COAL 300 AAC question

[tsubaki]

I was impressed enough with the little information I could find on a bullet to reload for the 300 Blackout that I bought a box of them to try, but I need some help.

The bullet is a Sierra #2124 135gr HP.

I manipulated a case enough to be able to insert and remove a bullet and still chamber but holding the bullet firmly.

I then dropped a bullet into the chamber, inserted the case and pressed it forward with a dowel.
After doing this several times I kept arriving at an overall length of 2.152". This is contacting the rifling.

Case length is 1.360".
Bullet length is .900".
Only .108" of bullet is in the case neck.

In order to get a reasonable amount of bullet into the neck I arrived at an arbitrary COAL of 2.080".
This is .180" of bullet in the case and .072" off the rifling.
A Lee factory crimp die will be used.

Other than contacting Sierra (where's the fun in that?), anyone have any suggestions or comments?


I've not yet arrived at a charge rate for this bullet but am guessing something around 13.5gr to 14.5gr of 2400 might be reasonable.
In my 16" barrel I was hoping for close to 2000fps with this bullet but I don't believe 2400 will safely do it.
One more powder type on the shelf is likely.

[SafetyJoe]

15.1 grains is the maximum I would use because that's what quickload says is the most you can do with that powder and still stay in the yellow pressure zone.
266

It says your velocity would be 2018 fps

[SafetyJoe]

13.5 grains would look like this so you're right in thinking that's a good starting load.
267

It says 1854 fps would be the velocity.

[SafetyJoe]

18 grains of lilgun powder would get you 2100 fps, but that's using 19% more powder than 2400

269

[tsubaki]

Thank you very much Joe.
Those answered questions I had not yet thought to ask!

[Mbaker78]

I've been wanting to try this same bullet out, let me know how they do.

[tsubaki]

Shot some with 14.5gr of 2400 this afternoon, testing only for function and velocity.
All did fine, average velocity 1866fps.

[tsubaki]

I'm finding Hodgdon's CFE-BLK interesting. Data available for 110gr to 230gr.
Max load with the Sierra 135gr is listed as a compressed 22.5gr 2090fps charge but only at 37,000 PSI pressure.

I've looked in my tri county area and no one has it yet but there is a gun show this weekend. I may look and see if some shows up before paying a hazmat fee or considering another powder. Still up in the air as to the powder type but 2400 don't appear to be getting it.

Ordered a couple of scopes for the AR's in order to see what the grouping does after I get the velocity where I can live with it.

[tsubaki]

So much for trying the CFE-BLK, none to be had.
Gonna try some AA1680.

[WarEagleEd]

Good luck finding it. I can't find any locally.

[tsubaki]

So,
20.0gr of AA1680 averaged 1940fps with the 135gr HP.
Groups were a little less than 1" at 50 yards.