View Full Version : Heavier spring or heavier buffer: which is better?
dorchester
09-25-10, 06:57
My BCM 14.5 carbine length upper functions with .223 pressure ammo either with a standard strength blue CS action spring and an H1 buffer OR with a Tubbs flat wire CS spring and a carbine weight buffer. I'm trying to determine if there is an inherent advantage to either combination. They both work with a wide range of ammo as far as my subjective testing goes, so which should I set as the standard configuration for this carbine? Without real instrumentation, I'm at the coin toss point. Unless someone can give me an insight to the two combinations I might be missing. Thanks.
Robb Jensen
09-25-10, 09:08
The BCM with a standard rate spring and a H buffer will run just fine. If you'll be shooting lots of 5.56mm NATO pressure ammo and/or suppressed a lot I'd recommend a H2 buffer for use with a CAR gas gun.
I don't see the need for extra power springs but then again I'm just weird.
dorchester
09-25-10, 09:34
Hey, I've learned a lot from your posts (mostly weird stuff, though). Seriously, I like the point that the Tubbs spring is supposed to act more like the longer rifle spring rather than that it is stronger than normal. I just don't know if it's true or even significant. This carbine will not be suppressed and I would like it to be tolerant of 75gr 5.56 through 55gr .223 loads. All this while being as soft shooting as possible while running the 75gr 5.56. I know, I don't want much.
LonghunterCO
09-25-10, 10:00
Could I ask the same question? On the buffer anyway, for a Midlength gas 16" upper (BCM of course:D).
BufordTJustice
09-25-10, 14:18
I have a buddy who just purchased a BCM 14.5" carbine (w/ A2x FH). He runs an H3 w/ Springco Blue std power buffer spring. However, he uses a well worn BCG (the bearing surfaces are pretty smooth) and he also uses a Fail Zero coated hammer (to further reduce friction). His gun runs great.
W/ a normal buffer spring, an H2 should be great for you if you run lots of milspec ammo, as GotM4 stated.
In my 16" BCM middy, I run a Fail Zero (Spike's version) BCG, and trigger group, FSC556, Red Springco XP CS buffer spring, and H3 buffer.
Gun runs like stink even after 200 rds of tula .223.
Unless you're running a coated BCG and hammer to reduce friction, an H2 and std power buffer spring would work well in a 16" middy.
The Tubbs, which I also have used in this setup...feels much more like the std buffer spring than it does the springco red spring. Both worked well for me.
Bottom line, every gun is different and if you're willing to tinker (i.e. buy thing you may never use), going with the heaviest buffer and spring setup that your gun will run (i.e. properly function and lock back on empty) seems to be beneficial. Mine runs amazing....but YMMV.
The_Hammer_Man
09-25-10, 17:31
I have a similar setup, 14.5" BCM w/FSC556, and it eats pretty much anything I give it as long as its reasonably close to MILSPEC.
I have two different spring/buffer setups,
One for light/less than milspec pressure loads,
Second for heavy bullet/high pressure loads like milspec 77grainers.
Normal/light= CS Blue Carbine Spring w/ H-buffer
Heavy= Tubbs w/either a normal buffer or one of the H's depending on bullet weight and pressure charge. Some will cycle with one but not the other.
As the previous poster stated.. tinker.
Sparky5019
09-25-10, 19:16
From my experience and knowledge of physics (admittedly limited); if I wanted to prolong the recoil impulse or keep the breech locked closed for a longer time, I would use an extra power spring (like a Tactical Springs Red) rather than add to the reciprocating mass in the action...but like Robb, I'm weird in my own way too!
Sparky
dorchester
09-25-10, 21:29
As a couple of posters have noted: tinker. Which I have, quite a lot, the carbine works well with either combo and with the wide range of cartridges I desire. It looks like there is no "book" answer to this one. Heads or tails, the lady or the tiger.
Those junky aftermarket springs have no place in any of my guns. Definitely dial the weapon in with the buffer, NOT the spring.
Those junky aftermarket springs have no place in any of my guns. Definitely dial the weapon in with the buffer, NOT the spring.
=========================
MarkM,
That's my understanding.
