.300 BLK subsonic vs. 10 mm subsonic

[Wreck-n-Crew]

One advantage to the Blackout is that if someone wanted more power and greater range and accuracy over a 10mm at a given moment it just requires a load change making it more versatile in a given role. Such as a quiet range gun to a less quiet more effective gun. To me that solves my conundrum. Plus i have a 309 225gr and 230 gr. mold.


But i do love my 10mm. Because who doesn't? They are cool. In an AR platform or PCC I've longed for. But not as much as i did. My pistol is not one where the mags will likely ever interchange like Glock mags in my Ruger PC. I would have to justify selling My Elite match 10mm or purchasing another 10mm Glock in order for me to get a 10mm PCC. Oh no...that's 2 guns...and i stop myself. Since i carry a 9mm...i just stick to the Ruger and the G19 and spend my money on another Savage heavy barrel target gun.

One more note worth thinking about is load. Although i believe it was mentioned already, a subsonic load must be subsonic in a longer barrel. So fast powder is a must to get function and prevent the increased velocity associated with many slower burning 10mm powders.

 

[pdsmith505]

Not to any usable degree. Even with a 6.5 bullet that has a superior BC to the .30 caliber, it doesn’t matter much subsonic.

Might be worth plugging in some numbers to see difference between the two and what setting a speed limit does to trajectory as well as get a better idea of what would be a “useable range” for each.

If we took the 123gn SMK and loaded it to 1050 FPS the first thing we do is take a hit in the BC, normally .510 over 1635fps but drops to .420 subsonic (not that it matters much going that slow).
https://www.sierrabullets.com/store/...mm-123-gr-HPBT

Anyhow zeroed at 100 we get

0 yd -1.5” 301 ft/lb energy
50 yd 3.4”
100 yd 0
150 yd -12.1
200 yd -33.5
300 yd -105.3 229 ft/lb energy

Keeping everything the same but using a .458”, 405 gn bullet with a .281 BC we get

0 yd -1.5 991 ft/lb energy
50 yd -3.5”
100 yd 0
150 yd -12.7”
200 yd 35.2”
300 yd -111.5” 674 ft/lb energy

So the big old bullet that has the BC of a brick doesn’t loose that much before trajectory gets almost unusable, with both loads. It is also worth noting that it has more than twice the energy at 300 yds than the lighter bullet has at the muzzle and over 3 times the energy upon exit.

Mathematically the better BC bullet will catch up and surpass the other, in energy, at some point but it will be beyond their usable range. At 2000 yards the lead for energy the 405 has over the slicker 123 is cut to just 63 ft/lbs but you are looking at 879.5 FEET of drop at that point...

Right, because the 405 gr bullet has nearly 4 times the momentum than the 125 gr bullet and will take longer to slow down. You are varying two factors and trying to draw a conclusion. Looking at a 200gr 40 caliber .40 cal vs a 200 gr .30 caliber and only varying the caliber/BC, as above, the shape of the bullet matters a lot.

I think that's the main attraction of a PCC. People will say that the conversion to 300 BLK is cheap but I'm wondering how many people actually switch their uppers everytime they want to shoot a different cartridge or even shoot subsonic. I'm also wondering if people consider that 300 BLK is 0.40/rd where 45 ACP ammo is about half that.

In my case, yes. I have one SBR'd AR lower that serves as a .300 blk, .22lr, and 9mm. Still planning on putting together a short 5.56 upper for it at some point. If every upper you have doesn't require a tax stamp, it makes more sense just to build a whole new rifle, since the lower can likely be built for less than the stamp.

Granted, I got into BLK to get around VA's caliber rules for deer cartridges.

I wasn't talking about loaded ammo, I was talking about the bullets themselves, good expanding .40 cal bullets are clearly much, much cheaper than expanding .30 cal heavies, and that's an advantage. I think most folks who are taking up subsonic suppressed projects probably reload, so component costs would be much more important than loaded ammo costs. .300 BLK is a pricey round for the performance you get, I think that's a worthy consideration if you are considering different options.

We'll see what the SUB-X bullets end up costing once you can buy them as components. I suspect they won't be any pricier than comparable hunting/defense bullets. Just found that Nosler provides a subsonic ballistic tip in 220 gr that runs $0.56/bullet from Midway (https://shop.nosler.com/nosler-bull...ting-30-caliber-220-grain-rn-bullet-50ct.html and https://www.midwayusa.com/product/6...r-308-diameter-220-grain-round-nose-box-of-50). Even though that is 2x the cost per bullet of defensive handgun bullets...

But if we are taking cost, .300 blk uses standard magazines, standard bolts, standard buffers, etc. All stuff that is cross compatible with 5.56. Just need a barrel.

A 10mm (or any pistol caliber AR setup) would require a special lower or a mag block, a special bolt, special buffer, special magazines, etc.

Of course it depends on where you're starting, but for the guy who wants to expand his current AR into a subsonic platform, you'd have to shoot a lot of re-loaded 10mm/.40 cal hunting/defense cartridges to overcome the difference in hardware costs with reduced bullet cost ($0.20 ish vs $0.50 ish).

 

[jmorris]

the shape of the bullet matters a lot.

1.9” difference at 150 yds for 200’s one with a .163 BC and the other .660 both going 1050. Both zeroed at 100 the 40 is -13.7 the .30 is -11.8 both close to a foot of drop in 50 yards and it gets worse after that quickly.

Quickly being in the 10 yards separating 290 yards from 300, the .30 cal bullet had 8.6” of drop for a total of over 8 feet of drop from its 100 yard zero.

