy generated will be the same
Absolutely. I was referring to the fact that the rotation (muzzle climb) of a non-inline design would redirect some of the recoil energy upwards, instead of transferring it to the shooter's shoulder. I suppose that's the difference between 'felt' and 'perceived' recoil.
The distance traveled by the BCG and buffer is the same in both the rifle and the carbine
DOH! I shoulda known that.
The actual velocity of the ejecta (the gases) is never faster than the bullet until the bullet uncorks the barrel. Once it does the gases are faster than the bullet. Once uncorked, the gases have the same velocity regardless of barrel length. For the purposes of figuring out free recoil of small arms, the velocity of the gases is (if I recall correctly) about 4750 fps
See, I thought that the long barrel meant less pressure when the round clears the muzzle, which would translate into less velocity. More 'Lies my father told me'! :p
(actually, it was likely my uncle, another notorious liar-to-children)
(a bit of a family tradition)
This is spot on. During my own research, I was amazed to discover that the ejecta accounts for roughly 1/3 to 1/2 of the free recoil, depending on the load.
I once decided to remove the brake from my Mod12BVSS in .308 mid-range day, to see if it effected POI. I couldn't believe the difference it made in recoil. (It didn't seem to make any difference in the POI)
I can discern no noticible difference in the felt recoil of my 16" BCM middy with standard carbine recoil spring and H buffer and my father's 16" PSA middy with a standard A2 fixed stock assembly. Both wear standard A2 flash suppressors.
Either the difference is minimal enough to be insignificant or my recoil palate is not refined enough to note the difference.
sinlessorrow
05-13-12, 16:05
Search for threads on the VLTOR A5 buffer system
this, its like the Rifle system combined with the Carbine system into one bad ass setup thats more reliable than both:thank_you2:
There's no changing recoil. A rifle delivering a 62 grain projectile at 3100 feet per second is going to recoil with 1300 ft lbs, not matter what sort of rifle it is.
This is incorrect.
Total energy of the system includes the muzzle energy plus the recoil energy. Conservation of momentum, momentum of the firearm and the projectile equals zero, gives that the recoil energy will be significantly less due to the mass of the firearm in relationship to the projectile.
Using E = 1/2[mv(squared)] and p =mv,
Then E = p(squared)/ 2m to get the ratio
Ef / Ep = m(projectile) / m(firearm) to give
Ef = Ep [m(projectile) / m(firearm)]
Which means that the heavier the firearm, the less recoil energy. The recoil energy is dissipated thru the mass of the firearm as well as any damping forces employed by the firearm.
This is incorrect.
Total energy of the system includes the muzzle energy plus the recoil energy. Conservation of momentum, momentum of the firearm and the projectile equals zero, gives that the recoil energy will be significantly less due to the mass of the firearm in relationship to the projectile.
Using E = 1/2[mv(squared)] and p =mv,
Then E = p(squared)/ 2m to get the ratio
Ef / Ep = m(projectile) / m(firearm) to give
Ef = Ep [m(projectile) / m(firearm)]
Which means that the heavier the firearm, the less recoil energy. The recoil energy is dissipated thru the mass of the firearm as well as any damping forces employed by the firearm.
You are correct.
Just to be clear, a load launching a 62 gr bullet at 3100 fps using the same weight powder charge will generate the same energy regardless of the weight of the weapon.
Still, as you point out, the more mass the weapon has, the more energy needed to move it
skullworks
05-13-12, 18:33
Still, as you point out, the more mass the weapon has, the more energy needed to move it
So there you have it; the answer to your original question (which you should've been able to figure out without starting this thread): all other things being equal a rifle length buffer and/or longer barrel will equal more mass = less felt recoil.
Yes, but only because there will be an increase in the whole mass of the rifle, not because the buffer has more mass. The energy that moves the BCG and buffer to the rear is stored in the action spring which is then used to return everything to battery.
Even if the bolt is locked back, the buffer doesn't reduce free recoil because it has to be accelerated to the rear, then decelerated to a full stop. But all that monkey motion slows the acceleration from recoil and softens the blow. It's like the difference between using the brakes to bring a car to a full stop after accelerating to 75 mph, or or using a brick wall to get a quicker result
skullworks
05-14-12, 07:09
Sorry, I just realized I misquoted you as the being the OP in my previous comment. My apology for that: :suicide:
Yes, but only because there will be an increase in the whole mass of the rifle, not because the buffer has more mass.
Still; (all things being equal) the total mass of the of the rifle cannot remain unchanged if you add mass to it - be it the to the buffer or anywhere else, so your statement is rendered impossible by the laws of physics.
