Range Report  How important is BC below the sound barrier?

Nostradumbass

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Serious question, and I hope I’ve put this question in the right location.

I’ve purchased a full custom 300 AAC bolt gun that’s built for precision. The guy who had it built never shot it.

It has a 1 in 7 Shilen barrel at 16.5”

I plan to see what I can do with the rifle out to 600yds or so, using subsonic projectiles. “Obviously there are better long range caliber options. This is solely for fun.”

This leads to my question.... How important is BC at sub sonic speeds? I’ll be trying different match Bullets and loading, but would really like to see if anyone has had some experience with this application?

Thanks in advance!
 

Steel head

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    Serious question, and I hope I’ve put this question in the right location.

    I’ve purchased a full custom 300 AAC bolt gun that’s built for precision. The guy who had it built never shot it.

    It has a 1 in 7 Shilen barrel at 16.5”

    I plan to see what I can do with the rifle out to 600yds or so, using subsonic projectiles. “Obviously there are better long range caliber options. This is solely for fun.”

    This leads to my question.... How important is BC at sub sonic speeds? I’ll be trying different match Bullets and loading, but would really like to see if anyone has had some experience with this application?

    Thanks in advance!
    Everyday sniper and Berger had a really good talk about this.
    I think it was episode 5 or 6.
     
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    VargmatII

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    I had a blueprinted and rebarreled Remington 700 with 1:8 twist LW barrel in 300blk.
    I mostly shot 155 gran Scenar and ballistic tips at super sonic speeds and took it out to 440 meters. I shot 220 grain Scenar L och 208 grain A-max at subsonic speed and I can only say that it was rough keeping something that looked like accuracy up at 300 meters. I would say that trying to take it out to 600 is probably doable, but it probably will get old pretty fast as the hit ratio will be terrible.
     

    clcustom1911

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    I had a blueprinted and rebarreled Remington 700 with 1:8 twist LW barrel in 300blk.
    I mostly shot 155 gran Scenar and ballistic tips at super sonic speeds and took it out to 440 meters. I shot 220 grain Scenar L och 208 grain A-max at subsonic speed and I can only say that it was rough keeping something that looked like accuracy up at 300 meters. I would say that trying to take it out to 600 is probably doable, but it probably will get old pretty fast as the hit ratio will be terrible.
    Maybe your 208's were transonic from the muzzle and that's what was messing with your accuracy?
     

    Nostradumbass

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    I had a blueprinted and rebarreled Remington 700 with 1:8 twist LW barrel in 300blk.
    I mostly shot 155 gran Scenar and ballistic tips at super sonic speeds and took it out to 440 meters. I shot 220 grain Scenar L och 208 grain A-max at subsonic speed and I can only say that it was rough keeping something that looked like accuracy up at 300 meters. I would say that trying to take it out to 600 is probably doable, but it probably will get old pretty fast as the hit ratio will be terrible.

    Thanks.

    I have reached out to Berger, and will be trying a few of their hybrid projectiles. Their 245gn Elite Hunter is what I am hoping to be successful with. I should be able to get some actual range data next week. I will keep you informed on my results.
     
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    VargmatII

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    Thanks.

    I have reached out to Berger, and will be trying a few of their hybrid projectiles. Their 245gn Elite Hunter is what I am hoping to be successful with. I should be able to get some actual range data next week. I will keep you informed on my results.

    I will keep my eyes on this thread.
    What scope will you use? You will have to dial a lot of elevation on it to really reach out with the 300BLK.
     

    Nostradumbass

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    I will keep my eyes on this thread.
    What scope will you use? You will have to dial a lot of elevation on it to really reach out with the 300BLK.
    Yes sir! There is definitely a significant amount of elevation changes needed for distance with this loading.
    I’ll be using a Leupold Mark 6 3-18 with a Horus H59 reticle.
     

    db2000

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    Yes sir! There is definitely a significant amount of elevation changes needed for distance with this loading.
    I’ll be using a Leupold Mark 6 3-18 with a Horus H59 reticle.
    I think it’s fun too. I’ve only shot sub to 250 but I’ve got my EoTech EXPS3-4 reticle down on 8-12” steel @ 50-250 yds with Nosler 190 custom competition HPBT. 8” barrel Seekins gas gun. I like the long pause before the steel rings at that distance. Can’t imagine 600 😂
    FWIW an EoTech rep told me the 1st and 3rd dot on the EXPS3-4 equal the 1st and 2nd dot on the 300 blackout 2 dot reticle.
     
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    eastexsteve

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    I don't know if this helps you, but I have a PCC in 9mm with a 16" barrel. Just for grins, I once mounted a Nikon FX1000 on it, and sighted it in for 100 yds. Long story short, I found it to be much more accurate at distance with ammo that started out subsonic.
     
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    Centurion123

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    I had a blueprinted and rebarreled Remington 700 with 1:8 twist LW barrel in 300blk.
    I mostly shot 155 gran Scenar and ballistic tips at super sonic speeds and took it out to 440 meters. I shot 220 grain Scenar L och 208 grain A-max at subsonic speed and I can only say that it was rough keeping something that looked like accuracy up at 300 meters. I would say that trying to take it out to 600 is probably doable, but it probably will get old pretty fast as the hit ratio will be terrible.

    What kind of group size are we talking about at 300? Both those bullets have a G7 of about .324, how did this match with actual drop?
     

    VargmatII

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    What kind of group size are we talking about at 300? Both those bullets have a G7 of about .324, how did this match with actual drop?

    I had to go back and look at old notes and in a thread I did about the rifle/caliber back in 2015.
    Im sorry to say that I dont have any records of the accutal dope used, I will say from memory that 6-8" groups was hard to keep at 300 meters with the subsonics. And to my surprise the furthest I ever shot with the supersonic loads (155 grain scenar) was acctually 515 meters at a competition, I scored 3/6 hits at that stage.

    Heres what the rifle looked like before it was parted out and traded for another rebuilt R700 in 6.5x47 Lapua.

    1606843544146.png
     
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    Nostradumbass

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    I had to go back and look at old notes and in a thread I did about the rifle/caliber back in 2015.
    Im sorry to say that I dont have any records of the accutal dope used, I will say from memory that 6-8" groups was hard to keep at 300 meters with the subsonics. And to my surprise the furthest I ever shot with the supersonic loads (155 grain scenar) was acctually 515 meters at a competition, I scored 3/6 hits at that stage.

    Heres what the rifle looked like before it was parted out and traded for another rebuilt R700 in 6.5x47 Lapua.

    View attachment 7488410

    I’ve shot a 6.5x47 Lapua for the past 9 years, and absolutely love the cartridge.

    My 300 AAC is similar in to yours. 16” rem700, suppressor, but manners folding stock. I’m optimistic, but it will be what it be when the Bullets hit the paper. 🤙🏽
     

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    culater

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    Serious question, and I hope I’ve put this question in the right location.

    I’ve purchased a full custom 300 AAC bolt gun that’s built for precision. The guy who had it built never shot it.

    It has a 1 in 7 Shilen barrel at 16.5”

    I plan to see what I can do with the rifle out to 600yds or so, using subsonic projectiles. “Obviously there are better long range caliber options. This is solely for fun.”

    This leads to my question.... How important is BC at sub sonic speeds? I’ll be trying different match Bullets and loading, but would really like to see if anyone has had some experience with this application?

    Thanks in advance!
    Here was my journey to 800 yards


    I would suggest the 208 elds for you