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Posted: 2/21/2025 5:40:35 PM EDT
[Last Edit: casktcrw][Edited]
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Colt copper spring ooooooonly. Oring OR insert? I HEARD mil runs oring + spring. Any truth to that? ^^no insert This is for middy 16s and car 14.5s |
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Originally Posted By casktcrw: Colt copper spring ooooooonly. Oring on insert? I HEARD mil runs oring + spring. Any truth to that? ^^no insert This is for middy 16s and car 14.5s Honestly, it wouldn't surprise me one bit if all three peices were used all at once because Sprinco says the donut can be used with their 4 coil spring and black insert, but isn't necessary. The Sprinco 4 coil feels a smidgen stouter than the Colt gold spring, IMO. Now, Sprinco advises against the donut with their 5 coil, but the 5 coil feels much stouter than Colt's gold spring. |
| Sprinco chrome silicon 5 coil is superior to everything else. |
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"KAC drip feeds their stockholm-syndrome-customer-base with bland and old products to keep them going with the Rolex company model of business to keep everything scarce and high priced" the_answer_is_42
"KAC drip feeds their stockholm-syndrome-customer-base with bland and old products to keep them going with the Rolex company model of business to keep everything scarce and high priced" the_answer_is_42
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Originally Posted By T-TAC: Bravo company Extractor spring, and black bumper. No need for the O ring. I like tis set up better than Colts copper spring. I put he BCM kit in every bolt I get. |
Wanted: Bikini cover for old school Trijicon 1x24 Reflex sight. IM please.
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Originally Posted By T-TAC: Bravo company Extractor spring, and black bumper. No need for the O ring. I like tis set up better than Colts copper spring. I'm very opinionated and you're not gonna change my decision to use the colt spring. The only question is what do I use with it. I appreciate the input and I'm sure I would offer the same. I'm just not going to use it. It does sound like the consensus is not to use the donut. I'll take out the donuts and original springs and put them in labeled baggies lol. I'm basically replacing all the coil springs w colt - all the ones that matter. |
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Originally Posted By jasonm4: Colt or FN gold colored extractor spring plus rubber insert but NO "O" ring. You can run an O ring if you want, but those springs mentioned are stronger and should be sufficient. Same goes for the Sprinco springs that some Microbest BCG's come with. So question was about running spring+oring NO INSERT. But i guess noone is doing that |
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Originally Posted By Raoul_Duke70: Black insert, Colt gold spring, donut goes in trash can. This. The "common practice" is when the extractor spring has compressed to the point that it is nearly the same height as the insert, it needs to be changed. Makes the insert twice as useful. |
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Nobody run o-rings anymore. I can’t believe something like that was contrived to fix extraction issues. The BCM extractor spring in my older Bushmaster with weak extraction pretty much solved all its issues. So much so that I pretty swapped all my AR extractor springs to BCM extractor springs. They all run like a top. All the o-rings went in the trash. |
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The thing is you probably won't notice any difference if you never had issues before. There's nothing wrong with swapping out the wear parts every so often just for peace of mind. Do you need to? Probably not but I guess what is more important than just changing parts is actually shooting. In my opinion, if you're buying the extractor because you're bored and want to fiddle with your rifle that instead you use that money and time to hit the range. |
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Originally Posted By BoomBoom: Nobody run o-rings anymore. I can’t believe something like that was contrived to fix extraction issues. The BCM extractor spring in my older Bushmaster with weak extraction pretty much solved all its issues. So much so that I pretty swapped all my AR extractor springs to BCM extractor springs. They all run like a top. All the o-rings went in the trash. Well somebody was out there saying the military was using them without an insert. I wish I could find it. |
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There seems to be some confusion about why the rubber insert is for, and why there was for a time an O-ring. The original bolt design of the AR-15 used a single 5-coil spring for the extractor. The limited space under the extractor dictated they use a spring with few coils and small diameter wire. If you know anything about spring design, you will know that that combination gives you extremely high stresses in the spring and a short unhappy life for the spring. If that was not bad enough, when the extractor snaps over the rim of the cartridge during chambering, because of the long lever arm of the extractor, it would slap the spring into coil bind. Consequently, the extractor spring did not last long. To fix the problem, a fluorosilicone rubber insert was placed inside the spring as "second spring". The rubber insert has "spring constant" just like a spring, thus adding to the assembly's constant. But unlike a wire spring, when compressed it will expand radially and fill the entire ID of the spring. This creates friction between the spring and the insert. Now, when the extractor slaps the spring the energy that use to over compress the spring and make them go it to coil bind, will be dissipated in the rubber insert. This spring was reduced one coil with the length remaining the same to allow for a smaller solid