Also, if we look to the mechanics side of things a buffer with more mass takes more force to move, which means that more of the recoil energy will be sucked up in the process of moving the buffer to the rear. What kinda muddles the issue is that the buffer springs are different, which also affects the rear movement of the buffer. Anyway, the smoother the travel of the buffer (and BCG) the smoother/less felt recoil there will be.
I would have never guessed that the gas would account for that much of the recoil, but I supposse thats why comps work so well.
It's what got us to the moon! :-)
Robb Jensen
05-14-12, 07:38
My 3gun rifle is set up like this:
3.0oz CAR buffer
standard rate Brownells chrome silicone CAR buffer spring
Magpul PRS stock with a RRA 9mm delrin spacer
JP LMOS 6.25oz bolt carrier
BCM bolt
Melonited BCM SS410 18" rifle gas barrel
SJC Titan muzzle brake
It shoots nice and very flat with very little recoil. I'm still experimenting and am in the process of cutting down a RRA delrin spacer so I can use a VLTOR A5 3.8oz buffer (all four weights are steel) and a standard rate A2 buffer spring.
I'm still experimenting and am in the process of cutting down a RRA delrin spacer so I can use a VLTOR A5 3.8oz buffer (all four weights are steel) and a standard rate A2 buffer spring.
A "spacer" in the buffer tube?!? Horrors!!!!! ;) :D
this, its like the Rifle system combined with the Carbine system into one bad ass setup thats more reliable than both:thank_you2:
I run an A5 on my BCM middy and I love it! It just may be the perfect AR setup :D
Robb Jensen
05-14-12, 21:25
A "spacer" in the buffer tube?!? Horrors!!!!! ;) :D
¿Qué?
Don't use a spacer in a rifle length receiver extension when you're using CAR length buffer and spring and you'll have a destroyed charging handle and possibly fubar'd upper receiver.
sinlessorrow
05-14-12, 21:41
¿Qué?
Don't use a spacer in a rifle length receiver extension when you're using CAR length buffer and spring and you'll have a destroyed charging handle and possibly fubar'd upper receiver.
not to mention a destroyed carrier key and a screwed up lower as well
¿Qué?
Don't use a spacer in a rifle length receiver extension when you're using CAR length buffer and spring and you'll have a destroyed charging handle and possibly fubar'd upper receiver.
I was messin' with you, Robb. I recommended using an H3 buffer(same weight as the A2 rifle buffer), an A2 rifle spring, and a "SPACER", in an AR-10 buffer tube, to duplicate the performance of the A5 system. You'd have thought I suggested murder by the response I got. Funny thing is, my setup has been working just fine, for months now.
sinlessorrow
05-14-12, 23:44
I was messin' with you, Robb. I recommended using an H3 buffer(same weight as the A2 rifle buffer), an A2 rifle spring, and a "SPACER", in an AR-10 buffer tube, to duplicate the performance of the A5 system. You'd have thought I suggested murder by the response I got. Funny thing is, my setup has been working just fine, for months now.
that wont duplicate the performance of the A5 though.
the A5 buffer has 4 weights, the final one has a spring that helps keep the weights forward during unlocking.
it also uses the Rifle action spring that is a huge plus.
that wont duplicate the performance of the A5 though.
the A5 buffer has 4 weights, the final one has a spring that helps keep the weights forward during unlocking.
Agreed.
What is unclear to me is the effect of the weights being biased forward by the spring.
Does it help further reduce bounce during locking?
or
keep unlocking consistently delayed for more robust cycling?
Both?
that wont duplicate the performance of the A5 though.
the A5 buffer has 4 weights, the final one has a spring that helps keep the weights forward during unlocking.
it also uses the Rifle action spring that is a huge plus.
Sorry, but I can't agree. The only reason the A5 has 4 weights is probably to allow them to use standard size weights in an over-length buffer. Special sized weights only adds to the cost.
Nobody has confirmed the purpose of the spring, or if it really has much of an effect at all. Some people mentioned removing it and noting no difference. It may have more benefit under full-auto fire, but who knows. In firing both systems side by side, using the same upper and ammo, I couln't discern the difference and I doubt you could either.
You'll note that my modification also uses the A2 rifle spring.
I feel that the benefit of the buffer weight and the rifle spring would far outweigh any edge the small spring might provide.
Agreed.
What is unclear to me is the effect of the weights being biased forward.
Does it help further reduce bounce during locking?
Now, that is a possibility, in which case my thoughts on it being more beneficial under full-auto fire than semi-auto, makes even more sense.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.