Subsonic 300 Blackout question

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  • sbmike

    Ultimate Member
    Feb 19, 2011
    1,651
    Almost Heaven, WV
    I don't think MOA groups at 100 yards are possible with .300 BO subsonics, handloaded or not.

    I'm confused and curious. My friend and I were at the 200 yd. range at AGC this past Wednesday and there was a guy there shooting a suppressed rifle of some sort. It was as quiet as an air gun which is what made us notice (or not, as the case may be :)). When we went downrange to repost targets, he showed us a group of three shots that were definitely MOA with one barely MOA plus a flier that was about 2" away from the main group. We asked him what kind of rifle he was shooting and he told us it was an AAC Blackout with an AAC suppressor and hand loads. He also said he is a retired FBI firearms training instructor if that has any bearing on the discussion. I guess he could have been jerking our chain and had shot the grouping with another rifle, but he didn't impress either one of us as being a showoff or a blowhard and he wasn't selling anything. That's quite a jump from not likely MOA at 100 yds to MOA at 200 yds. Any thoughts? As I said at the beginning, I'm just curious is all. You certainly don't have to prove yourself given your excellent reputation but thought you might venture a guess.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    Why did you buy that rifle?

    It's more accurate to say I have one in my safe. My FIL likes Model 70's and Safari Grade Brownings. He bumped into a Browning in .458 that was very reasonably priced. Now he wants to sell it. When he wants to sell something, he gives me the job. It's a Belgian gun. Built in the 60's. Shot very little. No blue wear, a couple of very small dents in the wood. It had an older model Leupold scope, probably same era as the rifle.

    You want one?
     

    rsideout

    Senior Member
    MDS Supporter
    Dec 11, 2009
    6,711
    MD - Capital Region
    It's more accurate to say I have one in my safe. My FIL likes Model 70's and Safari Grade Brownings. He bumped into a Browning in .458 that was very reasonably priced. Now he wants to sell it. When he wants to sell something, he gives me the job. It's a Belgian gun. Built in the 60's. Shot very little. No blue wear, a couple of very small dents in the wood. It had an older model Leupold scope, probably same era as the rifle.

    You want one?

    If its integrally suppressed, sure.
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,247
    Mid-Merlind
    I'm confused and curious. My friend and I were at the 200 yd. range at AGC this past Wednesday and there was a guy there shooting a suppressed rifle of some sort. It was as quiet as an air gun which is what made us notice (or not, as the case may be :)). When we went downrange to repost targets, he showed us a group of three shots that were definitely MOA with one barely MOA plus a flier that was about 2" away from the main group. We asked him what kind of rifle he was shooting and he told us it was an AAC Blackout with an AAC suppressor and hand loads. He also said he is a retired FBI firearms training instructor if that has any bearing on the discussion. I guess he could have been jerking our chain and had shot the grouping with another rifle, but he didn't impress either one of us as being a showoff or a blowhard and he wasn't selling anything. That's quite a jump from not likely MOA at 100 yds to MOA at 200 yds. Any thoughts? As I said at the beginning, I'm just curious is all. You certainly don't have to prove yourself given your excellent reputation but thought you might venture a guess.
    The flyer you saw was not a "flyer", it was a bullet that left the group that the shooter would like to disregard. I'd suspect it is a symptom of a velocity excursion, and this is consistent with what I often see in the field.

    The reason I suggest that the subsonics are unlikely to deliver sub-MOA precision at 100 yards and beyond, AND the reason I asked the poster above specifically for his standard deviation numbers, then, failing to get any info, asked for his extreme spread (an easier number to arrive at), is that the standard deviation of every subsonic load I've ever had fired here has exceeded 5% of the average velocity. Remington subsonics are the worse I've ever seen for velocity control... they run almost 100 fps extreme spread, providing very tall groups at 100 and beyond.

    I have not yet seen anyone handload subsonic .300BO ammo that does any better than about 50 fps SD. Several shots may run about the same, but before the group is finished, we will have one run higher or lower and spread things out. I guess we could just call those lost bullets "flyers" and move on...or...we could be realistic.

    With a standard deviation of 5% or more (50fps at 1,000), sub-MOA at 100 yards is not possible. If we vary the muzzle velocity of a 220 SMK by 50 FPS, the difference in impact points is about an inch at 100 yards, so we are right at one MOA, even with a perfect rifle and perfect shooter, and it can only get worse.

    Flukes occur. If the person you encountered on the range really is able to consistently produce ammo with very low SD numbers that would support sub-MOA vertical spread and/or produce CONSISTENT sub-MOA groups ("consistent" means EVERY group is sub-MOA with no conveniently discarded shots) at even 100 yards, he would be a very special case and I know about 10 guys that would love to have his exact load recipe.

    FWIW, weighing all components is not really the key to consistent loads and we can weight sort by everything and weigh charges to 1/100th of a grain (LOL) and still see high deviation numbers if we are not in the right (OCW) place.

    I remain skeptical.
     

    Klunatic

    Ultimate Member
    Feb 28, 2011
    2,923
    Montgomery Cty
    The flyer you saw was not a "flyer", it was a bullet that left the group that the shooter would like to disregard. I'd suspect it is a symptom of a velocity excursion, and this is consistent with what I often see in the field.

    The reason I suggest that the subsonics are unlikely to deliver sub-MOA precision at 100 yards and beyond, AND the reason I asked the poster above specifically for his standard deviation numbers, then, failing to get any info, asked for his extreme spread (an easier number to arrive at), is that the standard deviation of every subsonic load I've ever had fired here has exceeded 5% of the average velocity. Remington subsonics are the worse I've ever seen for velocity control... they run almost 100 fps extreme spread, providing very tall groups at 100 and beyond.

    I have not yet seen anyone handload subsonic .300BO ammo that does any better than about 50 fps SD. Several shots may run about the same, but before the group is finished, we will have one run higher or lower and spread things out. I guess we could just call those lost bullets "flyers" and move on...or...we could be realistic.

    With a standard deviation of 5% or more (50fps at 1,000), sub-MOA at 100 yards is not possible. If we vary the muzzle velocity of a 220 SMK by 50 FPS, the difference in impact points is about an inch at 100 yards, so we are right at one MOA, even with a perfect rifle and perfect shooter, and it can only get worse.

    Flukes occur. If the person you encountered on the range really is able to consistently produce ammo with very low SD numbers that would support sub-MOA vertical spread and/or produce CONSISTENT sub-MOA groups ("consistent" means EVERY group is sub-MOA with no conveniently discarded shots) at even 100 yards, he would be a very special case and I know about 10 guys that would love to have his exact load recipe.

    FWIW, weighing all components is not really the key to consistent loads and we can weight sort by everything and weigh charges to 1/100th of a grain (LOL) and still see high deviation numbers if we are not in the right (OCW) place.

    I remain skeptical.

    Sorry for the delay in response I was on travel for a few weeks and just got back to the board today. I didn't chrono the rounds that day as I was pressed for time and just trying to sight in a new optic for an upcoming hunt. The load was 11.3 gr Accurate 1680 and Winchester small rifle primers. I have about 15 rounds left and will chrono them next time I hit the range to give you the SD.
     
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