300 blackout. Hornady data seems odd

[Phoenix]

In the hornady 9th edition for the 150gr interlock sp it shows the COAL as 2.220 I am going to use the 3031 plain base sp with cannelure. The COAL listed leaves the cannelure well outside the case. I have found other data where the COAL is 2.075 which puts the cannelure where your would normally see it. but the data is for h110 and lilgun, I am planning to use IMR 4227 since I could not find AA1680. .145 is a fairly significant case capacity reduction which concerns me about pressure spikes.

I am not used to seeing the manual list a COAL that leaves the cannelure .145 outside the case. Any insight is welcome. If you have loaded this or any of its sister bullets let me know what COAL and powder you used.

Thanks

[tomme boy]

Might have something to do with the profile of the bullet to make it feed in a AR magazine.

[Jupiter7]

I load the 150gr SST in 300blk. I load to the bottom of the cannelure, it is still completely out of case. I run them over 16grs lil gun with light crimp with FCD. This load chrono avg 1815fps in a 10" AR pistol, feeds and functions w/o issue. In a 16" barrel, I'd bet this is close to 2000fps. It'll print 1moa from a rest, freehand with scope in a AR pistol, 2+moa, but that's on me.

Edit to add: I also load the 3031 with same load and to bottom of cannelure, about the same results on paper, haven't chrono'd though. I picked these up from midways last blem sale.

[Phoenix]

Thanks for the response. I was just baffled by their published COAL. Now I have always varied the COAL for better accuracy but .145 is a big difference. I will just have to workup a load crimping at the base of the cannelure and watch carefully for pressure signs.

[Jupiter7]

You can expect slightly flattened primers in an AR. At least the 3 I've tried with this load. In my rem700 sps, slightly cratered pin strike but no flattening. I started my work up at 14.7grs. Lil Gun. I've seen flattened primers on tons of factory 5.56 fired from AR's, so i dont know how accurate of an indicator that really is.