30 arx

[NightForce]

It's not hard to compare the Blackout against any other supersonic cartridge and have it fail. The whole point of Blackout is so the shooter can engage both supersonic and subsonic with the one gun, and do this by nothing more than changing mags. To be a fair comparison you need to consider the 30ARX' subsonic ability.

Subsonic is the Blackout's 'raison d'etre' and its proponents put up with a pretty average supersonic ability to have this subsonic as well, to 'have their cake and eat it too'.

Lets compare the two subsonic (Quickload)...

Using heavy rounds; 220gr commercial and 240gr cast lead from a 16" barrel;

Same caliber so they are both stable when subsonic. (Pass).

Does the 30ARX cycle the action of an AR? You need over 4,500lbs at the gas port. Quickload is showing over 5,000lbs gas pressure at the carbine length gas system mark (7"), so yes it does. Manufacturers are now trending towards pistol length gas ports for the Blakcout for even more reliability. (Pass).

Case capacity. 38gr of capacity to fill to safe limits. Using any normal powder to obtain high subsonic and not exceed it (1050fps) the loads are coming in at under 50% filled. Under 80% and you risk Secondary Explosion Effect and Flash-Over. It will happen eventually. (Fail).

Perhaps if you used Trail Boss however my program does not list that. Trail Boss will fill more of the excess capacity but it all boils down to having the round no more than 1050fps with at least 5,000lbs at the gas port to cycle then it will work.

Trail Boss does not cycle an AR with heavy 200+gr projectiles in a Blackout. This means you have to crank the handle each time, and what is the tactical benefit of that?! It is much quieter however when using the lightest 110gn 30cal projies when comparing it with heavier cycling 220gr; both going subsonic. The guys on the Blackout forum call this 'Hollywood quiet'.

So, can the 30ARX be made to shoot subsonic and reliably cycle the action without creating a dangerous situation with under-filled cases? Using normal powders, no. There is a small possibility with Trail Boss powder however so until someone tries using the 30ARX cartridge we cannot say for sure. Having tinkered around with Blackout/Trail Boss/Subsonic for a couple of years now I doubt it. Likely you will make it safe but unlikely it will have enough grunt to cycle the action.

This being the case the 30ARX beats the Blackout supersonic, but fails subsonic. Neither one 'wins'.

I'm always amazed at how many try to compare a cartridge to the 300 Blackout WITHOUT understanding the 300 Blackout was designed to shoot both supersonic and subsonic......

Great post!!