Accuracy of your SBR 300 Blackouts

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MisterHelix
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Re: Accuracy of your SBR 300 Blackouts

Post by MisterHelix » Sun Apr 16, 2017 8:30 am

Dellet, all that is likely true.

Shooting subs to 300 yards sounds fun, but it's also outside my personal parameters of accuracy requirements/work vs return.

I figure that for my uses (hunting and defense), the accuracy requirements for any load is about 2" out to the MPBR, assuming that the projectile will still perform at that velocity.

So, subs...I figure 75 yards with no come-ups, so 1.25" - 2" at 100 is fine.
Image

Supers, perhaps 150 yards max with no come-ups.
Image

Accuracy requirements flow from that, divided by the coefficient of lazy-ness.

I do load sub-MOA for my 308 bolt gun, but really it's academic I suppose. And as you alluded to, that rifle has a nightforce 4-14x56, and throws 168 amax's, so it's not really apples to apples.

I am interested in finding a short-cut powder that will meter well for subs, because hand trickling my training rounds is pretty inefficient.

(Edit)

So, I gave it another go with some magnification. Unfortunately that means I used a different rifle, and therefore a different barrel length.

Rifle:
16" AAC barrel
Trijicon ACOG TA31RCO-M150 (4x32)
Specwar 762
Geissele SSA
VLTOR A5H0 buffer
Image

The rifle is zeroed for suppressed supersonics (125TNT) at 100y.

Same 168 grain subsonic load, though obviously at a higher velocity. If it's hot out and I get the chamber hot, some go supersonic.

The good news is that the illuminated crossbar is exactly the right holdover for this load at 100 yards.

The bad news is that the group size worse, +/- 2" center to center, but it's not really a fair comparison, as it's a different barrel, different velocity, etc.

Worse yet, the POI is 3" left. I don't mind holdover/vertical drop, but the L/R offset is a deal breaker.

Image

Perhaps re-timing the mount to re-orient the suppressor could lessen this effect, or shift it more to the vertical plane, but it's my go-to supersonic rifle, and I don't really want to mess with it.

I like 300blk, both subs and supers, but in my experience, the premise of "switching from supers to subs with the change of a magazine" is somewhat overstated.

Though that's not really relevant to this discussion of overall accuracy.

What I ~can~ say with regards to SBR accuracy, is that with this particular load, MY 10.5" is more accurate than MY 16", given the advantage the 16" has with 4x magnification.

Now I might have to swap the optics and re-zero everything to satisfy my curiosity.

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dellet
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Re: Accuracy of your SBR 300 Blackouts

Post by dellet » Sun Apr 16, 2017 11:16 am

MisterHelix wrote:Dellet, all that is likely true.

Shooting subs to 300 yards sounds fun, but it's also outside my personal parameters of accuracy requirements/work vs return.

I figure that for my uses (hunting and defense), the accuracy requirements for any load is about 2" out to the MPBR, assuming that the projectile will still perform at that velocity.

So, subs...I figure 75 yards with no come-ups, so 1.25" - 2" at 100 is fine.
Image

Supers, perhaps 150 yards max with no come-ups.
Image

Accuracy requirements flow from that, divided by the coefficient of lazy-ness.

I do load sub-MOA for my 308 bolt gun, but really it's academic I suppose. And as you alluded to, that rifle has a nightforce 4-14x56, and throws 168 amax's, so it's not really apples to apples.

I am interested in finding a short-cut powder that will meter well for subs, because hand trickling my training rounds is pretty inefficient.

(Edit)

So, I gave it another go with some magnification. Unfortunately that means I used a different rifle, and therefore a different barrel length.

Rifle:
16" AAC barrel
Trijicon ACOG TA31RCO-M150 (4x32)
Specwar 762
Geissele SSA
VLTOR A5H0 buffer
Image

The rifle is zeroed for suppressed supersonics (125TNT) at 100y.

Same 168 grain subsonic load, though obviously at a higher velocity. If it's hot out and I get the chamber hot, some go supersonic.