A quality AR maker's rep told me this past Wednesday, that the slower the BCG moves the better, (Which is still going to be pretty fast) and the Buffer controls the speed. He said a heavy spring has no place in a functioning gun, especially a factory "tuned" one.
He told me they got a gun back last month under warranty that the guy claimed wasn't reliable. Once the gun is in the shop, they see a heavier spring was installed. They call and confront the guy and he says, "It is a "better" spring than the one that was in the gun!" They asked him if the gun worked with the original spring and tells them, "Yes, it worked fine but this is a better spring!". Oh well...
I couldn't do that job. I'd have to say, "Well then go ahead and use the "better" spring but just get used to your gun failing...stupid!"
.
Robb Jensen
09-26-10, 12:19
=========================
MarkM,
That's my understanding.
A quality AR maker's rep told me this past Wednesday, that the slower the BCG moves the better, (Which is still going to be pretty fast) and the Buffer controls the speed. He said a heavy spring has no place in a functioning gun, especially a factory "tuned" one.
He told me they got a gun back last month under warranty that the guy claimed wasn't reliable. Once the gun is in the shop, they see a heavier spring was installed. They call and confront the guy and he says, "It is a "better" spring than the one that was in the gun!" They asked him if the gun worked with the original spring and tells them, "Yes, it worked fine but this is a better spring!". Oh well...
I couldn't do that job. I'd have to say, "Well then go ahead and use the "better" spring but just get used to your gun failing...stupid!"
.
Yep it's funny. Lots of people mention 'mil-spec' a lot for this or that but then use springs which have no known mil-spec......
Mil-spec buffer springs have a minimum and maximum length for rifle length and CAR length springs which is in the USMC technical manuals. I've yet to see where aftermarket extra power so-called better springs have such specs for length.
BufordTJustice
09-26-10, 17:37
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.
Robb Jensen
09-26-10, 17:46
Point taken.
I don't know if you read the article in SWAT magazine by Pat Rogers (titled Filthy 14) where he used a BCM midength to 31K rounds with standard CAR length buffer springs and a H buffer, the rifle was used by students in a training environment. Rifle was cleaned twice IIRC during this whole time, BCG changed out once when a bolt broke at 14K something rounds. The rifle shoots 2" at 50yds using an Aimpoint.
Would it have run better with an aftermarket spring? I don't know but 31K is pretty friggin' impressive.
BufordTJustice
09-26-10, 17:54
Point taken.
I don't know if you read the article in SWAT magazine by Pat Rogers (titled Filthy 14) where he used a BCM midength to 31K rounds with standard CAR length buffer springs and a H buffer, the rifle was used by students in a training environment. Rifle was cleaned twice IIRC during this whole time, BCG changed out once when a bolt broke at 14K something rounds. The rifle shoots 2" at 50yds using an Aimpoint.
Would it have run better with an aftermarket spring? I don't know but 31K is pretty friggin' impressive.
I heard about it here a while back...is it on the news stands? I would LOVE to read that. Results do speak for themselves....
EDIT: I'm looking on SWAT magazine's website through Sep-2010 and don't see an article of that title. Is it in the Oct-2010 issue? I'm gonna keep looking....
Thomas M-4
09-26-10, 19:37
No reason to run a stiffer buffer spring the engineers didn't pull that spring rate out of thin air. Now after saying that I do run a CS sprinco blue standard rate spring with an H-buffer. The CS will have longer life nothing more. The SS will not rust a good thing IMHO for a service rifle that may or may not get good PM.
This debate reminds me racing just because you FEEL a difference does not mean you have actually have an improvement dyno testing with your butt will not give you good result in the end.
Robb Jensen
09-26-10, 19:47
EDIT: I'm looking on SWAT magazine's website through Sep-2010 and don't see an article of that title. Is it in the Oct-2010 issue? I'm gonna keep looking....
I just read it about 2 weeks ago (borrowed the issue from a friend and gave it back).
BufordTJustice
09-26-10, 19:51
I just read it about 2 weeks ago (borrowed the issue from a friend and gave it back).
t26.
I don't see it through September, so I'll look for the Oct issue. Thank you for the heads-up, sir. :)
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.
