AR-15 Buffer Weight Guide: Chart, H2 vs H3 and Which Buffer Your Build Needs

Last updated and checked November 8, 2026 · By Nick Hall, AR-15 builder who has tuned buffer weights across multiple gas systems

This post contains affiliate links. If you click and buy, I may earn a small commission at no extra cost to you. Full disclosure.

How I checked this guide: every buffer weight here is the maker’s own listed figure, the sources are linked at the bottom, and every price comes from the live cards on this page, checked the day it was updated.

Table of Contents

A buffer is one of those AR-15 parts most people never think about until something goes wrong. Your rifle short-strokes and won’t lock back on empty. Or it beats itself to death with excessive bolt velocity. Both problems trace back to buffer weight, and the fix is cheap: a plain carbine buffer starts around $9.99 on the card below, and a tungsten H2 around $41.49.

I’ve tuned more buffers than I can count across carbines, pistols, and rifle-length setups. It’s one of the easiest and most impactful upgrades you can make. Here’s everything you need to know to pick the right one.

Quick Answer: Which Buffer Weight Does Your AR-15 Need?

Match the buffer to the gas system and barrel, then go one step heavier if you add a suppressor. A 16 inch mid-length rifle starts on a standard carbine buffer. A 16 inch carbine-gas rifle starts on an H. A 10.3 to 11.5 inch carbine-gas SBR or a pistol-gas AR pistol starts on an H2. The H3 is a correction for a gun that is still over-gassed on an H2, not a default. A rifle-gas 18 to 20 inch gun takes a rifle buffer in a rifle-length tube, which is a different part altogether.

The four carbine-length weights are BCM’s listed figures and the rifle buffer is Aero Precision’s. Other makers land within a tenth or two of them.

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What the Buffer Does

The buffer sits inside the buffer tube, which the manuals call the receiver extension, right behind the bolt carrier group. When you fire, gas pushes the BCG rearward. The buffer absorbs that energy and, with help from the buffer spring, sends the BCG forward again to strip a new round from the magazine and chamber it. If you want to see where it sits among everything else, our AR-15 parts list lays out the whole lower.

The AR-15 remains the most popular rifle platform in America. An NSSF report released in February 2026 puts more than 32 million modern sporting rifles, AR-15s and AK-pattern rifles together, in civilian hands. That’s a lot of buffers.

The weight of the buffer decides how fast the BCG moves rearward and how much energy it takes to cycle. A heavier buffer means slower, softer cycling. A lighter one means faster, snappier cycling. Getting the weight right is about finding the balance between reliable cycling and smooth operation.

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AR-15 Buffer Weight Chart

Here’s the standard weight progression for carbine-length buffers, the type that goes in almost every collapsible-stock AR-15 and AR pistol, plus the two buffers that look similar and aren’t interchangeable with them.

One naming note before you shop, because it trips people up. H and H1 are the same buffer. Both mean the 3.8 oz heavy buffer with one tungsten weight, and makers use the two labels interchangeably, so an “H1” listing is not an upgrade over an “H”. There is no mil-spec H4 for a carbine tube, whatever a few charts online suggest. A few makers do sell one, like PWS’s 6.8 oz steel-body H4, but that’s a maker label, not a standard. The designations that mean the same thing from every maker are carbine, H/H1, H2 and H3.

A few notes on the rows that aren’t mil-spec. The heavy steel-body row used to read “HSS, 6.5 oz, 3 stainless steel” here, which can’t be right: three steel weights in a carbine body is the 3.0 oz carbine buffer. The weight class is real, though, and PWS sells it as an H4 steel-body buffer at 6.8 oz. AR-10s run their own buffers, so none of this chart applies to a .308 gas gun.

Rifle buffers are longer, at about 5.0 to 5.3 oz, and only work in rifle-length A2 buffer tubes. They are not interchangeable with carbine buffers. Don’t try to put a rifle buffer in a carbine tube. It won’t fit and could cause problems. The tube decides it, not the stock: you can buy adjustable stocks for rifle tubes, and an AR pistol with no stock at all still takes a carbine buffer. If you’re choosing between the two, our AR-15 stock guide covers which stocks fit which tube.

Is an H1 the Same as an H Buffer?

Yes. An H1 is not one step heavier than an H. Both are the 3.8 oz buffer with one tungsten and two steel weights, and you’ll see the same buffer listed as “H”, “H1” and “H Weight” depending on the store. The one place the number means something else is the VLTOR A5 line, where A5H1 is a 4.56 oz A5 buffer. More on that below.

