Blackout, 8.6 Blackout, 300gr Sierra MatchKing Subsonic Ammunition, 80 Round Bucket

The 8.6 Blackout 300gr Sierra MatchKing subsonic bucket puts 80 match grade rounds on your bench for $109.96, about $1.37 a round. It is the load we recommend for zeroing a new 8.6 Blackout rifle, tuning a suppressor and shooting groups, because the 300gr MatchKing is the most consistent bullet in the caliber’s subsonic range. It is not a hunting round, and this page explains why as well as what it does well.

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What the bucket gives you

Eighty rounds in a resealable bucket, loaded on the same line and to the same inspection standard as the 20 round retail box. Buying the 8.6 Blackout 300gr Sierra MatchKing load in bulk saves about 30 percent against four boxes, and the bucket itself is the container most shooters end up carrying to the range anyway.

Every round uses factory new brass, a match primer and a charge tuned so the bullet leaves a 12 inch barrel just above 1,000 feet per second. Overall length and neck tension are held to the tolerances a match bullet deserves. That consistency is the whole point of paying for a MatchKing rather than a plain open tip bullet.

The Sierra MatchKing bullet

Sierra’s MatchKing family has set more national records than any other match bullet line, and the 300 grain .338 caliber version is one of the heaviest. It is a boat tail hollow point with a long secant ogive, a thin, uniform jacket and a lead core drawn to tight weight tolerances. Nothing about the design is meant to expand. Everything about it is meant to fly the same way every time.

In 8.6 Blackout that matters because subsonic bullets spend a long time in the air. A round that takes a third of a second to reach 100 yards has more time for wind to act on it than a supersonic bullet. The 300 grain MatchKing’s high ballistic coefficient of about 0.750 means it resists that drift far better than a lighter subsonic.

Velocity, drift and drop

The figures are rounded from our 8.6 Blackout ballistics chart. Run your own barrel and zero through the ballistics calculator for a card you can tape to the stock. Because the bullet’s coefficient is so high, its wind drift at 200 yards in a 10 mile per hour crosswind is only about 8 inches, roughly half what a 220 grain 300 Blackout subsonic shows at the same range.

The 8.6 Blackout 300gr Sierra MatchKing load also holds velocity unusually well. It arrives at 200 yards still doing around 950 feet per second, which is why it remains stable and accurate past the distances where lighter subsonics start to wander. Our ballistics guide explains the physics in more depth.

What to use it for

Zeroing. A new rifle, a new scope, a new suppressor, or a barrel change all call for a confirmed zero, and the 8.6 Blackout 300gr Sierra MatchKing bullet removes the ammunition as a variable. Group testing. If you want to know what your barrel can do, this is the load to find out with. Suppressor tuning. Point of impact shift with and without the can is easiest to measure with the tightest shooting round you own.

Practice. At $1.37 a round the bucket makes regular subsonic practice affordable, and shooting the same weight class as your hunting load keeps your holds familiar. Competition. Subsonic precision matches and suppressed rifle events are growing, and the 300 grain MatchKing is the obvious choice. Browse the whole 8.6 Blackout ammo range to see how it fits alongside the hunting loads.

Why not for hunting

A MatchKing’s hollow point is a manufacturing artefact, not an expansion feature. At subsonic velocity the bullet behaves like a solid, punching a caliber sized hole and often passing straight through. On game that means poor energy transfer and a long tracking job. Sierra says so themselves, and so do we.

For hogs and deer use a bullet built to open at 1,000 feet per second: the 285gr fracturing subsonic sheds petals and dumps energy fast, and the 342gr Pork Shredder expands as one piece and penetrates deep. Our guide to the best 8.6 Blackout subsonic ammo for hunting compares them in the field.

300gr MatchKing against the other 8.6 loads

If you shoot a bolt gun and want the very best subsonic precision the caliber offers, look at the 300gr Berger Hybrid bolt action load. For a gas gun, or for volume, the MatchKing bucket is the practical choice. The 20 round box of the same round is there if you want to try it first.

Suppressor tuning with a match load

Fitting a suppressor changes barrel harmonics and adds weight at the muzzle, so point of impact shifts, usually by an inch or two at 100 yards. Measuring that shift accurately needs a round that groups well, and a 300 grain MatchKing does. Shoot a five round group without the can, five with it, and record the offset. NIOSH data on impulse noise makes clear why suppressed subsonic shooting is the hearing safe way to practise.

This load is gentle on a suppressor. Low pressure means low heat and light carbon, so a can rated for 308 Winchester handles it without complaint. Our subsonic ammo and suppressor category lists compatible cans, and the 8.6 versus 300 Blackout article explains why the larger bore is worth having.

Rifle, barrel and twist

The 8.6 Blackout 300gr Sierra MatchKing load needs the standard 1:3 twist. Nothing slower will stabilise a bullet this long. It is loaded for 8, 12 and 16 inch barrels and runs in AR10 pattern gas guns and bolt actions on a 308 bolt face. See our twist rate guide, 8.6 Blackout barrels and complete rifles if you are still building the host.

