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Thread: Heavier spring or heavier buffer: which is better?

  1. #51
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    Quote Originally Posted by rsilvers View Post
    I have not seen a Colt M4 spring drawing, but it is unlikely they downgraded the material used for the M16 spring.

  2. #52
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    The ultimate spring, for this application, would be a mil spec spring that has been upgraded by being shot peened and electro polished. I don't feel that is necessary but if I were trying to create a $20 spring that is what I would do.

    17-7 wire costs 2.75x as much as chrome silicon valve spring wire so no one picked it to save money.

  3. #53
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    Quote Originally Posted by rsilvers View Post
    I know, but I was asking about your saying that stainless does not make a good spring material. I just wanted to be sure you knew that USGI springs were specifically 17-7 precipitation hardened stainless in condition H900.

    Are you saying that 17-7 PH spring temper H900 is not a good spring material?

    The 17-7PH H900 USGI spring will typically last for several barrels - even 100,000 rounds or more. As far as I am concerned, the inspection of it is just to check for a defective spring. You can check it on a scale and it may last for a few barrels. If yours lasted 2000 or 3000 rounds, it was almost certainly not a USGI spring. Also there is no harm in leaving the action locked back in storage.
    ==============================

    100K+ or several barrels...that's pretty impressive. I've never seen anyone recommend going that long before changing a buffer spring. I've read more than once they should be changed at 8k-10k rounds.

    SS does not make a better spring than CS. If, in fact SS is Mil-spec, it must be for other reasons: corrosion, wearing inside RE, galvanic reaction, etc.. But, IMO, I can't imagine the best spring lasting 100K.

    But maybe it's just me...

    .

  4. #54
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    Yes, music wire is better springiness than 17-7 PH. Mil spec was probably picked for corrosion resistance.

    I did not recommend changing the spring at 100k or after several barrels. I said it may last that long. I change them when they no longer meet the force specifications for a new spring.

    It is easier to tell people to replace them every 5, 8, or 10K rounds than explain how to test them for remaining life. A good analogy is telling people to change their engine oil every 3K miles rather than have them sample and test the oil.

  5. #55
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    skimming through, i didn't see this mentioned... in my opinion and experience, XP springs are good for troubleshooting problem guns. i have an extremely over-gassed gun (due to an un-requested port modification at a shop ) that runs too hot with an H2 and standard spring with NATO ammo, too slow with an H3 and standard spring with SAAMI ammo, but runs just right with all ammo with an H2 and XP spring.

    for example.

    don't put XP spring in guns that function fine. same for "enhanced" bolts and carriers, and some other things.

  6. #56
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    Quote Originally Posted by BufordTJustice
    Gentlemen (Markm, Gotm4),

    With all due respect, I must differ with you on this issue.

    Ten years ago, if we all started to talk about tinkering with buffer weights (how many times did I hear, "Who the hell needs an H buffer?!?!"), we would have been swiftly voted off the island. Recommending the use of H2 and H3 buffers would have gained us much ridicule.

    I have several friends who run their own regional short track racing team (mostly using ~350ci smallblocks w/ 4-barrel Holley carbs). They build their own engines...and wreck their own cars. A LOT of progress has been made in spring construction in the last 40 years. Even these rednecks (technically, I would fall into this social strata as well) have seen fit to upgrade their valve springs to chrome silicon springs. They now only have to replace the valve springs every other rebuild (and not because they have to). Before, they had serious problems with valve float at the engines' at redline (most tracks they RL at about 7100-7300 rpm). They were running 'uprated' conventional steel springs but still had to replace them about every race or else they would risk watching a connecting rod take a stroll down the backstraight. Since upgrading, valve float has been a non issue and spring life has increased exponentially. Do they know why this is? Nope. They are rednecks....but they'll cut off their members with a rusty butter knife before they switch back to the old valve springs.

    As for using up-rated springs in the AR (or ANY semi auto rifle), I think there may be merit. I have had VERY good luck tinkering in this area with benefits in smoothness and no detriment to reliability. Just as the H2 or H3 buffer may hurt reliability in someone's rifle as much as it may help another's, so too may a spring of different specification.

    I'm not saying who's right or wrong...I'm saying we don't know yet.....and there is so much to learn about how spring strength and buffer weight interact in the AR system. With new bolt carrier coatings further throwing a wrench into the mix by changing the internal friction of the system (In a linear or non-linear fashion, only God knows). I think that our effort in this area is to reduce the force that the BCG and buffer impart on the rear of the RE? In my mind, it seems this is simply the age-old discussion of heavy-slow or light-fast.

    I guess my only request is this: can we agree to disagree that there is benefit to tinkering with springs?

    I have had great results with using heavier CS springs....just the same it may DESTROY the reliability of another's perfectly running rig. I know that both of you have seen detrimental effects from using non-spec, aftermarket springs and I believe every word of the horror stories you've told.

    I'm an LEO and have zero background in the science or math in this area of study. I'm not an engineer. I am not an armorer. I'm just an average guy who is curious.

    Please don't take this as a challenge, Markm and Gotm4, as my knowledge is inferior to yours. I'm just trying to learn as much as possible about the system.
    I also agree that spring modifications have potential merit. If we look at how the AR system operates from an engineering point of view, the buffer spring is partly responsible for slowing down the BCG as it comes back, but perhaps more importantly, it is also responsible for sending the BCG forward and ensuring that the bolt is in battery. Weak buffer springs will not only be less likely to lock the bolt into battery (particularly if sand or other particles are creating more friction than normal), but will also increase the cyclic rate of the BCG. Couple this with a weak magazine spring and some hot ammo (and if you really want to mess things up, an oversized gas port as may be common from lower-tier commercial AR manufacturers), and you have the potential for the bolt closing on an empty chamber because the magazine spring cannot push the round up fast enough to deal with the increased cyclic rate of the BCG.