CS springs are rated for higher temps than music wire, and so have a benefit in something as hot as a racing engine - that is what ASTM A877 is - valve spring wire. This is not the same application as the buffer spring in an AR, which never sees temps over 160 F (even if left in the dash of your military vehicle in the desert). There are premium carbon wires, such as Mt Joy Rocket Wire, which are better for gun springs than CS wire.
Flat-wire buffer springs are not better or even as good as a round-wire spring because the OD and ID is confined by the buffer and tube, so they are only flat due to missing material on the leading and trailing edge. This results in more stress. I predict earlier failure and possible spring breakage. The USGI spring is the correct and best spring for the AR buffer. Yes, they got it right 40+ years ago.
Same goes for extra-power extractor springs. HD extractor spring == sooner failure. This is very easy to prove with spring simulation software.
I heard about it here a while back...is it on the news stands? I would LOVE to read that. Results do speak for themselves....
EDIT: I'm looking on SWAT magazine's website through Sep-2010 and don't see an article of that title. Is it in the Oct-2010 issue? I'm gonna keep looking....
======================
It is the October issue.
.
BufordTJustice
09-26-10, 20:53
======================
It is the October issue.
.
Gotcha. Thank you.
No reason to run a stiffer buffer spring the engineers didn't pull that spring rate out of thin air...The spring rate is also tuned to a specific reciprocating mass.
Going to a heavier buffer increases the reciprocating mass and the original spring spec may no longer be the right one
Blankwaffe
09-26-10, 21:02
Gotcha. Thank you.
http://www.slip2000.com/articles.html
BufordTJustice
09-26-10, 21:04
http://www.slip2000.com/articles.html
DOUBLE thank you. :)
dorchester
09-27-10, 04:06
Wow, I'm a little surprised at the lack of enthusiasm for improved spring designs by many. However, the professionals here seem pretty firm in favor of the heavier buffer route. A clue. I'm going with the heavier buffer until an authoritative source can prove the advertising about flat wire springs to be true.
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.
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.
So, for the record, what is your take on Sprinco's springs?
http://sprinco.com/tactical.html
Rocket Wire (a high grade of music wire) is more than 20% higher minimum tensile strength than certified CS valve spring wire (0.022 wire diameter). So I would take a (properly designed) Rocket Wire spring over a chrome silicon spring any day for an extractor spring, where there is so little room that having an edge matters. But I am fine with mil-std stainless for buffer springs as they last almost forever anyway and so I will take the corrosion resistance.
"This computerized, ultra low temperature process (-320°F) increases the strength & wear life of the parent material."
Ok, take a length of wire and cut it into two pieces. Cryo one of them. Do a tensile strength test on each wire. Repeat 10 times and post the average results. Extraordinary claims require extraordinary evidence. If there is a strength gain which exceeds the measurement error of the test equipment, I will be proven incorrect.
when I tried to shoot a Noveske 12.5" barrel with an M4-2000 it would not function with a standard USGI buffer spring and H buffer. The bolt cycled so fast that it frequently outran several revisions of the PMAG. It is probably for this reason that the Switchblock was created.
Sprinco can make all the claims they want, but their red spring allowed my SBR to cycle semi-automatically suppressed, without frequent bolt over base malfunctions. Of course YMMV. I hope that Vltor's new A5 system makes many suppressed SBR problems go away.
FWIW, Mike Pannone is a strong proponent of Sprinco (and Noveske, BCM, etc). If you read his real-world tests, he generally uses Sprinco springs.
If your rifle is working too fast - in your case because of some combination of gas port size and sound suppressor, then you want to try to slow it down. I would first try H2/H3 buffer, and if that is not enough - a red Springco spring, or an HK-416 spring, would be the next thing to test.
Yes, that's why I went with a "red" Sprinco spring and 5.4 ounce DPMS buffer.
That said, unsuppressed, the gun will short stroke with that combination. As you guys know, SBRs with suppressors get tricky
Most likely there is a combination which will work suppressed and unsuppressed. What happens with a USGI spring and the DPMS buffer?
dorchester
09-27-10, 11:59
Mr Silvers, There really never was an "original" buffer on this gun. I substituted a BCM upper on a LWRC lower which originally had their piston upper on it. Since most everything movable had changed, it was necessary to figure out what to put into the receiver extension to make it work correctly. Hence my little excursion into spring/weight "engineering". BTW, by benching the LWRC 16 inch piston upper and going with the 14.5 BCM lightweight profile I saved a measured 1 pound 4 ounces. A "carbine" should be light.
