300 BLK Compatibility w/300-221 Question
 

I know the general answer is there is no definite answer because there has never been an official specification for 300-221 and a ton of different manufacturers have been cutting the chambers.

But, if I have a 300-221 chambered AR and I have a box of Remington 220gr 300 Blackout ammo, how would I go about determining whether it is safe to fire?

I noticed that the Remington 220gr ammo has an OAL of 2.089. That is shorter than my 220gr Matchking load (mine is 2.170) that works well, so I can assume I am safe there. Also their published safe powder type and load are well within the ranges that I've worked successfully with.

I don't actually have box of the ammo yet, so I can't try this yet. But assuming it chambers and extracts ok is there anything else I should check before firing a few rounds?

I see people saying the chamber is .004 larger in diameter than a whisper, so I'm guessing I could have an issue chambering the Blackout ammo.

I guess the question is that if the manufacturer can't answer the compatibility question, how can I determine it myself? We know some manufacturers (Shilen?) have cut chambers that turned out to be compatible with the Blackout before the Blackout was ever mentioned.

Any input/advice?

Where is it said to be 0.004 larger in diameter? Do you man the neck area?

Comparing 300 Whisper and 300 BLACKOUT chamber reamer prints I see the following differences:

Throat (lead) is .001" larger on the BLACKOUT
Throat is .0235" longer on the BLACKOUT
Breachface to shoulder is .0117" shorter on the BLACKOUT

The headspace is measured from the bolt face to a certain diameter on the shoulder and the headspace of 300 AAC BLACKOUT is the same as 221 Fireball, and the same as the CIP 300 Whisper(TM) standard (within 1/100 of 1 mm or so).

those aren't very big differences.

Just curious
 

I stopped in my favorite Gun store the other day. I asked a guy at the gun counter about the 300 blackout. He told me he had not seen anything in Remington's catalog about the caliber in ammunition or in production rifles. This is a gun store,,,,,not some clothing store like Bass Pro or Gander Mountain or Cabela. This store has thousands of firearms of every make, model, and caliber. Green Top is the name. They are located outside Richmond VA.

Like every year, he and a couple of the other guys are going to the Shot Show in Las Vegas next month. He promised to ask about the cartridge. He also said Remington was famous for coming out with 3-4 new wildcat cartridges a year that never really end up in production. He was a tad skeptical to say the least.

If Remington is serious about this cartridge, I would think they would be put the Blackout in a marketing campaign to their dealers and retailers along with whatever other new goodies they have coming out.

Anybody on this board call customer service at Remington and ask?

The Blackout is going to be one of the hot things at the Shot Show this year. I have talked to a number of the different AR manufacturers I shoot with at our super secret testing facility and all of them are working up a Blackout for the show. I may have some mock up suppressors on some of there guns as I am working on some integral suppressors for some of them. Everyone got caught with their pants down on this one. RSilver can correct me if I'm wrong but I bet Remington and AAC are waiting for SHot Show for the big reveal.

Thanks
 

Very good to know.

Rem 700 300 BLK
 

I called Remington about two weeks ago and asked if and when a Rem 700 in this cartridge would be available. The woman I spoke to said they are considering introducing one the middle of 2011.

We are just ramping up production before advertising it. Right now if there were a rush to buy guns and ammo, there would not be enough to meet demand. We will advertise it when we have a big ammo flow. By the end of February there should be over 1,000,000 rounds loaded.