H2.5 and H4 Buffers

Both exist, and neither is a mil-spec class. The Takedown Tools lists its H2.5 at 5.1 oz, which slots between an H2 and an H3 for a rifle that’s a little rough on an H2 and a little sluggish on an H3. On the heavy end, PWS lists its Enhanced Steel Body Buffer, Carbine, H4 at 6.8 oz, and VLTOR’s A5H4 is 6.83 oz but only fits an A5 tube. If you’re past an H3 on a direct-impingement 5.56, I’d look at gas before buffer weight, which is what the adjustable gas block section below is about.

How to Identify and Weigh Your Buffer

You don’t need to take anything apart to find out what you have. Pull the buffer and spring out of the tube, then:

1. Check the rear face. Some buffers carry their class stamped there. VLTOR’s A5 buffers do, for example, and an A5H2 face reads “A5-2”. No stamp is common, so don’t read anything into a blank face.
2. Weigh it on a kitchen scale. About 3.0 oz is a carbine buffer, 3.8 oz an H, 4.6 oz an H2 and 5.4 oz an H3. Anything near 5 oz and noticeably longer is a rifle buffer.
3. Count the swaps if you’re curious. Each steel weight swapped for tungsten adds about 0.8 oz on BCM’s figures: 3.0, 3.8, 4.6, 5.4. So a 4.6 oz buffer is two tungsten and one steel, without taking it apart.

That’s also how you spot a buffer sold as “similar weight to H2”. I’ll get to that one in the H2 section.

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What Does an H2 Buffer Weigh?

An H2 buffer weighs 4.6 oz. Some makers list anywhere from 4.4 to 4.7 depending on how they finish the weights, and anything in that band is a real H2. PWS lists its own H2 at 4.4 oz, and a 4.5 oz suppressor version. Inside the tube it is two tungsten weights and one steel, against the carbine buffer’s three steel.

It is the most useful buffer on this page for most people. If you have a 16 inch carbine-gas rifle that runs hot, a 10.3 to 11.5 inch barrel, or a can on the end, the H2 is the one to try first. It is heavy enough to calm a violent carrier without being so heavy that the rifle stops locking back on the last round.

One thing to check before you buy. A lot of cheap buffers are sold as “similar weight to H2” rather than as an H2. When I ran the live prices for this update, the cheapest result on the H2 search was a $9.99 buffer listed at 4.9 oz, described as similar to an H2. It is a usable heavy buffer and it is not an H2: it is 0.3 oz over spec, and it gets that weight from steel rather than tungsten, so the mass sits differently in the tube. If you are tuning a rifle by swapping one known quantity for another, buy the actual spec. If you just want it heavier, the cheap one will do that. The card below filters it out.

What Does an H3 Buffer Weigh?

An H3 buffer weighs 5.4 oz, and some makers list theirs at 5.5 or 5.6. It is three tungsten weights, no steel, which is why it costs roughly a third more than an H2: about $54.04 against $41.49 on the cards today.

The H3 is a fix for a specific problem rather than a general upgrade. Reach for it when the rifle is clearly over-gassed and the H2 was not enough: a short suppressed barrel, a pistol-gas build, or brass landing forward of three o’clock with an H2 already fitted. On a normally gassed 16 inch rifle an H3 is heavy enough to short-stroke the action, so do not fit one hoping it will smooth things out. Heavier is not better. Heavier is a correction.

H2 vs H3 Buffer: Which One Do You Need?

If you’re choosing between the two, start with the H2. It covers more builds, and stepping up to an H3 later costs one buffer. Going the other way tends to mean you bought the H3 first and the rifle stopped locking back.

The prices in that table are the lead rows on the two cards above, so check the cards for today’s numbers.

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A Word on the A5 System

Search for buffers and you will run into VLTOR A5 parts sitting alongside the carbine ones. They are not interchangeable and the labels do not mean the same thing.

The A5 is a different buffer system. VLTOR built it around an intermediate receiver extension, 3/4 inch longer than a carbine tube and still made for a collapsible stock, plus a longer A5 buffer and a rifle-length spring, not a carbine spring. VLTOR’s own warning is blunt: the RE-A5 tube isn’t compatible with carbine buffers or carbine springs, and a carbine buffer in an A5 tube over-travels, which can damage the firearm. So an A5 buffer is physically longer than a carbine buffer, it will not fit a carbine tube, and none of the three A5 parts mixes with carbine parts.