Most likely there is a combination which will work suppressed and unsuppressed. What happens with a USGI spring and the DPMS buffer?
I don't know. I tried a Blue spring (which is stiffer than a USGI) and DPMS buffer, and had bolt over base issues. The Noveske upper is gone. A Daniel Defense 12.5" will run suppr./unsuppr. with a Blue spring and Spikes T-2 buffer.
barrelwrench
09-27-10, 12:20
Yep, your right and it has worked for a long time. The milspec will not let you down and is made to be abused by way of lacking PM's in the field. I'm surprised the "why not a heavier BCG" didn't pop up. I also agree with you on the extractor springs...be careful or you end up with extractor bounce and other failures associated with a "to strong" spring. It is good to see so many replies and theories..it keeps us thinking.
Stay safe gents
vicious_cb
09-27-10, 15:09
So, for the record, what is your take on Sprinco's springs?
http://sprinco.com/tactical.html
They are excellent. I use the blue spring in all my guns. They have a much longer life than regular CAR springs.
They are excellent. I use the blue spring in all my guns. They have a much longer life than regular CAR springs.
What CAR spring did you compare them to?
How did you determine end of life?
What was the life of the regular spring and what was the life of the Springco spring?
I determine end of life by removing the lower from the upper, putting the lower onto a digital scale. Zero the scale. I then push down on the buffer until it moves a few millimeters. I then reject the spring if the scale reads below 5.3 lbs.
I actually found one in my collection today that was 4.8 lbs. I bet if someone sent me a box of take-out springs 90% of them would be good (by good, I mean within USGI specifications for a new spring).
What CAR spring did you compare them to?
How did you determine end of life?
What was the life of the regular spring and what was the life of the Springco spring?
I determine end of life by removing the lower from the upper, putting the lower onto a digital scale. Zero the scale. I then push down on the buffer until it moves a few millimeters. I then reject the spring if the scale reads below 5.3 lbs.
I actually found one in my collection today that was 4.8 lbs. I bet if someone sent me a box of take-out springs 90% of them would be good (by good, I mean within USGI specifications for a new spring).
==================================
Just wondering, how does that compare to measuring the length of the spring? What is the length of the 4.8# spring?
.
Well, I just pulled it out of the trash. It is 10 3/8 inches long.
My problems with the length method are:
1. The engineering drawing for the spring does not even have a length tolerance - just a reference length. What it has for pass/fail are forces at two compressed lengths.
2. Is it that hard to test with a scale like I did and be sure?
So yes, the length method was (hopefully) presumably designed to never pass a bad spring but to sometimes reject good springs. But since I am not sure they designed it that way, I would rather just test to the drawing and use force.
vicious_cb
09-27-10, 19:09
What CAR spring did you compare them to?
How did you determine end of life?
What was the life of the regular spring and what was the life of the Springco spring?
I determine end of life by removing the lower from the upper, putting the lower onto a digital scale. Zero the scale. I then push down on the buffer until it moves a few millimeters. I then reject the spring if the scale reads below 5.3 lbs.
I actually found one in my collection today that was 4.8 lbs. I bet if someone sent me a box of take-out springs 90% of them would be good (by good, I mean within USGI specifications for a new spring).
I have a clear plastic tube that fits a buffer spring. I marked several points for reference at 11.25" and 10.125". If the spring falls below the 10.125" I junk it. I used to use the CAR springs from Bravo and I found those to last around 3k rounds + maybe 500 dry fires before falling below the mark with noticeably less resistance when pulling back the CH(first thing I noticed). My oldest springco blue spring has seen 3k on a .223 carbine and perhaps 2.5 on my 5.45 carbine. So far it falls about 1/4 between my witness marks in my "gauge".
Ill probably run the spring in my 5.45 carbine to failure to see just how long it lasts.
Thomas M-4
09-27-10, 20:02
Well, I just pulled it out of the trash. It is 10 3/8 inches long.
