30 arx

[explorecaves]

6.5 Grendel Necked to .30 Caliber Beats 300 BLK

http://bulletin.accurateshooter.com/2013/12/new-30-arx-6-5-grendel-necked-to-30-caliber-beats-300-blk/

30 ARX Loads
H4198, CCI BR4 Primers,
Necked-up Lapua 6.5 Grendel Brass:
2419 FPS: 28.0 gr. H4198, Nosler 125gr Ballistic Tip Hunting Bullet (2.260″ OAL)
2517 FPS: 29.0 gr. H4198, Nosler 125gr Ballistic Tip Hunting Bullet (2.260″ OAL)
2363 FPS: 28.0 gr. H4198, Sierra 150gr BT Hunting Bullet (2.240″ OAL)
2441 FPS: 29.0 gr. H4198, Sierra 150gr BT Hunting Bullet (2.240″ OAL)

With its 57% greater capacity than a 300 Blackout, the 30 ARX is a more versatile, more powerful hunting cartridge (at least when loaded to supersonic speeds). With 150gr bullets running in the 2500 fps range, the 30 ARX offers impressive knockdown power in a cartridge that fits an AR-15 magazine.

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Looks to be a better option to the 300BLK but still falls short of the 6.5 Grendel...

[CrabbyMcNab]

I'm amazed at the versatility of free thinking individuals.

[hm2 clark]

Hmm.. If the 30 arx uses modified Grendel brass to use regular AR magazines and hold 38 gr of H2O then why cant we use that modified brass so our Grendels can use AR magazines and more powder too? We could call it a 6.6 arx.

[BjornF16]

Interesting...I wonder what is the performance from 10" barrel?

[Drifter]

Hmm.. If the 30 arx uses modified Grendel brass to use regular AR magazines and hold 38 gr of H2O then why cant we use that modified brass so our Grendels can use AR magazines and more powder too? We could call it a 6.6 arx.

I'm guessing that it has more capacity (vs 6.5 Grendel) because of the larger .30-caliber neck. I'm also guessing that they're using the term "AR-15 magazine" somewhat loosely, with reality being Grendel mags in a standard AR-15 lower.

[Klem]

6.5 Grendel Necked to .30 Caliber Beats 300 BLK

http://bulletin.accurateshooter.com/2013/12/new-30-arx-6-5-grendel-necked-to-30-caliber-beats-300-blk/

Looks to be a better option to the 300BLK but still falls short of the 6.5 Grendel...

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'.

[XcountryRider]

Silly question would this not fire from a 7.62X39 AR?

[VASCAR2]

Silly question would this not fire from a 7.62X39 AR?

Entirely different case taper, 7.62 X 39 requires a magazine with greater curve compared to the 6.5 Grendel mags because the 6.5 G has less case taper. The ARX has very little case taper and might feed out of an AR-15 mag with different follower and may or may not function with the ribs in the side of the 5.56/223 mag.

[AmishEskimoNinja]

I wonder if 30 ARX is more or less likely to break its bolt lugz than the Grendel...

[BjornF16]

What about 30ARX performance from a 10" barrel?...will it cycle subsonic? What MV for 125 grain supersonic?

[XcountryRider]

What about 30ARX performance from a 10" barrel?...will it cycle subsonic? What MV for 125 grain supersonic?

20in barrel gets over 2500fps with 125gr Nosler BT.

[KentuckyBuddha]

The raison d'etre for the 300blk was not just subsonic and 7.62x39 analog supersonic performance. It was also that you use pills from the .308, brass from the .223, and use the same bolt and mags from the .223. A person can get better performance from many different changes, but the ease of scaling/finding reloading supplies is unlikely to be apples to apples in these compare and contrast threads.

[Nukes]

I wonder if 30 ARX is more or less likely to break its bolt lugz than the Grendel...

Yes, the make or break question (pun intended).

[NugginFutz]

Based on the numbers gleaned from the Robert Whitely's post on AccurateShooter, I'd say the 30 ARX is about as likely (or unlikely) as a Grendel might be.

2419 FPS: 28.0 gr. H4198, Nosler 125gr Ballistic Tip Hunting Bullet (2.260″ OAL)
2517 FPS: 29.0 gr. H4198, Nosler 125gr Ballistic Tip Hunting Bullet (2.260″ OAL)
2363 FPS: 28.0 gr. H4198, Sierra 150gr BT Hunting Bullet (2.240″ OAL)
2441 FPS: 29.0 gr. H4198, Sierra 150gr BT Hunting Bullet (2.240″ OAL)

Charges and bullet weights are comparable, so I'd guess they would have very similar bolt thrust forces.

[Klem]

20in barrel gets over 2500fps with 125gr Nosler BT.

If we are still comparing against the Blackout you wonder why no Blackout barrels are produced longer than 16" by any manufacturer. A longer barrel gets you more velocity, but at the expense of having to tame subsonic rds below the speed of sound. It is likely the dwell time for your longer barrel will force you to push the gas block out further which is counter-productive in an under-gassed system like a 30cal barrel. The larger diameter barrel drops the cycling pressure a lot quicker than 6.5 and .223. Current wisdom is to bring the gas port in as close as possible which makes the idea of a barrel longer than 16" problematic.

If supersonic is all you want then cycling pressure and dwell time is a lot easier to manage, and then a more realistic comparison for the 30ARX is the Grendel, not the Blackout.