The naming also overlaps confusingly: an A5-labelled “H2” is not a carbine H2. One in our own price data is listed at 5.3 oz, where a carbine H2 is 4.6. VLTOR’s full A5 range runs A5H0 3.80 oz, A5H1 4.56, A5H2 5.33, A5H3 6.08 and A5H4 6.83 oz, and VLTOR calls the A5H2 its standard starting weight. If your rifle has a standard collapsible stock on a carbine tube, everything else on this page applies to you and the A5 parts do not.

Carbine vs Rifle vs A5 Buffer Tubes

This is the table that settles most “will it fit” questions. The buffer, spring and tube are a matched set, and the tube length decides which set you have.

Lengths are Aero Precision’s for the carbine and rifle buffers and VLTOR’s for the A5. Sprinco makes the same point from the spring side: its rifle-length Green spring is the one for A1/A2 rifle tubes and for VLTOR A5 tubes with their 4 inch A5 buffers. AR-10s use their own tubes and buffers again, so treat them as a separate system.

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How Buffer Weight Affects Cycling

Think of it this way: the gas system pushes the BCG back with a fixed amount of force, set by barrel length, gas port size, gas system length and ammo. The buffer is the resistance on the other end. More resistance from a heavier buffer means slower bolt carrier movement. If you want the mechanics behind that push, our direct impingement vs piston guide walks through it.

Slower bolt carrier movement means softer recoil impulse, less bolt bounce, less wear on the receiver extension, gentler extraction that’s easier on your brass, and quieter operation. It also means less margin for cycling with weak ammo or when the gun is dirty.

The goal is to run the heaviest buffer that still lets the gun cycle reliably with your chosen ammo in all conditions. You want the bolt to lock back on the last round consistently. If it doesn’t, your buffer is too heavy or your gas system is too restricted.

Matching Buffer to Gas System

Your gas system length determines how much gas hits the BCG, which directly affects what buffer weight you need. Shorter gas systems like pistol and carbine send more gas at higher pressure, so they need heavier buffers. Longer ones like mid-length and rifle are gentler and can run lighter buffers.

These are starting points, not absolutes. VLTOR treats 10.3 to 14.5 inches as carbine-gas territory, which is why the 10.3 inch Mk18 length sits with the carbines here and not the pistols. Your specific barrel’s gas port size, your ammo, and whether you run a suppressor all affect the ideal weight. Start with the recommendation and adjust based on function testing. For more on gas system pairing, see our gas system length guide, and our AR-15 barrel length guide covers which gas length comes on which barrel.

AR Pistol and SBR Buffer Weight by Barrel Length

Short barrels are where buffer weight matters most, because a short carbine or pistol gas system dumps a lot of gas fast. Here’s where I’d start on the common lengths, using the same rules as the gas table above. Builds on these lengths are mostly AR pistols or registered SBRs.

If the brass still lands forward of three o’clock on the suppressed column, that’s the point where an adjustable gas block makes more sense than chasing an H4. And on a 300 Blackout pistol, read the caliber section first, because subsonic loads change the answer.

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Buffer Weight for a Suppressed AR-15

Running a suppressor increases backpressure significantly, and our how suppressors work piece explains why. That extra gas hitting the BCG means you need a heavier buffer to slow things down. If your unsuppressed gun runs well with an H buffer, you’ll probably want an H2 when you add a can.

I run H2 buffers on almost all my suppressed carbines and they work well. Some really over-gassed setups, like a short barrel plus a suppressor, need an H3. The signs of being over-gassed while suppressed include brass getting flung 20+ feet, primer cratering, and the charging handle smacking you in the face. If you haven’t picked a can yet, our best suppressors list is a good place to start.

A better solution for dedicated suppressor use is an adjustable gas block. That lets you tune the gas at the source instead of trying to compensate with buffer weight. But if you’re swapping between suppressed and unsuppressed, buffer weight is the simpler adjustment.

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Troubleshooting: Short-Stroking

Short-stroking means the BCG doesn’t travel far enough rearward to pick up the next round or lock the bolt back on empty. Symptoms include failure to feed and failure to lock back. The fix is a lighter buffer.

Before swapping buffers, check your gas system first. A clogged gas port, loose gas block, or gas tube leak can all cause short-stroking that no buffer change will fix. Also try different ammo. Steel-cased cheap stuff generates less gas than brass-cased NATO-spec loads.