My problems with the length method are:
1. The engineering drawing for the spring does not even have a length tolerance - just a reference length. What it has for pass/fail are forces at two compressed lengths.
2. Is it that hard to test with a scale like I did and be sure?
So yes, the length method was (hopefully) presumably designed to never pass a bad spring but to sometimes reject good springs. But since I am not sure they designed it that way, I would rather just test to the drawing and use force.
My LMT buffer spring dropped to 10 1/8'' and began to give me FTF with just over 2000 rounds. The sprinco has just under 2000 on it so far but it still feels like new I will keep track and see how it holds up.
I do feel that a SS spring would be the ideal choice for a service rifle.
For these springs that lasted 2000, 3000 rounds - I would love to know if they were out of spec to begin with.
By the way, stainless spring wire costs 2.75 times more than CS wire, yet you can buy a Colt buffer spring for $11 - less than some CS springs.
Thomas M-4
09-27-10, 20:49
For these springs that lasted 2000, 3000 rounds - I would love to know if they were out of spec to begin with.
By the way, stainless spring wire costs 2.75 times more than CS wire, yet you can buy a Colt buffer spring for $11 - less than some CS springs.
Mine was in spec at 500 rounds it dropped 3/4'' in 1500 rounds.
SS may be the Ideal service rifle spring but it doesn't make a good spring in general.
When I say 'in spec' I don't mean by length. There is no length spec on the drawing anyway.
I mean.... did the wire meet the minimum tensile strength of the military drawing? Was the wire of the correct certified material? Was the force at the two lengths within spec? Was the wire the correct diameter? Was the heat-treat done correctly? It is hard to know the answers to this stuff.
Thomas M-4
09-27-10, 21:10
When I say 'in spec' I don't mean by length. There is no length spec on the drawing anyway.
I mean.... did the wire meet the minimum tensile strength of the military drawing? Was the wire of the correct certified material? Was the force at the two lengths within spec? Was the wire the correct diameter? Was the heat-treat done correctly? It is hard to know the answers to this stuff. Buying a Colt spring will increase the chances of it being in spec.
No didn't send it off to to nasa for a failure report analyzes ;)
Next AR I will try your suggestion and see if I get better results.
SS may be the Ideal service rifle spring but it doesn't make a good spring in general.
Are we talking about the same thing here?
17-7 precipitation hardened wire, condition H900?
http://tiny.cc/nfcci
Thomas M-4
09-27-10, 22:09
Are we talking about the same thing here?
17-7 precipitation hardened wire, condition H900?
http://tiny.cc/nfcci
Sorry USGI .
FYI- I am using a Springco spring in my suppressed (AAC) SBR (11.5") as well and still had issues with bolt lock back- not cycling issues. Once I added an H2 I was GTG- even with Hornady TAP and other 55gr. I recently acquired an H3 and will be testing that as well. In it's current configuration it runs 100% suppressed and unsuppressed.
when I tried to shoot a Noveske 12.5" barrel with an M4-2000 it would not function with a standard USGI buffer spring and H buffer. The bolt cycled so fast that it frequently outran several revisions of the PMAG. It is probably for this reason that the Switchblock was created.
Sprinco can make all the claims they want, but their red spring allowed my SBR to cycle semi-automatically suppressed, without frequent bolt over base malfunctions. Of course YMMV. I hope that Vltor's new A5 system makes many suppressed SBR problems go away.
FWIW, Mike Pannone is a strong proponent of Sprinco (and Noveske, BCM, etc). If you read his real-world tests, he generally uses Sprinco springs.
Sorry USGI .
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.
Thomas M-4
09-28-10, 10:12
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.
I was unaware of USGI spring requirement being 17-7PH treatment.
Are colt springs 17-7 PH ? Never noticed that being listed.
I have not seen a Colt M4 spring drawing, but it is unlikely they downgraded the material used for the M16 spring.
Thomas M-4
09-28-10, 10:41
I have not seen a Colt M4 spring drawing, but it is unlikely they downgraded the material used for the M16 spring.
:thank_you2:
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.
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...
.
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.
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 :mad:) 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.
TwitchALot
10-02-10, 16:00
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.
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
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.
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
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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