    In the AR system, timing is very important for reliable function and durability, particularly at the extreme edges of operation. What heavier buffers are supposed to do is slow down the BCG’s movement to the rear to bring guns running more gas (or gas at higher pressures) in line with the appropriate timings for bolt unlocking and soforth. Another reported advantage is increased parts life and reduced recoil, since the BCG moving more slowly to the rear will move more slowly forward (thus reducing the impact forces of the bolt slamming into battery), although admittedly, testing the lifespan of parts can be very difficult.

    Now where do I see a spring playing into all of this? Really, I would expect a heavier spring to be a valid substitute for a heavier buffer if done correctly. If done correctly, this will slow down the BCG appropriately as an H buffer would, but unlike just simply putting a heavier buffer in, a heavier spring would also increase the likelihood of the bolt going into battery under conditions where it might not (dry gun, excessive sand, etc). Thus, in theory, using a different spring in the end will result in a more reliable gun as compared to using a heavier buffer.


    However, in practice, this is pretty difficult to achieve. A stronger spring can, like anything else, create potential problems. Short-stroking would result if the spring is too strong. Reliability and durability could be affected by springs that aren’t properly treated or have poor QC. Each gas system and barrel length (therefore different pressures and dwell times) would require different spring setups, and running suppressed would affect reliability and durability as well. Spring wear over time would result in changes in the forces involved during rearward and forward movement of the BCG. Bolt bounce, particularly on FA guns (especially SBR’s), could be exacerbated because of the increased velocity of the BCG on its forward return due to a stronger spring. The gun may also be reliable with higher-pressure ammo, but weaker ammo may not be strong enough to overcome the increased resistance caused by a strong buffer spring (and of course, this would change over time as the spring wears out and becomes weaker). Then we have to remember that just because a gun works now doesn’t mean it’s running optimally, and if it’s not, it may work in most cases, but may fail in extreme cases where an optimized gun (in pressure, dwell time, unlock timing, etc) will continue to function.

    It’s akin to saying that Bushmasters and Rock River’s are great AR’s. I mean they work for most people right? But why do we consider them lower tier manufacturers even though these guns will work for most people? Because we understand that the engineering and manufacturing processes used in higher tier guns are important for the reliability and durability of the AR platform in relatively extreme cases for most civilian shooters. Most shooters don’t send thousands of rounds downrange every year and don’t depend on their rifles on a daily basis. Thus, many won’t experience problems with their guns for a long time. But even though these guns may work for most people, we understand that they are not on the same level as other manufacturers. The same applies here. Just because your gun may work with a certain setup doesn’t mean it’s running optimally, and just because it works now doesn’t mean it’ll work later at a point where a properly set up AR should be running.


    While I think changing springs can theoretically increase the reliability of the AR platform, in practice, with all of the different setups (barrel length, gas system, suppressors, etc) available, it’s just not worth the trouble at this point. Without consistent QC from a spring manufacturer, multiple springs that will be optimal for the multitude of different AR setups available, and the engineering reviewed to ensure proper timing with different spring setups, it’s, in most cases, not worth it to deal with aftermarket springs. Yes, it can work, but it’s much tougher than switching buffers out and requires a lot more finesse. I run a standard spring with an H buffer in my BCM midlength for that very reason, and will generally only suggest buffer changes to deal with timing issues. Different springs can work, and while they can offer more advantages than switching a buffer out, it’s also much easier to screw up. YMMV.
    Last edited by TwitchALot; 10-02-10 at 17:01.

  7. #57
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    While it's true the heavier buffer will slow down the speed of the reciprocating mass, it's also true it now has more mass. More mass means more kinetic energy. It's likely the slower but more massive reciprocating mass is just as stressful on part life.

    Heavier BCGs don't reduce recoil. The only thing it can do increase the duration of the recoil impulse and reduce it's peak- softening a sharp jab to a longer push. Free recoil energy will be the same but felt recoil will be different
    Last edited by MistWolf; 10-02-10 at 22:57.

  8. #58
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    Quote Originally Posted by MistWolf View Post
    While it's true the heavier buffer will slow down the speed of the reciprocating mass, it's also true it now has more mass. More mass means more kinetic energy. It's likely the slower but more massive reciprocating mass is just as stressful on part life.

    Heavier BCGs don't reduce recoil. The only thing it can do increase the duration of the recoil impulse and reduce it's peak- softening a sharp jab to a longer push. Free recoil energy will be the same but felt recoil will be different
    the idea behind slowing the action is to allow chamber pressure to diminish, allowing easier extraction. less wear on the bolt and extractor, and less headspace wear via barrel extension and bolt lugs.

  9. #59
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    Quote Originally Posted by bkb0000 View Post
    the idea behind slowing the action is to allow chamber pressure to diminish, allowing easier extraction. less wear on the bolt and extractor, and less headspace wear via barrel extension and bolt lugs.
    DOH! That part kinda slipped my mind. I was thinking more along the lines of simple battering self loaders endure. Thanks for the reminder

  10. #60
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    Quote Originally Posted by rsilvers View Post
    I am extremely enthusiastic about improved springs - I am just not into false claims of improvement. When I see cryogenic treatment listed my BS detector is on extreme alert right up there with those magnetic energy bracelets on late night TV.

    As for a heavier buffer - sure, if the normal buffer is too light. I guess what I don't know is why you think your normal buffer is too light.
    HAAA....HAAAAA....

    I'm surprised how many people I see with those bracelets. If they work so well, then imagine what should happen when your whole body gets exposed to a 1.5 Tesla MRI magnet(or whatever strength they are now).

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