The 300 AAC Blackout round is a great option for urban tactical situations. It gives you the performance of a 7.62x39mm with standard-sized AR mags. There are dozens of ways to tune your AR, but the best way is to change up your buffer and spring. Follow our guide below for the best 300 Blackout buffer springs.
At a Glance: Our Top Picks for 300 Blackout Buffer Spring
- OUR TOP PICK: Brownells - AR-15 Buffer Retainer Springs
- RUNNER-UP: Geissele Super 42 Braided Wire Buffer & Spring Combo
- BEST BUDGET OPTION: Aero Precision AR15 Carbine Buffer Kit
Comparison Chart of the Best 300 Blackout Buffer Springs
Our Top Pick
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Why Do I Need to Replace or Upgrade the Buffer Spring?
In the simplest terms, you want just enough buffer weight and spring tension to lock the bolt back on an empty mag. If it is too light, you will not get any recoil reduction. If it is too heavy, your bolt may fail to lock back.
Standard carbine buffer systems are optimized for the 5.56 round, usually based on the specs of a standard military issue M4. If you have chosen to buy or build a rifle in 300 Blackout, chances are that not only is your caliber non-standard, but your rig is highly customized. Getting just the right weight of buffer and spring will require some trial and error.
Buffer Weight Options in the Market
Your recoil spring must be paired with the right buffer weight for your rifle. The buffer uses a combination of steel and tungsten weights to achieve the necessary weight. Different weights are identified by standard terms. Carbine weight refers to the standard three-ounce buffer used in mil-spec carbines. They work with a wide variety of ammunition. It is also great for mid-length setups.
A heavy or H1 carbine buffer weight is 3.8 ounces. It works best on over-gassed ARs.
The H2 carbine buffer weight ranges from 4.6 to 4.7 ounces. These are mainly practical for use with the recent fad of AR-15 pistols as they are not ideal for mid-length systems.
H3 carbine weight is 5 to 5.4 ounces. This can be used with the 300 Blackout but is more suited to the 458 SOCOM.
Rifle-length buffers are completely different animals, with a standard weight of 5 ounces. They are not interchangeable with the carbine systems.
What Makes a Great 300 Blackout Buffer Spring?
There are dozens of variables to consider when selecting the right buffer and spring tension for your 300 Blackout AR-15. Don't assume that it is as simple as matching the right buffer system to your caliber.
As with many rounds, the 300 Blackout comes in both sub and supersonic varieties in a range of bullet weights. Each will work best with a different spring tension.
Other variables include barrel length, gas port size, muzzle device, bolt carrier group weight, and more. Carbine springs have 37 to 39 coils and rifle springs should have 41 to 43. Carbine recoil springs must be over ten inches to be serviceable, even after losing length due to regular use.
Rifle springs must be over twelve inches. Most recoil springs are a solid, round wire steel alloy.
Flat wire springs are supposed to have better longevity and reliability.
Braided wire springs offer better harmonic dampening.
Review of the Best 300 Blackout Buffer Springs
With so many options and variables, it can be hard to choose the best 300 AAC Blackout recoil spring. Luckily, we've done the hard work for you, so follow our guide to the best options on the market today.
Brownells - AR-15 Buffer Retainer Springs
As one of the largest firearms retailers in the country, Brownells has the market data and research to know which firearms accessories and components work and which ones don't. They produce many of their own products, both components and complete firearms.
Anything with the Brownells name on it tends to offer outstanding value for money. These are classically styled springs that live up to Brownells’ reputation for providing value for money. This is an excellent option to have a few disposable back-up springs around so that you can assert your alpha status by being the guy who comes to the rescue when your buddy's rig stops functioning.
The material and construction are guaranteed to be equal in quality to those of original equipment manufacturer springs. If you have a nice, older, modern sporting rifle that isn't running like it used to but still has a lot of sentimental value, you've got nothing to lose by tossing in one of these springs to bring it back to life.
Whether you just want a cheap spring, have an old modern sporting rifle to resuscitate, or just want to keep a spare spring or two around, this option is for you. The top features of this spring are the price and the solid construction.
Geissele Super 42 Braided Wire Buffer & Spring Combo
Geissele is a Pennsylvania company that has cultivated a formidable reputation for itself in the modern sporting rifle world. The Geissele name elicits immediate respect down at the range. The Geissele Super 42 Spring has been engineered to enhance the function and reliability of your modern sporting rifle.
