That Didn’t Go So Good: 300 Blackout Attempt

[spencerhenry]

I’d go so far as to say the 300bo is inherently INaccurate.

 

[dryhumor]

I have two 300 BO I shoot once and awhile. One bolt and one non ported side charger. A little time and effort and they both shoot reasonably well. I don’t shoot anything over 125 grain (as of now). H110 has been my go to powder. When I got some CFE BLK, I loaded a few to see how it worked. Results below from 160 yards. 4 shots per charge. I haven’t pursued this powder further.


I built a non ported side charger maybe 8-10 years ago. Gibbz upper and an Xcaliber barrel. It shoots factory bulk 125 grain pretty decent.



I have found Hornady 300 whisper cases work well. Federal is not very impressive. The rest are hit and miss. The bulk ammo pic above is decent. I found red box Winchester to be pretty warm, somewhat accurate. Other factory ammo is hit and miss depending on if the barrel likes it. For best results hand load.

 

[padom]

300 BO isn't an inherently accurate round

Haha. I've been told this for years....not true.. its all in the barrel. I went through 4 or 5 barrels till I found one thst actually shoots.

If this isn't accuracy I don't know what is. 7x5 @ 100yd with a 0.521" agg

10.5" Rainier Ultramatch SBR
Shot with bipod and rear bag from the bench with a Razor 5-25 for load development. Intended purpose was head shot accuracy from 100yd and in...once I saw how accurate it was, I put it's Leupold MR/T 1.5-5x20 CM-R2 back on it and tested this loads accuracy and consistency at distance even though I didn't build it for that. Went 5 out 5 on steel st 200M, 300M, 400M and the Ram at 500M. I'd say it's extremely accurate

Here the initial break in target with 125smk, first rounds down the barrel. Shot from top to bottom. After 30rd it really tightened up and stayed consistent.. the first 4 barrels shot like shit from all the top names you can think of...

 

[Sandstorm]

I'd say it's extremely accurate

My results concur with 125gr SST and 4227 in a 16 inch barrel.
It shoots real well.....but not unless you hand load for it.

 

[LVLAaron]

I didn't say it was impossible... just that it's not inherently accurate. I do find reloading for it tedious and annoying for some reason.

 

[Gargoyle]

From multiple parts or factory assembled upper?

Aero Precision parts, Ballistic Advantage barrel (BA makes barrels for Aero) torqued to specs. I've had great results so far with these parts. Like a hundred builds so far and all at least MOA. Most sub MOA. Let me get a bore scope down this tube and I'll report back.

 

[argrendel]

My first thought was barrel. Try a high end one before you give up. I’ve only shot one. My buddy’s Larue. Off hand, and suppressed! Man, was it fun!

 

[archerforkids]

Haha. I've been told this for years....not true.. its all in the barrel. I went through 4 or 5 barrels till I found one thst actually shoots.

If this isn't accuracy I don't know what is. 7x5 @ 100yd with a 0.521" agg

10.5" Rainier Ultramatch SBR
Shot with bipod and rear bag from the bench with a Razor 5-25 for load development. Intended purpose was head shot accuracy from 100yd and in...once I saw how accurate it was, I put it's Leupold MR/T 1.5-5x20 CM-R2 back on it and tested this loads accuracy and consistency at distance even though I didn't build it for that. Went 5 out 5 on steel st 200M, 300M, 400M and the Ram at 500M. I'd say it's extremely accurate

Here the initial break in target with 125smk, first rounds down the barrel. Shot from top to bottom. After 30rd it really tightened up and stayed consistent.. the first 4 barrels shot like shit from all the top names you can think of...

Second on the Ranier 10.5" barrel. Mine shoots way better than I do. I have hit steel consistently at 500 yards.

 

[David Milisock]

Aero Precision parts, Ballistic Advantage barrel (BA makes barrels for Aero) torqued to specs. I've had great results so far with these parts. Like a hundred builds so far and all at least MOA. Most sub MOA. Let me get a bore scope down this tube and I'll report back.