If the gas system checks out, drop down one buffer weight. Running an H2 and short-stroking? Try an H. Still short-stroking? Go to a standard carbine buffer. If a carbine buffer still doesn’t fix it, the problem is your gas system, not your buffer.

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Troubleshooting: Over-Gassing

Over-gassing is far more common than short-stroking, especially on factory AR-15s. Manufacturers drill gas ports slightly oversized to ensure reliability with the widest range of ammo. The result is a gun that runs but beats itself up in the process.

Signs of over-gassing: brass ejecting at 1-2 o’clock when it should land around 3-4 o’clock, excessive recoil, primer cratering, chewed-up brass, and excessive bolt carrier velocity that wears out the buffer tube and lower receiver. The easy fix is a heavier buffer. The better fix is an adjustable gas block.

I use the ejection pattern as my primary diagnostic. Brass at 4 o’clock is ideal. At 3 o’clock, you’re slightly over-gassed but fine. At 1-2 o’clock, you need a heavier buffer or gas adjustment. At 5-6 o’clock, you’re under-gassed and need a lighter buffer.

The clock is read with the deflector as the center and three o’clock straight out to the right of it, the same convention Gun Digest uses. Brass flying between three and one o’clock is getting more gas than brass flying between three and five. Shoot it clean, with the ammo you actually use, before you change parts.

Buffer Problems: Symptom and Fix

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Adjustable Gas Blocks as an Alternative

An adjustable gas block lets you control gas volume at the source. You can tune it for minimum reliable cycling, which gives you the softest recoil, least wear, and best brass condition. It’s a better long-term solution than stacking buffer weight.

Superlative Arms, SLR Rifleworks, and Wojtek Weaponry make good adjustable gas blocks. The Superlative bleed-off design is my favorite because it vents excess gas instead of restricting it, which keeps the gas system cleaner. Pair one with whatever buffer gives you reliable cycling on the lowest gas setting. The Superlative card below starts around $80.99 today.

The downside of adjustable gas blocks is complexity and the possibility of the adjustment moving under recoil or heat. For a duty or home defense gun, I’d rather run a fixed gas block with the right buffer weight. For a range or competition gun, adjustable all the way. Our best AR-15 parts and accessories guide covers top gas block picks.

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Buffer Spring Types

The buffer spring matters just as much as the buffer weight, and it’s the part most people forget about. A standard carbine spring works fine for most builds, but upgraded springs can make a noticeable difference in feel and consistency.

Standard Carbine Spring

The milspec spring that comes in every parts kit. It works. It’s cheap. It also makes that annoying “sproing” sound when you charge the rifle. Replace it when it gets weak, somewhere around 5,000 to 10,000 rounds, or sooner if it’s noticeably shorter than a new one.

Sprinco Springs

Sprinco color-codes its springs by power, and the names matter, because two of them get mixed up a lot. White is the standard spring, the same load as a brand new mil-spec carbine spring. Blue is Enhanced, about 15% more than White. Red is Extra power, about 25% more. Green is not a carbine spring at all: it’s Sprinco’s standard-power rifle-length spring, the one for A1/A2 rifle tubes and VLTOR A5 tubes. They’re chrome silicon wire, which lasts longer than standard music wire. I run Sprinco blues on most of my carbines and like them a lot.

All seven are Sprinco’s own names and percentages from its buffer spring page. The card below lists the AR-15 colors, all at $19.95 today.

Geissele Super 42 Buffer and Spring Combo

If you’d rather buy the buffer and spring as one matched pair, Geissele’s Super 42 combo pairs a braided-wire spring with a buffer in H1, H2 or H3 weight. It’s the easiest way to fix the sproing and the weight in one box, and the card starts around $63.99. Check which weight you’re getting, because the listings mix H1, H2 and H3 versions.

JP Enterprises Silent Captured Spring

This is the top shelf for buffer and spring combos. It replaces both the buffer and spring with a single captured unit. No sproing sound, very smooth cycling, adjustable weight with different internal configurations. It’s about $190 to $220 at today’s dealers, and I think it’s worth it for a precision or competition build. I’ve been running one in my match rifle for three years and it’s still going strong. JP sells replacement spring packs and O-rings for it, so it’s a serviced part, not a disposable one.

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Hydraulic and Specialty Buffers

Hydraulic buffers like the KynSHOT use fluid to dampen bolt carrier movement. They reduce felt recoil noticeably and eliminate bolt bounce. They’re popular in competition guns and suppressed builds where smooth cycling is a priority. One catch: every AR-15 KynSHOT in our price data is the rifle-length, fixed-stock version, so it’s for an A2-tube rifle, not a carbine tube. The card below is that version, from about $114.56.