height. This combination of the 4 coil, 0.020" music wire spring (P/N 8448753) and the white, or later blue fluorosilicone insert (P/N 8448754) as Spring Assembly, P/N 8448755. When testing the M4 Carbine it was observed that the spring constant of the spring assembly ( After the M4 and M4A1 were fielded, failure to extract reports continued, prompting more action. In an effort to get immediate relief for the Special Warfare community NSWC Crane suggested the use of a fluorocarbon AS3209-007 size O-ring over the standard spring assembly. While the O-ring works, it is not optimal as it is actually too stiff, but standard O-rings are not offered in a wide variety of hardnesses. Around 2002, the new 4 coil The 12999901 spring and the 12972693 insert, or buffer, as it is now called, work better than the spring and o-ring because under small deflections the spring and buffer act independently of each other, but when highly compressed, the rubber insert fills the gaps in the coils and creates a higher spring rate than the spring rates of the two added. This makes the spring rate very non-linear, somewhat soft at low deflection, but very stiff at high deflections, unlike the O-ring which is high to start with and get even higher as compressed. In order the simplify the supply system, the new gold spring was tested in the M16A1 and M16A2, to see if the spring was backwards compatible. It was and the old designs were deleted from supply. And one last thing . . . . All of this was a full-automatic issue. In semi-automatic firing, the old M16A1 0.022" diameter wire 4-coil spring and blue insert gave no failures. For 99.9% of the people out there, 4-coil, 5-coil, black insert, O-ring, it's not going to make a difference. (But, stay away from chrome-silicon. That's just general advice, unless you are building a valve train in an engine, or need a spring made from wire .200" in diameter, C-S isn't as good as music wire.) |
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Originally Posted By the_AR-15_Junkie: In SAWs infamous reliability package he removes the Colt gold spring and puts in the spring you mentioned. A million years ago everyone said this was the spring to run so I ran it. I never had any issues so I still run it. IDK if there are better options out today. I do hear the Sprinco springs are a good choice. |
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Originally Posted By lysanderxiii: There seems to be some confusion about why the rubber insert is for, and why there was for a time an O-ring. The original bolt design of the AR-15 used a single 5-coil spring for the extractor. The limited space under the extractor dictated they use a spring with few coils and small diameter wire. If you know anything about spring design, you will know that that combination gives you extremely high stresses in the spring and a short unhappy life for the spring. If that was not bad enough, when the extractor snaps over the rim of the cartridge during chambering, because of the long lever arm of the extractor, it would slap the spring into coil bind. Consequently, the extractor spring did not last long. To fix the problem, a fluorosilicone rubber insert was placed inside the spring as "second spring". The rubber insert has "spring constant" just like a spring, thus adding to the assembly's constant. But unlike a wire spring, when compressed it will expand radially and fill the entire ID of the spring. This creates friction between the spring and the insert. Now, when the extractor slaps the spring the energy that use to over compress the spring and make them go it to coil bind, will be dissipated in the rubber insert. This spring was reduced one coil with the length remaining the same to allow for a smaller solid height. This combination of the 4 coil, 0.020" music wire spring (P/N 8448753) and the white, or later blue fluorosilicone insert (P/N 8448754) as Spring Assembly, P/N 8448755. When testing the M4 Carbine it was observed that the spring constant of the spring assembly (.020 dia wire spring and blue insert together) was too low, so the silicone insert was replaced by stiffer nitrile-butadiene insert. Buna-N being a hard compound made for a higher spring constant. The combination of the P/N 8448753 spring and the new stiffer insert (P/N 12972693) was the Spring Assembly, P/N 13004786. This was M4/M4A1 specific. After the M4 and M4A1 were fielded, failure to extract reports continued, prompting more action. In an effort to get immediate relief for the Special Warfare community NSWC Crane suggested the use of a fluorocarbon AS3209-007 size O-ring over the standard spring assembly. While the O-ring works, it is not optimal as it is actually too stiff, but standard O-rings are not offered in a wide variety of hardnesses. Around 2002, the new 4 coil .022" diameter music wire spring was approved (P/N 12999901), and when paired with the Buna-N Insert, P/N 12972693, it is the Spring Assembly, P/N 13004786. The spring was copper plated to make it easily distinguishable from the older spring. The 12999901 spring and the 12972693 insert, or buffer, as it is now called, work better than the spring and o-ring because under small deflections the spring and buffer act independently of each other, but when highly compressed, the rubber insert fills the gaps in the coils and creates a higher spring rate than the spring rates of the two added. This makes the spring rate very non-linear, somewhat soft at low deflection, but very stiff at high deflections, unlike the O-ring which is high to start with and get even higher as compressed. In order the simplify the supply system, the new gold spring was tested in the M16A1 and M16A2, to see if the spring was backwards compatible. It was and the old designs were deleted from supply. And one last thing . . . . All of this was a full-automatic issue. In semi-automatic firing, the old M16A1 0.020" diameter wire 4-coil spring and blue insert gave no failures. For 99.9% of the people out there, 4-coil, 5-coil, black insert, O-ring, it's not going to make a difference. (But, stay away from chrome-silicon. That's just general advice, unless you are building a valve train in an engine, or need a spring made from wire .200" in diameter, C-S isn't as good as music wire.) Thank you for the very detailed response. Your posts help me better understand the AR15 and why specs are what they are. |
