300BlkTalk

I am looking to buy 16" 300 blackout barrel for an extra upper that I have. I am leery about the headspace issue, I am going to use an unused bolt and carrier so It might be ok as far as the headspace is concerned. Does any one make/sell a gauge for the 300 blackout. Would a 5.56 headspace work? the spacing should be the same with either a 300blk or 5.56 round as the distance from the bolt face to the chamber end should be the same.
If I am wrong please let me know where I am making a wrong assumption. I won't be offended if I am incorrect.

JA

Any in-spec 5.56mm bolt will headspace correctly with any in-spec 300 AAC Blackout barrel.

It is best to check, and you can use 300 BLK or 221 Fireball gauges, available from MidwayUSA.

If both are made right the headspace will be correct, but it is best to check.

You cannot use 5.56 or 223 REM gauges, the headspace is different for the 300 BLK.

Is there a difference between a 300 blk go guage vs a 221 Fireball? The reason I ask is because I have two 300/211 barrels. One an AR and the other a Savage 110. I already have a 300/221 chamber reamer. Can I just take a little more off with the reamer or do I need a 300 BLK reamer?

I've not tried any 300 BLK subsonics through either, just want to be safe. I also have 300/221 dies. Will I need to re-invest in another set of dies? Thanks for any and all help.

jfk wrote:Is there a difference between a 300 blk go guage vs a 221 Fireball?

No.

jfk wrote:I already have a 300/221 chamber reamer. Can I just take a little more off with the reamer

No. You need a 300 BLK reamer for 300 BLK.

300Blk wrote:

jfk wrote:Is there a difference between a 300 blk go guage vs a 221 Fireball?

No.

jfk wrote:I already have a 300/221 chamber reamer. Can I just take a little more off with the reamer

No. You need a 300 BLK reamer for 300 BLK.

Thank you Robert. Any idea if my existing dies would work?

Redding 300/221 dies work.