The Armaspec Stealth Recoil Spring is another captured system that uses a dual spring design. It’s more affordable than the JP SCS and does a good job eliminating the sproing sound. It’s a solid mid-price option, from about $62.09, and Armaspec sells it in C, H, H2 and H3 weights so you can keep your tuning.

For most shooters, a standard buffer in the right weight plus a Sprinco spring is all you need. The fancy captured systems are nice-to-haves that make a good gun feel great, but they’re not necessary for reliable function. Build your AR-15 with the basics first and upgrade later.

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Buffer Weight for Specific Calibers

Different calibers on the AR-15 platform have different buffer requirements. Here’s how the common ones break down.

9mm AR and PCC Buffer Weight

A 9mm AR is a different animal. Most 9mm uppers are straight blowback, with no gas system at all, so the buffer and the bolt’s own mass are the only things holding the action shut. That’s why a normal H2 is too light. KE Arms, which makes 9mm lowers, puts the minimum at 5.4 oz to avoid damaging an aluminum or polymer lower in a 9mm blowback gun, and says it runs 8 to 10 oz buffers in its own 9mm rifles. Drop a 4.6 oz H2 into an AR9 and you’re hammering the lower every shot.

Buy a dedicated 9mm buffer: Luth-AR’s 9mm body is 5.45 oz, and the card below starts around $19.99. Kits up to 10 oz exist for 9mm, .40 and .45, and KE Arms puts .45 ACP blowback at an 8 oz minimum. Sprinco lists its Red spring as common in 9mm. If you’re shopping complete guns, see our best 9mm carbines and 9mm AR pistols, and the competition PCC list if you’re heading for a PCC division.

300 Blackout Buffer Weight

For 300 Blackout, especially if you’re running both supersonic and subsonic loads, an H buffer is a good compromise unsuppressed. Supers will cycle fine, and most subs will too, though some really quiet subsonic loads might need a carbine buffer. An adjustable gas block makes this much easier to tune.

Suppressed is where 300 BLK earns its reputation, and it flips the problem. Subsonic loads have the least gas to spare, while supers through a can are the most over-gassed combination you’ll run. If you shoot both through a can, set the buffer so subs still lock back and use the gas block to tame the supers. Most of these guns are short 300 Blackout AR pistols or 300 BLK uppers on pistol gas, and our 300 Blackout vs 5.56 comparison covers why people build them.

6.5 Grendel, 6.8 SPC and .22 LR

6.5 Grendel and 6.8 SPC work best with standard carbine or H buffers. Sprinco lists its Red spring as common in both. .22 LR drop-in conversions are a different case: the common ones replace the bolt carrier with a self-contained blowback unit, so the buffer barely matters. Dedicated .22 LR uppers follow their maker’s buffer advice.

For the standard 5.56/.223 AR-15, stick with the recommendations in the gas system chart above. If you’re exploring alternative calibers, our AR-15 caliber guide covers the calibers themselves, and the gas system and spring advice here carries over.

Browse All AR-15 Parts →

Want to compare what a whole rifle or upper costs before you start swapping parts? Our gun price check searches the same retailers as the cards on this page.

Frequently Asked Questions

Sources

• BCM: carbine 3.0 oz with 3 steel weights, H 3.8 oz with 1 tungsten and 2 steel, H2 4.6 oz with 2 tungsten and 1 steel, H3 5.4 oz with 3 tungsten, from the product pages
• Aero Precision: AR15 rifle buffer, 5.0 oz, 6.0 in long; carbine-length buffer 3.25 in
• VLTOR: A5 buffer system, RE-A5 receiver extension 3/4 in longer than carbine and 7 15/16 in overall, rifle-length spring, carbine-parts warning, A5H0 to A5H4 weights
• Sprinco: buffer spring colors and loads, Yellow, White, Hot White, Blue, Red, Orange and Green
• PWS: Enhanced Steel Body Buffer, Carbine, H4, 6.8 oz; H2 4.4 oz and 4.5 oz suppressor weight
• KE Arms: 9mm blowback buffer minimum of 5.4 oz and .45 ACP minimum of 8 oz
• The Takedown Tools: H2.5 buffer, 5.1 oz
• Gun Digest: AR Basics, Initial Diagnosis of AR Gas System Issues, the ejection clock
• Shooting Industry / NSSF: 32 million modern sporting rifles in circulation