300AAC chambers

[HeadedToTexas]

My first post at 300BlkTalk!

It's taking a while, but I am getting in to 300 Blackout. I have a Ruger American Ranch in 300BLK and just finished an AR build in 300BLK. My early loads were loaded with 150 grain FMJ, but my real mission is subsonic suppressed work, so I loaded up several hundred rounds with 245 grain HiTek coated lead from Missouri Bullet Company. The long bullets produced an initial COAL of 2.250".

They chambered without incident in the Ruger bolt gun, but the AR would not go in to battery until I set the bullets back to a COAL of 2.007". Works fine in both now and it makes me think I was just able to overcome the resistance of pressing the flattish nose of the bullet into the lands with the bolt gun, but not the spring and inertia world of the AR closing bolt.

Anyway, should not all 300AAC chambers be the same? Does that not include the shape of the lands? Thanks.

[excess650]

Bore and groove diameters vary by manufacturer, and then there is cut rifling, button rifling and hammer forged.....numbers of grooves vary, 5R, polygonal, etc.... All chambers are not cut by the same reamer, not all barrels are the same steel. Yes, there is going to be some variation in chambers. If your barrel isn't chrome lined or melonite, you might be able to run a throater in there to lengthen and/or enlarge the throat.

[HeadedToTexas]

It seems attractive to develop one load that will run in both guns, but not if accuracy suffers. Still some work to do.

[A-Game]

who made the barrel?

[TMD]

My first post at 300BlkTalk!

It's taking a while, but I am getting in to 300 Blackout. I have a Ruger American Ranch in 300BLK and just finished an AR build in 300BLK. My early loads were loaded with 150 grain FMJ, but my real mission is subsonic suppressed work, so I loaded up several hundred rounds with 245 grain HiTek coated lead from Missouri Bullet Company. The long bullets produced an initial COAL of 2.250".

They chambered without incident in the Ruger bolt gun, but the AR would not go in to battery until I set the bullets back to a COAL of 2.007". Works fine in both now and it makes me think I was just able to overcome the resistance of pressing the flattish nose of the bullet into the lands with the bolt gun, but not the spring and inertia world of the AR closing bolt.

Anyway, should not all 300AAC chambers be the same? Does that not include the shape of the lands? Thanks.

Did you test these loads first for velocity and stability? Also do you have a suppressor yet?

[HeadedToTexas]

Yikes! 2016? Between NFA jail and shopping months, it's been a long time. Finally got a Griffin Optimus.