300BO flash hole

[milsurpshooter]

Still playing with my new upper in 300 BO,I am in the process of making the brass out of 223 Rem ,a very laborious job,my question is : according to C.E .Harris brass used for cast loads have to have the flash hole reamed to 0.099 size to prevent case shoulder set back.Am i safe to assume it is the same rule for the 300 BO?

[Tatume]

No. Unless you are going to shoot extremely light loads, leave the flash hole alone.

[6bg6ga]

I've made thousands of 300 blackout cases by simply putting them in my saw jig and cutting them off followed by inside and outside neck deburring and then running thru the sizing die. I've never enlarged the flash hole.

[Smoke4320]

Uniforming the flash hole will give you consistant ignition a good thing if you are into
Accuracy. Enlarging the hole in blackout is not needed

[Tatume]

We make the depth of the primer pocket uniform and de-burr the flash hole from the inside. Making the depth uniform puts all the legs of the anvil in contact with the case and is thought to improve primer ignition. De-burring allows the primer flame to disperse in all directions.

The hole itself is uniformly round already.

[milsurpshooter]

Thanks you all good info, on the same topic do you think is necessary to anneal the brass ?I have read that it is,but if it was not i would skip this fase wich is the one that is making the conversion so much more work.

[Tatume]

That depends. Are you using new, unfired 223 cases, or are you reforming once-fired cases? If the cases have been fired before, you should anneal. If new, they should already be annealed.

[milsurpshooter]

Ok ,will keep on annealing!