AR Buffer Spring Shoot Out

[NWcityguy2]

I went out and bought some different AR Carbine buffer springs so I could compare them to each other. I wanted to do this because I often hear people compare stock springs, and throw around terms like mil-spec (insert your favorite AR company here) and commercial-spec (insert your least favorite AR company here). I honestly never seen anyone do a direct head-to-head comparison with various springs, nor have I myself ever seen much of a difference in them when comparing regular power springs.

For the springs, I have 6 to compare.



Spring 1: I bought this spring off Ebay, and made every attempt to buy one that was not advertised as being made in the USA. The only product description given was "Regular Carbine Buffer Spring for 556/223 USA Seller". I'm going to assume this spring comes from overseas. It is made of 0.067" wire and has 36 coils. It is also different from all the other springs in that it is coated with some sort of black enamel paint, which can be scraped away with a knife. Also, it does not have a reduced diameter at the ends, meaning the buffer spring slides in and out freely when outside of the buffer tube. It is labeled "ebay" in the photos. Cost: $5.35 (including shipping)

Spring 2: I bought this spring off Ebay as well, but it was advertised as being made in the USA. It was described as... "COLT CARBINE LENGTH BUFFER SPRINGS. HIGHEST QUALITY WIRE. 17-7 STAINLESS STEEL. THESE SPRINGS GET HEAT TREATED TO INDUSTRY STANDARDS AND ARE ALSO POLISHED ON THE OUTSIDE DIAMETER FOR A SMOOTHER FINISH AND ACTION. WE MANUFACTURE OUR BUFFER SPRINGS WITH THE END COILS SLIGHTLY SMALLER IN DIAMETER TO FIT SNUG ON THE BUFFER. - NO RATTLE. THE HIGHEST QUALITY BUFFER SPRINGS YOU CAN GET. MANUFACTURED BY DEPENDABLE SPRING COMPANY IN OREGON CITY, OREGON - USA"

The company does have a webpage, but it is not possible to buy directly from the company. It is made of 0.069" wire, has 37 coils and a satin finish. It is labeled "Ore" in the photos. Cost $7.50 (including shipping)

Spring 3: I bought this spring directly from Daniel Defense's website. It was advertised as "The Daniel Defense Carbine Buffer Spring for use in M4-type receiver extension tubes." It is made of 0.069" wire, has 37 coils and has a matte finish. Cost $14 (shipping included)



Spring 4: This spring came out of a PSA lower build kit. It is unused. It is made out of .068" wire and has 37 coils. Cost $3.95 if bought individually (shipping not included).

Spring 5: This is another PSA spring that has been used in one of my lowers. I don't have any firm round count, but at least a couple thousand. It is the same as Spring 4 in all respects.

Spring 6: This is a Tubbs Chrome Silicon Flatwire spring. The company rates it for 500,000 cycles, and it starts out about 20% stiffer than a carbine spring. It can also be used for rifle buffers and buffer tubes. This spring is an apples-to-oranges comparison, but I thought I'd throw it in because I already own one. It has about 5k cycles on it thus far. Cost: $25 (shipping not included).

To measure the spring, I created a guide rod for them to follow, and used a 5.5 lbs weight to compress them, along with a wood block to hold the weight. Below in the pictures you can see them both uncompressed and compressed. The compressed measurements are not meant to be taken as gospel, as I could get them to be taller or short by playing with the weight. However, every attempt was to make sure the springs were measured consistently, and were not bound or propped up.




As for shooting, I brought three types of ammo that is generally regarded as three different power levels. There is the (weak) Tulammo 55gr FMJ. Then I have (medium powered) brassed cased US made 223 pressure ammo in the Winchester 55gr FMJ. Finally, I have the (NATO Spec) 5.56 pressure M855 by Winchester. With each spring I will measure the ejection pattern and if the bolt locks back on the final shot. For the test gun, I will be using one of my ARs. It has a 16" mid-length barrel with a .078 gas port. The lower uses a carbine weight buffer. (As a note, I personally don't think ejection pattern is gospel, but it is something worth looking at all the same)




Spring 1 (Import Ebay Spring)
Tulammo: 3-4 O'clock ejection pattern, bolt held open.
Winchester 223: 3 O'clock ejection pattern, bolt held open.
Winchester 5.56: 3 O'Clock ejection pattern, bolt held open.

Spring 2 (Domestic Ebay Spring)
Tulammo: 4 O'clock ejection pattern, bolt held open.
Winchester 223: 4 O'clock ejection pattern, bolt held open.
Winchester 5.56: 3-4 O'Clock ejection pattern, bolt held open.

Spring 3 (Daniel Defense)
Tulammo: 4 O'clock ejection pattern, bolt held open.
Winchester 223: 4 O'clock ejection pattern, bolt held open.
Winchester 5.56: 3-4 O'Clock ejection pattern, bolt held open.

Spring 4 (New Palmetto State Armory Kit Spring)
Tulammo: 4 O'clock ejection pattern, bolt held open.
Winchester 223: 4 O'clock ejection pattern, bolt held open.
Winchester 5.56: 3-4 O'Clock ejection pattern, bolt held open.

