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

The Blackout Ammunition .300 Blackout Subsonic 220gr Sierra MatchKing, 20 Round Box is stocked here. Below is the practical detail: what it is, what it fits and what you need to own it legally.

Specifications

Type	Sound suppressor
Bore class	.30 calibre
SKU	GA300220SMKSUB
Price	$36.99

What this changes

A suppressor reduces muzzle report by giving expanding gas somewhere to slow and cool before it leaves the muzzle. It does not make a rifle silent, and on supersonic ammunition it cannot remove the ballistic crack of the bullet itself. What it does deliver is a large reduction in the pressure wave at the shooter’s ear, less recoil, and the ability to hold a conversation on a firing line.

Calibre compatibility

This is a .30 calibre unit, which accepts .308 diameter and below. Never run a projectile larger than the rated bore. A baffle strike destroys the suppressor, can damage the host rifle and is genuinely dangerous.

Reading the specifications

Chasing decibel figures alone is a trap. Published numbers come from different test methods, and the difference you actually notice is between suppressed and unsuppressed, not between two good cans.

If you already own a mounting system, staying inside it is usually cheaper than starting a second one.

Price and what it buys

At $36.99 this sits at the affordable end of the category. That usually means simpler materials or a fixed mount rather than a compromise on function. Remember the 200 dollar tax stamp sits on top of the purchase price, and a mount may be extra.

Paperwork

Buying a suppressor is not like buying a rifle. It transfers under the NFA through a registered dealer, with an ATF Form 4, a 200 dollar tax stamp and a background check. Electronic filing has shortened waits considerably compared with paper. Suppressors are legal for civilian ownership in most states but prohibited in several, so confirm your own state before ordering. The regulator’s overview sits at the ATF.

Service and care

Maintenance depends on what you shoot. Pistol calibre cans accumulate lead and need periodic service, rifle cans usually do not. Never attempt to disassemble a sealed unit.

Related stock

Browse the suppressor range, 8.6 Blackout ammunition and 300 Blackout ammunition, or check what your setup delivers with the ballistics calculator.

How quiet is quiet

Suppression protects bystanders and dogs as much as the shooter, which is often the real reason hunters buy one.

Side effects worth knowing

Expect a period of relearning. Reduced blast and altered balance change how the rifle feels enough that early groups can be misleading.

Advice for first timers

If you have never bought an NFA item, start the conversation with a local dealer before you order. They will tell you exactly what they need from you.

What it is made of

Finish is more than cosmetic. High temperature coatings resist the heat cycling that strips ordinary finishes off a suppressor within a season.

Choosing well

Buy for the rifle you shoot most, not the rifle you might build. The versatile choice on paper is often the compromised one in the hand.

Frequently asked questions

Can I start the paperwork before it arrives?

The Form 4 is filed once the item is at your dealer, so the sequence is purchase, transfer to dealer, then paperwork.

Can I sell it later?

Yes, through another Form 4 transfer with its own tax stamp paid by the buyer.

Is this the current price?

Yes, $36.99 is current and this is held stock. Add the 200 dollar tax stamp when budgeting.

Does it change my point of impact?

Mounting a suppressor usually shifts point of impact somewhat. Confirm zero after fitting.

Can I shoot subsonic and supersonic through it?

Yes, within the bore rating. They will sound completely different, because supersonic ammunition keeps the bullet’s crack.

Will this change my zero?

Almost certainly, at least a little. Confirm zero with the can fitted before relying on it.

How hot does it get?

Hot enough to burn you and to cause visible mirage after sustained fire. Treat it as hot until proven otherwise.

Does it work with a muzzle brake?

Quick detach systems mount over a compatible device. Direct thread units replace it.

Can I use this on multiple rifles?

Yes, provided each host matches the bore rating and either the thread pitch or your chosen mounting system.