Shooting groups with the 8.6 Blackout 300gr Sierra MatchKing load

A match load deserves a proper test. Let the barrel cool between five round strings, shoot from a bipod or bags at a measured 100 yards, and record each group rather than remembering the best one. The 8.6 Blackout 300gr Sierra MatchKing bullet will tell you what the rifle is capable of; most factory 1:3 barrels print between 1 and 1.5 inches with it, and a good custom barrel will do better.

If groups open up, look at the rifle before the ammunition. A loose suppressor mount, a scope base that has worked loose under the recoil of a heavy subsonic, or a barrel nut torqued short of spec are the usual culprits. Because the 8.6 Blackout 300gr Sierra MatchKing round is so consistent, it makes those problems visible in a way a cheaper subsonic never would.

Keep a log. Barrel, suppressor, temperature, zero distance and group size, session by session. Over a bucket of 8.6 Blackout 300gr Sierra MatchKing rounds that log becomes the most useful document you own about the rifle, and it tells you exactly when a barrel or a mount needs attention.

There is one more reason the 8.6 Blackout 300gr Sierra MatchKing bucket earns its place on a serious shooter’s shelf: it lets you separate the rifle’s accuracy from the ammunition’s. Once you have a documented 100 yard group with this load, every other 8.6 Blackout round you test can be judged against it.

A hunting load that shoots 2 inches where the 8.6 Blackout 300gr Sierra MatchKing shoots 1 inch is still an excellent hunting load. One that shoots 4 inches is telling you something about seating, crimp or twist, and you would never know without a 8.6 Blackout 300gr Sierra MatchKing baseline to compare against. The bucket makes that baseline cheap enough to refresh every season, and 80 rounds of 8.6 Blackout 300gr Sierra MatchKing ammunition is enough to run a full comparison across three or four loads in an afternoon.

Shipping, tax and age

Ships to your home address in all 50 states. No tax stamp, no NFA paperwork, no dealer transfer and no tax added at checkout. Orders over $300 ship free. Ammunition is not an NFA item, so there is no dealer transfer or waiting period. Under federal law at 18 U.S.C. 922 no federal licence is needed to buy or possess ammunition. You must be 21 or older to purchase rifle ammunition, and an adult must sign for the parcel. Ammunition travels by ground carrier as a limited quantity shipment under 49 CFR 173.63, so air shipping is never offered.

Details are on the shipping and delivery page and in the FAQ. Ammunition cannot be returned once shipped, see the returns policy for damaged deliveries. The bucket weighs about 7 pounds packed and ships in one carton.

Every load we sell is manufactured to the pressure and dimensional standards published by SAAMI. If a match grade subsonic at bucket pricing is what your 8.6 needs, this is the one to order.

Frequently asked questions

Is the 8.6 Blackout 300gr Sierra MatchKing load for hunting?

No. Sierra builds the MatchKing for accuracy, with a thin jacket and a hollow point that is not designed to expand reliably in game. Use it for zeroing, group testing, suppressor tuning and match shooting. For hunting, choose the 285gr fracturing or 342gr Pork Shredder loads.

How is the 8.6 Blackout 300gr Sierra MatchKing bucket packed?

Eighty loose rounds in a resealable plastic bucket with a lid. It is the most economical way to buy this load and the bucket doubles as a range box.

What velocity does it run?

About 1,010 feet per second from a 12 inch barrel and 1,030 from a 16 inch, which keeps it subsonic in almost all conditions. On a freezing morning with a 16 inch barrel it can approach the sound barrier, so listen for a crack and step down barrel length if you hear one.

What is the ballistic coefficient?

The 8.6 Blackout 300gr Sierra MatchKing carries a G1 ballistic coefficient of about 0.750, which is exceptional for a subsonic load and the reason it drifts so little in wind compared with lighter bullets.

Can it ship to my house?

Yes. Ships to your home address in all 50 states. No tax stamp, no NFA paperwork, no dealer transfer and no tax added at checkout. Orders over $300 ship free.

Do I pay a tax stamp on ammunition?

No. Tax stamps apply to suppressors and other NFA items. Ammunition has no stamp, no Form 4, no waiting period, and we add no tax at checkout.

What twist rate does the 8.6 Blackout 300gr Sierra MatchKing load need?

1:3, the standard 8.6 Blackout twist. It stabilises the long 300 grain bullet and is what the load was developed around. Barrels of 8, 12 and 16 inches all work.

Can I return ammunition?

Ammunition cannot be returned once shipped. If you are unsure whether the load suits your rifle, start with the 20 round box of the same round and move to the bucket once you are happy.

You must be 21 or older to purchase rifle ammunition. Always use the correct ammunition in a firearm in good working condition. It is the buyer’s responsibility to know and comply with federal, state and local laws regarding the purchase and possession of ammunition.