300 Blackout Subsonic accuracy a joke???

[RockyRiver]

You see everywhere people claiming 1" groups all day at 100 yards but I have not found a load that will come close. Searching online I've found no 10 shot group pics at 100 yards. Even with whole forums dedicated to 300 blk I found no solid data. I have no trouble getting it to group at 50 yards but it spreads way out past that. I've seen some good supersonic groups but I'd like to see AR based 300 blk subsonic testing. PLEASE POST HERE ONLY PICTURES OF 10 shot groups or five 5 shot groups with NO adjustments for fliers. I don't care what you heard, just show me on paper AT 100 YARDS please. Tell us what rifle and ammo and any other pertinant info.

Also, the title of this thread is just to get you to read it. I do believe there are accurate 300 blk subsonic setups out there, I would just like to see some on paper and know how they are setup and what ammo.

My setup is a LMT 10.5" 300 blackout in a MRP platform with AAC SDN-6 silencer. Ammo tried Hornady 300 whisper, Gemtech 300 blk, Handloads with 208 Amax bullet and various powders EXCEPT Accurate 1680 which I do not have but have heard good things about.
Thanks in advance.

I can post pictures of the targets when I get home I suppose (if I kept them, not certain I did) but here is the data that I previously posted in the Handloading section of five shot groups (no adjustment for fliers) shot at 100 yards in good conditions at 87F and relative calm winds.

Nosler CC 220g - CCI41 - RE7- 10.8 grains - 12 SD - 999 fps - 1.13 MOA
Nosler CC 220g - CCI41 - RE7- 11.0 grains - 10 SD - 1,015 fps - 1.14 MOA
Horn A-MAX 208g - CCI41 - RE7- 11.0 grains - 12 SD - 1,076 fps - 1.08 MOA

I am using the 9" AAC barrel (7.62-SDN suppressor). I could load up more I imagine and get some five shot groups at an inch I imagine. I loaded these on my XL 650.

What was the COAL on the 208 A-max loads? Thats 1680 right?

[RDA]

Thanks Silent But Deadly, that is the kind of thing I would like to see. If you can find the pics please post them and I will keep M4Carbine updated the same as here with any new info. I have not tried Reloader 7 for powder yet. After I tryout the factory Silencerco and Black Hills loads I'll have to give it a try.

Here are two of the three I noted above, both are the Nosler Custom Competition:

[RDA]

What was the COAL on the 208 A-max loads? Thats 1680 right?

2.200" on the COAL for the A-MAX 208g (as well as the Nosler Custom Competion). No, it is Reloader 7.

Here are more results which includes some 1680:

viewtopic.php?f=141&t=94674#p907708

[dbooksta]

Searching online I've found no 10 shot group pics at 100 yards.

Subsonic long-range accuracy is difficult.

Here is one of my threads including a 20-shot 100-yard group.

And here's a 60-shot group with even more analysis.

[Dr.Phil]

To the OP,

I was working on my buddies LMT MRP this weekend trying to wrap my head around his accuracy concerns.
One thing I kept coming back to was that accuracy with the MRP was less than optimal with pretty much every barrel he has for it.
This brought me back to one of my original suspects for his issues.
The upper itself...
(It is the only common denominator.)

So, it occurred to me that the heart of the LMT system is its "Quick Change" barrel system.
Then I remembered that one of the things that AR accuracy buffs will often do is true the face of the upper so that there is a perfect fit to the barrel extension.
The LMT MRP is unlike a standard AR in the way that it retains the barrel.
There is zero force pushing the barrel extension into the upper receiver.
Only two locking pins.
One pin located the barrel assembly and the other tightens the "barrel pocket" to remove play.

The LMT MPR is not a custom built product.
It is mass produced and by its very nature, must have built in tolerances in order to accept different barrel assemblies.
These tolerances mean that there will be a less than perfect fit between the upper receiver and the shoulder of the barrel extension.
Any gap in this critical area could account for lowered accuracy potential.

So, I was outside walking the dog and drinking a beer over the weekend.
This concept kept bouncing around inside my brain and I was trying to come up with a bedding solution that wouldn't permanently attach the barrel to the upper.
At this point in time, I looked down at my beer and had a light bulb moment.
Shims...

In order to test my bedding theory, there isn't any need to waste a bunch of time with epoxies and release agent.
I just needed to use an empty beer can and fabricate some shims.
So, I cut apart said beer can, carefully measured the dimensions of the barrel extension and proceeded to cut out a shim.
To make the difficult cuts in the aluminum, I used a high end math compass with pins on each end.
Then to make the cuts, I just kept turning the compass until it cut all the was through the material.

Anyhow, I installed the newly fabricated shim on the barrel assembly with the shiny side touching the barrel.
(That side of the can has the liner on it and would make it adhere.)
I reinstalled the barrel assembly and it was slightly tighter and required a slight tapping to get the indexing pin to align.
After I assembled and torqued everything, I noticed a familiar sound.
Every time I tapped the barrel, it now had a similar "tuning fork" sound, just like my precision bolt guns.

I'll do a new accuracy work up on this rifle this week. (Supersonic Only)
It will consist of back to back 5 shot groups at 100 yards to determine group size.
In order to give it every chance to shine, I will be using my personal lower receiver and will top the upper with my 25X Leupold FFP for the test.
If everything tests out, I may custom bed each of the barrels to the upper using JB Weld.

Anyhow, since your accuracy issues were also with the LMT MRP, I thought that I would let you know.
(FWIW, in my research it seems that 1 MOA accuracy with the LMT MRP is few and far between.)

[voip-1]

I think people have to be realistic in comparing accuracy when shooting paper targets to accuracy needed for combat effectiveness which for any combat oriented cartridge is the true benchmark for accuracy.

6 MOA at 100 yards would be considered operationally effective by the military community who would be using something like 300 BLK subsonic.

Punching perfect holes in paper targets at 100" is not something those guys are particularly worried about.

Similarly the cartridge might not be the best choice for hunting large game since the subsonic accuracy at those ranges will definitely not compete with cartridges geared more towards long range accuracy.

A good "practical" accuracy reference would be some of Nick Leghorn's videos of his AAC MPW 9" with AAC suppressor... he is free hand shooting steel plates at ranges of up to 200 yards and ringing the gong almost every time. That would be considered a good test of what the cartridge can do.

Just my .02.

[Meridian]

Punching perfect holes in paper targets at 100" is not something those guys are particularly worried about.

It had better be able to punch perfect holes at 100".

[superalpha]

Here are some groups at 50 yards using a red-dot with a 4MOA dot, AR with Wilson Combat barrel, "on TRGET" 208GR SUBSONIC:

I get similar results at 50yds with Hornady 300 Whisper 208gr AMAX and 9.5" AAC PDW upper, eotech unmagnified, unsuppressed. The 110gr VMAX is horrible and will cover a 5" area at 15yds. I don't know why...

[Kill By Number]

Dr. Phil,
My 5.56 12" barrel is very accurate as is my MWS .308 from LMT. That is why I was surprised to have trouble with 300 blk. I have actually been very impressed with the MRP system, it is my favorite AR and I own a gun shop and can choose pretty much whatever. I'm always interested in squeezing the most accuracy out of it though so let me know how your shim project works out!

[certifiable]

15 shot hand loaded subsonic group at 300 yards from a 9" sbr using iron sights