It is a braided spring, with three separate wires like that of the classic German MG42 machine gun. This design dampens harmonics and absorbs energy because each wire flexes independently. This also makes your firearm more reliable by decreasing the chances for spring failure and displacing excess energy.
The braided design has a reduced tendency to lose its strength and length over time. This is a carbine-length spring best used with supersonic 300 Blackout ammo. As a relatively strong spring, it requires the energy transfer from supersonic rounds to function well. The extra spring strength also provides additional reliability with bad ammo or a dirty gun. One nice feature is a reduction in the twangy spring noise you get with legacy springs.
Given the reputation of Geissele and the outstanding design and construction of this spring, this is an option that will impress you and anyone next to you at the range. The top features are its reliability and smooth, quiet function. This spring is truly hard to beat.
Aero Precision is a company out of Tacoma, Washington that specializes in precision machining with a focus on the modern sporting rifle. This option is not just a simple spring but a full buffer kit. It includes a six-position mil-spec 7075-T6 aluminum buffer tube, a carbine buffer (3 oz.), a buffer spring, an end plate, and a lock nut. Note that it does not include a stock.
This is another great option to give an older modern sporting rifle a new lease on life. You will be able to rest easy with the knowledge that all of the components are specifically designed and tested to work well together. This kit is tested to cycle smoothly with no sticking. At about 9.8 ounces, it is also a great lightweight option.
It is precision-machined to fit your AR solidly. In most cases, the fit will be so snug that there will be no lateral movement at all. Despite being made here in the U.S.A., this a great value for money option.
This is an affordable, full buffer system that will bring life to any old modern sporting rifle. The top features are the fact that this is a complete kit and the tight fit to the receiver. If you want a hassle-free, high quality, and lightweight buffer system for a great price, this is the perfect option.
4. Guntec USA AR-15 CAR 42 Braided Wire Buffer Spring Combo Kit
Guntec is a company operating out of Arizona. It has been engineering, producing, and distributing tactical firearm accessories since 1989. This is a newly-designed braided spring based on the spring used in the classic German MG42 machine gun.
The braided design gives you superior harmonic dampening as each braided wire compresses separately. Basically, this means that your barrel will vibrate less during firing, giving you greater accuracy. This is a carbine-length spring. If you have a collection of upper receivers in different calibers, you will be happy to know that this spring can work with 300 Blackout, 5.56/.223, 7.62x39, 9mm, and 244 Valkyrie.
This spring is manufactured with the tightest possible tolerances to give you the smoothest possible cycling. One of the best features of this spring is the noise reduction it offers thanks to its tight compression.
Unlike most springs, this one runs silently. It can also ameliorate cycling problems and reduce your felt recoil. It includes a standard carbine three-ounce buffer. This spring is eleven-and-a-half inches long and weighs 1.7 ounces.
Braided wire springs are the latest big thing in buffer system updates. The benefits are real. The top features of this spring are the harmonic dampening and the noise reduction. This is a hard option to beat for the most cutting-edge AR build.
5. PSA PA10 Carbine Buffer Spring
Operating out of South Carolina, Palmetto State Armory is a veteran-owned manufacturer of firearms and firearms components. PSA is also one of the nations larger firearms and firearm component distributors. This gives them a lot of data on what products work, which products provide satisfaction, and what products people want.
PSA uses all of this data and knowledge to make their own branded firearms products some of the best and most affordable options you can find. The PSA PA10 buffer spring is a classic round wire buffer spring for use in carbine buffer systems. Although it is designed specifically for use with Palmetto State Armory's PA-10 and PTAC Tac-10 lower AR receivers, it can be used with any carbine-sized buffer system.
It is, however, optimized for use with .308 caliber AR-10 style systems. As such, it will work better with supersonic than subsonic 300 Blackout ammunition. The total length of this spring is eleven-and-a-half inches and it has 31 coils. Overall this is a great, affordable option designed for AR-10 style carbines.
This is a great option, given the outstanding value for money and Palmetto State Armory's enviable reputation for quality. The top features of this spring are the optimization for AR-10s and the classic design.
No matter what kind of 300 AAC Blackout AR-15 setup you have, there is a recoil spring on our list for you. It might take some trial and error to find the best option because there are so many variables and it is a matter of taste. Stay safe and happy shooting!