Change is the only constant. - Heractilus
| The online drawings show the new spring 12999901 is .026" diameter wire. They show the last spring before the copper plated one 8448753 as .022" diameter. List the assembly of the newer buffer 12972693 and the 8448753 .022" dia. spring I think as assembly 12972692. |
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Originally Posted By j3_: The online drawings show the new spring 12999901 is .026" diameter wire. They show the last spring before the copper plated one 8448753 as .022" diameter. List the assembly of the newer buffer 12972693 and the 8448753 .022" dia. spring I think as assembly 12972692. Thx, fixed it. The 0.020" diameter goes with the old 8448514 spring. |
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Originally Posted By lysanderxiii: The 0.020" diameter goes with the old 8448514 spring. Was the 8448514 a 4 coil spring or just a later number for the 5 coil spring? I have never been able to find anything about the 8448514 spring other than it existed and the old 5 coil I found the measurements except for the wire diameter. Was the 5 coil diameter .020"? Thanks for any info you might have. |
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Originally Posted By j3_: Was the 8448514 a 4 coil spring or just a later number for the 5 coil spring? I have never been able to find anything about the 8448514 spring other than it existed and the old 5 coil I found the measurements except for the wire diameter. Was the 5 coil diameter .020"? Thanks for any info you might have. The 8148514 spring was the original 5 coil spring that came from Armalite; it is also known as Part Number 61568. The OD was 0.145", and the free length was 0.222", with a wire diameter of 0.020" you get a spring that produces 3.2 pounds at 0.140" and 4.3 pounds at 0.112", which is a little stiffer than the 8448753 spring, but it does not have the rubber insert to help. Also, a 5 coil spring with a wire diameter of 0.021 or greater will have a solid height is too high to fit under the extractor. |
| I put the print numbers in this spring calculator for a bunch of the springs in an AR a long time ago using the print material it called for and CS and decide to stick with the springs made from the spec. material. Both the extractor and ejector springs looked close to their limit in normal use to me looking at the results it gave. https://www.newcombspring.com/springulator/compression-spring-calculator |
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@lysanderxiii Can you talk a little but more about why CS springs are not recommended? From what I have read on this site, the biggest gripe I saw was that CS springs tend to rust. Most topics involving CS springs, however, were primarily about magazine springs. |
Change is the only constant. - Heractilus
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Originally Posted By RD20: When you say C-S isn't as good as music wire, are you specifically saying that due to CS being not as humidity resistant? Originally Posted By RD20: When you say C-S isn't as good as music wire, are you specifically saying that due to CS being not as humidity resistant? C-S spring are only better than music wire when the diameter of the wire is above 0.080" or the operating temperature of the spring is above 300° F, neither of which is the case for the extractor, or any other spring in an AR. Further, C-S is more susceptible to corrosion. C-S cost more than music wire. So, why use a spring that is not any better at being "springy", cost more and rusts more easily? If you are looking for a material for a internal combustion engine valve spring get a C-S spring, inside an engine it is hot, near 300° F, the spring is going to use very large diameter wire, and it sits in an oil bath so little risk of corrosion. Otherwise go with music wire, or 17-X stainless. For any spring with less than 0.080" wire, at room temperatures, you are not going to beat a music wire spring. Originally Posted By j3_: I put the print numbers in this spring calculator for a bunch of the springs in an AR a long time ago using the print material it called for and CS and decide to stick with the springs made from the spec. material. Both the extractor and ejector springs looked close to their limit in normal use to me looking at the results it gave. https://www.newcombspring.com/springulator/compression-spring-calculator Yes, the AR extractor spring is a very poor design, it needs to be about 5X longer, and about twice the wire diameter. 
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Originally Posted By lysanderxiii: C-S spring are only better than music wire when the diameter of the wire is above 0.080" or the operating temperature of the spring is above 300° F, neither of which is the case for the extractor, or any other spring in an AR. Further, C-S is more susceptible to corrosion. C-S cost more than music wire. So, why use a spring that is not any better at being "springy", cost more and rusts more easily? If you are looking for a material for a internal combustion engine valve spring get a C-S spring, inside an engine it is hot, near 300° F, the spring is going to use very large diameter wire, and it sits in an oil bath so little risk of corrosion. Otherwise go with music wire, or 17-X stainless. For any spring with less than 0.080" wire, at room temperatures, you are not going to beat a music wire spring. Yes, the AR extractor spring is a very poor design, it needs to be about 5X longer, and about twice the wire diameter. https://i.imgur.com/qOrlgnd.jpg GOTEM |
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