The good news is that the illuminated crossbar is exactly the right holdover for this load at 100 yards.

The bad news is that the group size is about the same, +/- 1.5", but it's not really a fair comparison, as it's a different barrel, different velocity, etc.

Worse yet, the POI is 3" left. I don't mind holdover/vertical drop, but the L/R offset is a deal breaker.

Image

Perhaps re-timing the mount to re-orient the suppressor could lessen this effect, or shift it more to the vertical plane, but it's my go-to supersonic rifle, and I don't really want to mess with it.

I like 300blk, both subs and supers, but in my experience, the premise of "switching from supers to subs with the change of a magazine" is somewhat overstated.

Though that's not really relevant to this discussion of overall accuracy.

What I ~can~ say with regards to SBR accuracy, is that with this particular load, MY 10.5" is more accurate than MY 16", given the advantage the 16" has with 4x magnification.

Now I might have to swap the optics and re-zero everything to satisfy my curiosity.
What would bother me more is those holes don't look like the bullet was stable. If you were right at the edge of going super there's a lot of turbulence.

The whole just change magazine thing is a little over rated. It works well with something like an ACOG where you can set the scope for supers and more precise shots and then use it for close range subs as hit or miss both eyes open shooting. If you plug your loads into a calculator with drift you might find a happy medium where you could hold on the bridge of someone's nose and shot them in the left eye with a super and right eye with a sub.

As for powders that meter, there are quite a few ball powders that work well for subs. I have become a real fan of Vihtatuori. N105, N110, N120. They meter well, burn clean, and are quiet.

Certifiable has data posted in the load section of many powders in a very well laid out organized manner. Might be worth a look. I have data scattered from hell to breakfast.

Here's a better search function
https://cse.google.com/cse/publicurl?cx ... tl9hapdoi0

Once your work out some quirks I think your groups will probably be less frustrating.
300 Blackout, not just for sub-sonics.

MisterHelix
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Re: Accuracy of your SBR 300 Blackouts

Post by MisterHelix » Sun Apr 16, 2017 11:37 am

You know, that's true. I hadn't really thought about it, but those holes are kinda oblong. Perhaps that's contributing to the poor grouping from the 16".

I just went out back and put three rounds of my "standard" load (125tnt/[email protected]/cci450) through the 16" into the same target to confirm zero, and the holes were nice and round (and grouped right at 1" CTC).

I guess that 168 subsonic load isn't so great from that rifle. The holes from the 10.5" look pretty round, so that's good I guess.

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dellet
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Re: Accuracy of your SBR 300 Blackouts

Post by dellet » Sun Apr 16, 2017 11:43 am

MisterHelix wrote:You know, that's true. I hadn't really thought about it, but those holes are kinda oblong. Perhaps that's contributing to the poor grouping from the 16".

I just went out back and put three rounds of my "standard" load (125tnt/[email protected]/cci450) through the 16" into the same target to confirm zero, and the holes were nice and round (and grouped right at 1" CTC).

I guess that 168 subsonic load isn't so great from that rifle. The holes from the 10.5" look pretty round, so that's good I guess.
It seems I've read that 168's in general have problems with the 308 distance shooters with groups opening up and stability passing through the trans sonic speeds. Maybe slowing it down a little would help.
300 Blackout, not just for sub-sonics.

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GIGANTORE
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Re: Accuracy of your SBR 300 Blackouts

Post by GIGANTORE » Tue Aug 08, 2017 9:09 pm

Interesting thread. Makes me wonder what kind of accuracy is realistic with my 6.75" barrel and 8" long can.

19dsniper
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Re: Accuracy of your SBR 300 Blackouts

Post by 19dsniper » Tue Aug 22, 2017 3:04 pm

GIGANTORE wrote:Interesting thread. Makes me wonder what kind of accuracy is realistic with my 6.75" barrel and 8" long can.

