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Can someone explain why a person would want a small diameter bullet at subsonic velocities when you could get better energy and out of a larger diameter bullet of the same or more weight moving at the same subsonic velocity?

Example, the .300 BO or 6.8 with a 225 gr bullet at subsonic velocity vs something like the .338 Spectre with a 225 gr bullet or even a .45 ACP (or .460 Roland) with a 230 gr bullet.

I understand the desire for firing suppressed and can see where this is better with subsonic loads but do not understand using heavy for caliber bullets such as the .30 calibers and the 6.8.
 

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I have read a lot about most of them and now have no interest in any that are sub .338 caliber. The 300BO to me seams like a a waste of good components I had seriously considered a dedicated 30 cal subsonic rifle but in 308win using 220-240 grain OTM bullets. The 458 SOCOM was and still is a very interesting caliber to me but don't like the idea of limited availability of ammo and brass, high cost of quality components and the modifications needed to the receivers not to mention a suppressor that wouldn't be very useful for multiple calipers. I keep coming back to the 338 SPECTRE when I feel the itch to look into subsonic.
Not trying to stir up crap but I occasionally like to read through the 300BO pissing matches on other forums mainly when someone brings up 100 yard accuracy or ineffectiveness on game.
Just my 2 cents.
 

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Balistic coefficient . The smaller frontal area makes for lower velocity losses and higher impact velocity with more energy on target. Mechanically that's it .

At 50 yd it doesn't matter, at 200 the the best sub 45 cal at 230 gr is about equal to a 38 special +p at the muzzle. The BO holds up closer to 357 muzzle energy. I have no idea where the 26,27,28 cal come in but I expect that they are 50-60 ftlb or so higher.

The scale up in caliber generally speaking results in higher BC and obviously heavier bullets so much more energy. Lb for lb at the muzzle smaller calibers will hold energy better but we can't get a 750 gr 277 to make a direct comparison to a 750 gr 50 cal with a 1.0 (or more) BC ,but a 200-250 gr 45 will never get much over a .25 BC while almost any 200 gr 30 caliber is often in the in the .450-.500 BC a 27 caliber should get into the mid to upper .600s.

There can also be the recoil draw a 500 gr 45 will have 900 ftlb of muzzle energy (probably much more) and that has the equal effect on the other end. The 27-30 cal is more like 600# and as a result 2/3 of the recoil ,in equal rifles less. It is all a trade off, to get to a terminal number .
 

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You also have to take into account the weapon being used, and the size of the cartridge. It takes a certain amount of powder to achieve a velocity that can make use of the heavy for caliber bullets and push them fast enough to be practical. For really close range, I'd much rather have a suppressed .45 ACP than rifle. But for room to room clearing where I might encounter barriers, I'd want a short rifle like a .277 Wolverine with suppressor ammo. That would also work out to 75 yds or so if need be. The .300 BO isn't even on my radar. In my opinion, above a .277 caliber, you have to increase bullet weight too much to get the needed energy, and that cuts down on powder space in an AR. The subsonic Wolverine is a good balance between velocity, BC, and bullet weight.
 

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I have a Bison Armory 11.5" 6.8 SPC II barrel in their BSP format (Bison Sunsonic Platform.) The gist is it is a fast twist barrel that wil adequately stabilize a 200gr bullet at subsonic MV to clear a suppressor, as well as shoot standard supersonic 6.8 ammo. Bison says the subsonics will cycle the action, so long as a suppressor is mounted. ( Adjustable gas block recommended and installed in case it takes some adjustment.)

I bought the barrel because it was recommended to me and I couldn't find an ARP 12.5" barrel. I had Bison build a complete upper. Looks great and they seem to have done a very nice job. I'm waiting for my stamp, so haven't shot it yet.

I am hoping the POI with the subsonics is close to the POI with the supersonics at close range. If so I can see chambering a subsonic for a first shot, maybe the top round in the magazine too, for close ear or neck shots on stalked hogs or called coyotes or foxes.

Apparently the 200 grainer is barely stable at the muzzle and by 100yds is yawning enough to make visibly oblong holes in paper, so hopefully it will quickly tumble in flesh to make up for a lack of expansion.

FWIW, I don't see BC having much or anything to add to the smaller subsonic options, to include the 300BLK (a cartridge I have a hard time finding a niche for, and a hard time understanding others fanaticism about, especially when it's supersonic performance pales in so many ways compared to most options.) I don't see any rifle shooting subsonic to be anything other than a short range option. So, IMO, BC doesn't come into play.

I do see versatility as a reason to want a rifle that will shoot subsonic and supersonic.

ETA: Since MV is fixed to keep any bullet subsonic, the only way to increase energy is to increase bullet weight. Then the bullet length vs. twist issue rears its head both wrt to being able to shoot supersonic loads and being able to adequately stabilize the inevitably longer heavier bullets. So, at close range, larger diameter cartridges with rifles with adequate twist rates are going to have an edge over smaller bores. And the smaller bores will eventually overtake the larger bores because of BC (so long as they maintain adequate stability to fly pointy end first) but by then it is supersonic time, IMO.

JPK
 

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Can someone explain why a person would want a small diameter bullet at subsonic velocities when you could get better energy and out of a larger diameter bullet of the same or more weight moving at the same subsonic velocity?

Example, the .300 BO or 6.8 with a 225 gr bullet at subsonic velocity vs something like the .338 Spectre with a 225 gr bullet or even a .45 ACP (or .460 Roland) with a 230 gr bullet.

I understand the desire for firing suppressed and can see where this is better with subsonic loads but do not understand using heavy for caliber bullets such as the .30 calibers and the 6.8.
Smaller diameter with similar mass/velocity=deeper penetration for one, but that's not it. Simplest: the 6.8 has the versatility to do subsonic. But equally importantly, since pigs, deer and other desirable target critters like it quiet, and the only suppressed rifle I have is a 6.8, it's just fact that after a while buying gear gets to be just absolutely out of hand, even if you have an extra house to store it all in laying around. And suppressors are kind of a pain in the ass to acquire but once you get one, you wanna use it and get your effort's worth. There're a couple reasons. I'm gonna super, I'm gonna sub. I'm gonna hyper and see the reactions of game close and down range. I'm gonna punch paper, too. I'm done on buying gear. For at least a week or two.
Oh, yeah. It might be fun, too. More the merrier, EQ 2! Godspeed.
 
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