Do we have any information on the effect of a chamber "upgrade" from 300/221 to 300 BLK on accuracy with sub and supersonic loads yet?

So far there is no real information in this thread.

Thanks!

Mike

No you would have to get 10 300-221 barrels, shoot them all with 5 different bullets, 50 shots each, then convert them all, then repeat. A huge and expensive process.

I do have accuracy data for 300 AAC BLACKOUT 16" 1:8 twist with 110 grain Berger and Sierra bullets loaded to 2.1 OAL or less - 0.85 inches at 100 yards for 50 rounds (an average of ten 5-round groups).

http://img585.imageshack.us/img585/8...0rndgroupz.png

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I have a boltgun chambered in .300 Blackout with a PTG reamer. It is the most accurate 30 cal I have ever owned. the rifle barrel is a schillin blank thats was 1x8" wtist that is 16" long. Its dedicated to subsonics, the picture is a group of 11rounds total fired at 100yds. I had a called flier so I fired 11 instead of 10 rounds so the group would be 10 total. as best I can tell its .122" CTC .......
If your thinking of chambering to .300 blackout, do it! you wont be sorry.

With our 50 round test all shots were included in the 0.85 group at 100. No doubt one can find some really small 3 shot groups in there.

Well I think that the cartridge lends itself to being accurate due to the light recoil and High BC. of most the bullits used. I feel that this round aside from having many tactical uses is going to be a great round for up and comming shooters ( my Grandkids). I want to have a centerfire round for them that is deer capable but light recoilling...300 aac blk fills the bill nicely!:grin:

I agree that any of the 300 Whisper, 300/221, 300 BLK cartridges will fit the bill for the young shooter.

The question I posted was really aimed at the question ... "What price would I pay in accuracy for having my upper rechambered from 300/221 to 300 BLK?"

Must admit that is the cost for supersonic accuracy is too great, I would be hesitant to have the barrel rechambered.

No one knows in any sort of reliable way.

I really dont understand the problem? Its sorta like asking what is more accurate round "A" or round "B".... If you have a good barrel and reload you should be able to make loads for either that are accurate. My Blackout has a little more free bore than My whisper. I think that being a standard cartridge gives the edge to the Blackout! Good luck

I'd still like to know how you did this????? I can't get consistent groups less than 1.75" with any bullet under 130gr with a OAL in the 2.1" range using 1-8 or 1-10 twist bbls? Rechambered some of the bbls to 7.62x40 WT and they shoot 1" or less so it's hard to blame it on the bore or twist.

Haven't tried any Bergers, which bullet did you use?

Berger 110 and Sierra 110 Varminter. This was a test barrel, not an AR15. But it did have the 300 AAC BLACKOUT chamber.