Blackout Ammunition .300 Blackout Subsonic 220gr Sierra MatchKing, 20 Round Box

The Subsonic 220gr Sierra MatchKing 300 Blackout 20 round box is the classic quiet load for the cartridge at $36.99, about $1.85 a round. It is the box to buy when you want to zero a suppressed rifle, test a new can, or find out what all the fuss about subsonic 300 Blackout is about. Match grade, factory new brass, about 1,030 feet per second.

What the 20 round box is for

Twenty rounds is a zero and a group. It is the sensible first purchase of any new load, and for the Subsonic 220gr Sierra MatchKing it is also enough to measure how much your suppressor moves point of impact. Once you know the load suits the rifle, the 160 round bucket of the identical round costs less per shot.

Each box holds a plastic tray with 20 rounds, loaded in factory new brass with a match primer. The same lot control and final inspection apply as on every load we sell, and the round is gauged before it goes in the tray.

The 220 grain MatchKing

Sierra’s 220 grain .308 MatchKing is a boat tail hollow point built for accuracy. The jacket is thin and even, the core is weight matched and the hollow point is a manufacturing artefact, not an expansion feature. It became the standard subsonic 300 Blackout bullet because its length and mass fill the case capacity perfectly at 1,000 feet per second and because it groups as well as the barrel allows.

With a G1 ballistic coefficient around 0.62, it holds velocity well for a subsonic and drifts less in the wind than lighter bullets. It is the round most published 300 Blackout subsonic data is built on, and the one to start with if you own a suppressor.

Subsonic and suppressed: what changes

A supersonic bullet makes a crack as it breaks the sound barrier, and no suppressor can remove it. A subsonic bullet does not, so the only noise left is the muzzle report and the action. Put a can on the muzzle and the Subsonic 220gr Sierra MatchKing round is about as quiet as a centrefire rifle gets. Without a can the report is still a rifle report, only without the crack. the cartridge’s history explains why the cartridge was designed around exactly this pairing.

NIOSH puts the level at which impulse noise damages hearing at 140 decibels. A suppressed subsonic carbine is the one rifle configuration that gets close to safe without ear protection. Read subsonic versus supersonic 300 Blackout for the full comparison.

Box, bucket and the hunting loads

Option	Rounds	Price	Per round	Use
Subsonic 220gr Sierra MatchKing box (this listing)	20	$36.99	$1.85	Zeroing, testing, practice
220gr Sierra MatchKing bucket	160	$289.00	$1.81	Volume training
215gr Berger Hybrid Target box	20	$36.99	$1.85	Alternative match subsonic
205gr Punisher Series box	20	$48.99	$2.45	Hunting and defense

The 215gr Berger box is the other match subsonic at the same price and worth trying alongside this one. The 300 Blackout ammo range and the buckets category hold the rest, and our bulk guide explains how to plan a season’s supply.

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. Under federal law at 18 U.S.C. 922 no federal licence is needed to buy it. Buyers must be 21 or older for rifle ammunition and an adult must sign at delivery. Ammunition travels by ground carrier under the limited quantity rules in 49 CFR 173.63, never by air.

See the shipping and delivery page and the FAQ. Ammunition cannot be returned once shipped; the returns policy covers damaged deliveries. All loads meet SAAMI standards.

Start with a box of Subsonic 220gr Sierra MatchKing, learn what your suppressed rifle can do, and move to the bucket when you are ready.

Frequently asked questions

What is in the Subsonic 220gr Sierra MatchKing box?

Twenty rounds of 300 Blackout loaded with the 220 grain Sierra MatchKing boat tail hollow point in factory new brass, packed in a tray inside a retail box. Muzzle velocity is about 1,030 feet per second from a 16 inch barrel.

Is the Subsonic 220gr Sierra MatchKing round quiet without a suppressor?

Quieter than a supersonic, because there is no sonic crack, but the muzzle report is still that of a rifle. The load becomes genuinely quiet only with a suppressor fitted. It is designed for suppressed use.

Can I hunt with it?

No. MatchKing bullets are built for accuracy and are not designed to expand. Use the 205gr Punisher Series or the 196gr fracturing load for game and defense.

Why buy the Subsonic 220gr Sierra MatchKing box instead of the bucket?

To try the load before committing, to confirm zero, or because 20 rounds is all you need for a suppressor point of impact check. Once you know your rifle likes it, the 160 round bucket is about 20 percent cheaper per round.