That all depends on your barrel, load, and the person behind the trigger. If even 1 of those is off, the whole thing is down the toilet!
I have a 10.5 Noveske upper that i built. With 110 VMAX i have been able to get 0.36" 5 shot groups at 100 yards. That load averages 0.55" most of the time.
With that same upper, i have shot as small as 0.19" 5 shot groups at 100 yards with 110 Varmageddon projectiles (normal average is 0.42"). These are all hand loads and while using a 3.5-21x50 Bushnell elite DMR.
Image
Top Target is 110 Varmageddon, bottom target is 1 shot for CLEAN BORE (still have a habit of calling it cold bore) and then 5 more 110 VMax.)
I only use the scope during load development and then take it off to run my normal optics. I normally keep a Micro T1 on this one, sometime a 1-6x though.

I recently purchased a 7" upper because i was hoping to have a shorter "truck gun". The average of all of my groups with that upper was 5.38" with the largest being 7.44" and the smallest being 2.73" (not really, that was what it measured before i realized it was missing 3 rounds from the 10 round group).

That being said. This was not a barrel that was in the same league as a Noveske. I was really hoping for 2.5" or better with supers out of this upper. But needless to say, this upper went back and i will just save my money and be extremely happy with what i already have.

Even if you are a good shooter, meticulous reloader, have a good optic, great trigger, and all that stuff, it doesn't mean anything if you are missing even 1 piece of the puzzle.

Go out and shoot that 6.75 and get back to us! I'm dying to find out for myself because i really want a short barrel THAT SHOOTS! I would love to hear back and read a write up on how it does, any issues you may or may not have had, accuracy, reliability, etc.

Best of luck!

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GIGANTORE
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Re: Accuracy of your SBR 300 Blackouts

Post by GIGANTORE » Fri Aug 25, 2017 8:43 pm

19dsniper wrote:
GIGANTORE wrote:Interesting thread. Makes me wonder what kind of accuracy is realistic with my 6.75" barrel and 8" long can.

That all depends on your barrel, load, and the person behind the trigger. If even 1 of those is off, the whole thing is down the toilet!
I have a 10.5 Noveske upper that i built. With 110 VMAX i have been able to get 0.36" 5 shot groups at 100 yards. That load averages 0.55" most of the time.
With that same upper, i have shot as small as 0.19" 5 shot groups at 100 yards with 110 Varmageddon projectiles (normal average is 0.42"). These are all hand loads and while using a 3.5-21x50 Bushnell elite DMR.
Image
Top Target is 110 Varmageddon, bottom target is 1 shot for CLEAN BORE (still have a habit of calling it cold bore) and then 5 more 110 VMax.)
I only use the scope during load development and then take it off to run my normal optics. I normally keep a Micro T1 on this one, sometime a 1-6x though.

I recently purchased a 7" upper because i was hoping to have a shorter "truck gun". The average of all of my groups with that upper was 5.38" with the largest being 7.44" and the smallest being 2.73" (not really, that was what it measured before i realized it was missing 3 rounds from the 10 round group).

That being said. This was not a barrel that was in the same league as a Noveske. I was really hoping for 2.5" or better with supers out of this upper. But needless to say, this upper went back and i will just save my money and be extremely happy with what i already have.

Even if you are a good shooter, meticulous reloader, have a good optic, great trigger, and all that stuff, it doesn't mean anything if you are missing even 1 piece of the puzzle.

Go out and shoot that 6.75 and get back to us! I'm dying to find out for myself because i really want a short barrel THAT SHOOTS! I would love to hear back and read a write up on how it does, any issues you may or may not have had, accuracy, reliability, etc.

Best of luck!
Will do. Should be going to shoot this weekend

19dsniper
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Re: Accuracy of your SBR 300 Blackouts

Post by 19dsniper » Sat Aug 26, 2017 2:58 pm

I don't want to thread hijack but it still relates to the OP's topic. I just went yesterday and tried some different OAL measurements with the same loads. It shot like a shotgun with some of them. I may upload some pictures in the next few days with some additional data. But needless to say, the 2.100 OAL that i was running before is the way to go in MY rifle.

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