Inconsistent subs in my 300 blk

[Beeron]

Greetings
I am having some issues getting consistent velocities in my 300 blk sub loads.

So far i have tried 175 gr hornady sub X and 180gr SST’s.

I typically get the first round if and test load shooting a fair bit faster than subsequent rounds which gives me large ES and SD values.

I have read that this may be a case fill issue.

So if i use heavier pills, i can compress smaller loads more consistently.

I have some 190gr copper monos on order which will be long and may help but does anyone have any experience to offer here?

Im using;
Ruger Ranch Gen II in 300 blk
Starline brass (virgin but fl sized and expanded using a .306 mandrel)
CCI 400 srp
Hodgdon CFE BLK

Thanks.

The gun shoots supers well.
110gr Barnes Tac TX shoot sub moa at 1965fps.

 

[4n2t0]

You might have better luck in the reloading subform.

 

[Bubba Yugga]

I had rough luck with CFE-BLK in loading 180gn 7.62x39 subs. Did way better with IMR 4198.
Also, try CCI 450 instead of 400. The greater brisance may compensate for the random lay of the loose powder and lower your ES.
Oh yeah, trim your flash hole too...

 

[homer76]

I shoot 210 and 245 grain cast bullets out of my 12.5 inch bolt action 300 Blackout using H110. Heavier bullets allow me to use a larger powder charge and seat bullet deeper to reduce the empty space in the casing. Cast bullets are are a lot cheaper.

I would suggest doing research on one of the many US forums as shooting subsonic 300 blackout is more common there than in Canada.

 

[porpoise]

On a burn chart cfe blk is slower than 4227 and close to reloader 7. I load subsonic in a few cartridges but not the blk I would not use a powder that slow its dirty and inefficient although the hodgdon site says its perfect for subs I find that hard to believe