Spring 5 (Used Palmetto State Armory Kit Spring)
Tulammo: 4 O'clock ejection pattern, bolt held open.
Winchester 223: 4 O'clock ejection pattern, bolt held open.
Winchester 5.56: 3-4 O'Clock ejection pattern, bolt held open.

Spring 6 (Tubbs Flatwire Chrome Silicon Spring)
Tulammo: 4 O'clock ejection pattern, bolt not held open.
Winchester 223: 4 O'clock ejection pattern, bolt held open.
Winchester 5.56: 4 O'Clock ejection pattern, bolt held open.


For the most part, the brass all landed in the same area.

Conclusion
All of the carbine springs functioned the same. The used Palmetto State Armory spring functioned the same as the new ones. The only spring that showed a difference was a Tubbs spring, which was marketed as a increased power spring and is indeed. It also adds noticeable stiffness to the charging handle, and reduces the "sprong" noise that the AR makes when firing.

My personal opinion
Don't pay too much for a buffer spring. If the spring isn't claimed to be increased power, and from a reputable company, then it most likely isn't. Also, these springs don't wear out very fast either. Really, the #1 responsibility these springs have is to return the action to battery. If you feel like your AR is punchy when firing, it might be worthwhile to look into an increased power buffer spring. I personally wouldn't base the decision on ejection pattern alone though, but that's me.

Hope it was informational.

 

[W.E.G.]

Thanks for all that work on the springs.

I have a large-ish batch of Q3131 (Winchester white box) from a purchase about ten years ago that seems to be under-pressured. It won't reliably lock-back the bolt on various AR's. I recently bought a very inexpensive 5-pack of springs from Damage Industries. I plan to clip one coil at a time on one of the new springs until the bolt will reliably lock back. I figure it can't hurt to sacrifice a spring to try to get some worthwhile use out of the anemic Q3131.

 

[NWcityguy2]

If it were me, and the only problem is bolt lock back, I'd just load the last round with a different ammunition.

 

[bfoosh006]

In case you are curious as to some of the actual spring weights

"Here's some good data on different spring force:


A2 (old) - 7.6lb closed, 14.5lb open
A2 (new) - 9.1lb closed, 16.7lb open
Tubb Flatwire - 10.5lb closed, 16.3lb open
Tubb .308 Flatwire - 13lb closed, 16.7lb open
SpringCo (White/standard) - 8.3lb closed, 16.3lb open
SpringCo (Red/Enhanced) - 10.5lb closed, 18.4lb open
SpringCo (Orange/Extra) - 13.9lb closed, 24.8lb open"

From David Tubb, here....

 

[Wreck-n-Crew]

Testing takes time and energy. Appreciate the Write up too.

I guess I only have oe curiosity and it's not related o the spring but the Tulammo. I've heard a lot of issues with people running Tulla in their AR's and have Extraction issues and stuck cases. Have you had any at all?

 

[NWcityguy2]

I personally have never had an issue with Tula, but I shoot very, very little factory ammo. Some ARs just don't run steel case well, and Tula could be inconsistent batch to batch. But for me, never a problem.

 

[chicharrones]

Thanks for the testing and reporting, NW!

 

[boom boom]

Ditto, thanks for some real world data.

 

[W.E.G.]

If it were me, and the only problem is bolt lock back, I'd just load the last round with a different ammunition.

That's a good suggestion.

My goal is to get the anemic ammo to "feel" more like normal ammo. With the current spring, I can tell that the buffer is not bottoming out during cycling, whereas normal ammo gives a distinctly different feel on each shot as the normal ammo bottoms the buffer during cycling.

I'm mostly shooting the Q3131 for offhand practice (single-feed, single shots) and some rapid-fire practice sitting-position on the SR-1 target.

I will post results when I have a chance to range-test.

 

[greyling22]

Thanks for all that work on the springs.

I have a large-ish batch of Q3131 (Winchester white box) from a purchase about ten years ago that seems to be under-pressured. It won't reliably lock-back the bolt on various AR's. I recently bought a very inexpensive 5-pack of springs from Damage Industries. I plan to clip one coil at a time on one of the new springs until the bolt will reliably lock back. I figure it can't hurt to sacrifice a spring to try to get some worthwhile use out of the anemic Q3131.

I had a blackout that wasn't cycling. I took 2 or 3 coils off the spring and it works great. No need to buy an overpriced reduced power spring. I think your plan to clip springs is a great one. Might want to paint the cut one to mark it so you don't get confused later on.

 

[Ramone]

Thanks for all that work on the springs.

I have a large-ish batch of Q3131 (Winchester white box) from a purchase about ten years ago that seems to be under-pressured. It won't reliably lock-back the bolt on various AR's. I recently bought a very inexpensive 5-pack of springs from Damage Industries. I plan to clip one coil at a time on one of the new springs until the bolt will reliably lock back. I figure it can't hurt to sacrifice a spring to try to get some worthwhile use out of the anemic Q3131.

OK, I have nothing to back it up, but somewhere I picked up the notion that trimming a coil spring makes it stiffer, not flexier.

I've got the notion that it's like shortening a lever. Again, I can't recall where I got the idea, but I'm interested in how it works out for you.

 

[clearcut]

If one was to cut a coil off the spring should be stretched back to it's original length. That would soften it.

CC