Being the weenie ass that I am I don't build any rifles, AR or not. I do research the calibers, sighting mechanism, triggers and may supply all the parts. I have a local guy 5 minutes away who has been doing most of my work for nearly 40 years. There are other guys I use around the U.S. for custom bolts and all have done a great job. The rifler did a custom 450 with my supplied parts and it's great.

I bought an Aero Precision complete upper, 16" Ballistic Advantage in 6MM ARC, at that time there were 2 grades I paid a bit more, I got an Aero lower. It shoots 1/2" at 100 yards. Hence the question about the build. ARs in my opinion are either matched bolt barrel sets or hit or miss.

My history was carrying an M2 Carbine in M1A1 configuration as my secondary. Obviously not a rifle with reach but my experience has been very good in close. I migrated to the CAR 15 and M4 no improvement in close but extended reach.

Now with the 6 ARC my carbine handles just as well as my old M2 in close but it makes 600+ yard hits with A2 iron sights. I waited 50 years for real improvements over the CAR 15. I'm leaning hard at another Aero Precision complete upper with a 20" minimum barrel. That finishes a field kit, in close and out past 1,000 yards with one projectile and a 15 second upper change.

With all this said I'm researching an AR for my grandson and 300 has been my cartridge consideration. I'll keep an eye on your progress as I was considering another premium grade complete Aero upper but if you make this one work I'll have your experience to gain from.

 

[dellet]

This should probably be my post for "Why I feel a disconnect with other shooters thread" I like the round.

It's not "inherently inaccurate", But it's definitely not 6.5 Creedmore off the shelf accurate.

The 300 Whisper, 300/221 and all the previous incantations never had the Inaccuracy reputation that the 300 Blackout seems to have gathered, What Changed?

What changed was the end user and the expectations of the shooter.

Ignore the cartridge and look at the platform and how it was pitched when it went SAAMI. It was pitched as a Military grade weapon capable of 2 MOA out to 450-500 yards with multiple barrel lengths 9-16". Capable of shooting suppressed or not, both sub and supersonic, with only a magazine change.

Essentially four different rifles, 12 if you consider barrel lengths, 18 if you want to talk gas system lengths, That need to operate with only two boxes of ammo. 120 grain supers, 220 grain subs. able to shoot full auto. Think about that for a moment.

Unleash that idea on the public as the latest and greatest Special Operator weapon that demands sub $400 dollar AR 15's and $6 a box blasting ammo.

To complicate matters, release the cartridge 6 months before an AR 15 building component and ammo/component shortage that makes the current one look like a joke.

Hard to believe it's been 10 years since Sandy Hook. Remember those folks as the anniversary approaches and keep an eye out for copy cats.

All that adds up to a whole bunch of new reloaders, whose side job is being an AR 15 armorer.

Any .308" bullet, with any powder you can lay your hands on will cycle and AR if you drill out the gas port to .125" in a pistol length gas system in a 16" barrel and then take all the weights out of the buffer if cutting spring coils doesn't work.

If it still doesn't work, or can't hold 1/4 MOA, using side mounted iron back up/operator type sights, blame the cartridge.

The flip side of that was a minority of folks that used quality components, with a tuned gas system. That also hand loaded their ammo.

Makes a big difference when you have 30 caliber feed ramps instead of 22. Or a gas system that doesn't cycle so hard and fast that bullets are set back .050" in the magazine or forward into the lands when chambering.

You want a 300 Blackout that shoots sub MOA?
Then treat the rifle and ammo that way. Think it out from the start.

You want to shoot subs and the occasional super, it's a completely different configuration than supers and the occasional sub. But only if you want to reach the accuracy potential of the cartridge.

I have tried probably no less than 30 different powders and easily over 150 different bullets over the years. Sadly some of the worst performers were labeled "specifically for 300 Blackout"