 

[ATLDave]

If you want a subsonic projectile to be tracing something other than a sliding-down-the-rainbow trajectory at 250+ yards, you'd better give it wings or backspin.

 

[mavracer]

I shoot coyotes with a 9mm AR, sub 147’s with point click results.

View attachment 819905


Hogs with a 458 subs and thermal.

View attachment 819906

I’ll figure out what to do with the 300 one of these days.

Oh heck yeah spend a couple grand to build 2 rifles, $400 on tax stamps several hours building suppressors just to make coyotes and hogs somehow deader. Genius

 

[jmorris]

Doesn’t make them any “deader” but it doesn’t wake up the wife when I shoot one from the balcony upstairs.

Blast off one of my loud ones in the middle of the night when my wife is sleeping and the results could be quite negative. As they say, happy wife, happy life.

 

[CoalTrain49]

Seems like the pistol calibers would have the advantage of more compact magazines and cheaper practice ammo.

If the OP is going to build one or the other I'm not seeing a huge difference in cost except for ammo. The 10 mm wins that one.

 

[mavracer]

If the OP is going to build one or the other I'm not seeing a huge difference in cost except for ammo. The 10 mm wins that one.

Is there a lot of cheap subsonic 10mm available. My guess would be no especially from the longer barrel of a SBR or carbine.
Reloads to Reloads isn't going to be much cost difference.

The last blackout upper I built cost $200 with bolt and uses cheap P-mags. Where's a 10mm upper close to that.

 

[bearcreek]

The last blackout upper I built cost $200 with bolt and uses cheap P-mags. Where's a 10mm upper close to that.

Some of this is personal preference I suppose. I tend to gravitate toward good quality stuff. I want my **** to be capable of holding up long term, even if I don't actually need it to. A $200 complete upper, ( I'm just taking your word that such a thing actually exists) in any caliber, is going to be the very bottom of the barrel as far as quality.

 

[bearcreek]

If you want a subsonic projectile to be tracing something other than a sliding-down-the-rainbow trajectory at 250+ yards, you'd better give it wings or backspin.

That was my thoughts. This isn't going to be a long range weapon, no matter what cartridge it is. No matter what the BC is, you can only do so much with a bullet that starts out moving less than three times the speed of an arrow from a modern compound bow. Inside of 150 yards or so, the differences between these various bullets seem to be very minimal.

 

[ATLDave]

Reloads to Reloads isn't going to be much cost difference.

for
If you're just looking at powder-coated 200 grainers, at SNS its about $60/500 for the .3's and $48/500 for the .4's. You can bump up to $52/500 for the 220 .4's.

500 new Starline cases will cost you $131 for the .3 and $99 for the .4.

I suspect the modest charge of pistol powder that would power the subsonic 10 is going to be less than that used for subsonic .300 rounds, though I'm a little less knowledgeable about that.

Are any of these "much cost difference?" Depends on your volume of shooting and your wallet.

 

[mavracer]

for
If you're just looking at powder-coated 200 grainers, at SNS its about $60/500 for the .3's and $48/500 for the .4's. You can bump up to $52/500 for the 220 .4's.

500 new Starline cases will cost you $131 for the .3 and $99 for the .4.

I suspect the modest charge of pistol powder that would power the subsonic 10 is going to be less than that used for subsonic .300 rounds, though I'm a little less knowledgeable about that.

Are any of these "much cost difference?" Depends on your volume of shooting and your wallet.

LOL what kind of idiot buys starline blackout brass when you can buy prepped milsurp brass ready to load for less than 1/2 that.

Some of this is personal preference I suppose. I tend to gravitate toward good quality stuff. I want my **** to be capable of holding up long term, even if I don't actually need it to. A $200 complete upper, ( I'm just taking your word that such a thing actually exists) in any caliber, is going to be the very bottom of the barrel as far as quality.

You do you, I've found after building and shooting a couple dozen ARs that spending a bunch of money to have a some upper end name on the box that there's really no difference between a $40 no name milspec upper and $150 ones lap the barrel and torque the nut properly and they'll shoot the same. Same goes for handguards, gas blocks and gas tubes, barrels are the place spending money can be important when I want a 1/2 MOA or less I'll spend some but for a blackout that I'm going to be putting a red dot on that's a waste.this one still shoots 1.2-1.5 moa consistently.

 

[CoalTrain49]

Is there a lot of cheap subsonic 10mm available. My guess would be no especially from the longer barrel of a SBR or carbine.
Reloads to Reloads isn't going to be much cost difference.

The last blackout upper I built cost $200 with bolt and uses cheap P-mags. Where's a 10mm upper close to that.

You're correct. The 10mm ammo is probably always going to be super, at least the factory stuff. I was going on the assumption that the OP knew that although that's not what he said.

I don't think there are any that cheap. About $500 is the cheapest I could find. $300 difference wouldn't stop me tho especially if you shoot as much as I do.

 

[bearcreek]

You're correct. The 10mm ammo is probably always going to be super, at least the factory stuff. I was going on the assumption that the OP knew that although that's not what he said.

I did know that. It'd be easy to load myself though. Another thing the pistol cartridges have going for them is ease of reloading. The ammo availability aspect is also why I mentioned the possibility of .40 S&W. 10 mm has no advantage over .40 (that I know of) if the goal is strictly subsonic velocities.

 

[CoalTrain49]

LOL what kind of idiot buys starline blackout brass when you can buy prepped milsurp brass ready to load for less than 1/2 that.

You don't have to buy 300 blk brass. Pick up 5.56 at the range. Just chop it, size it and trim it for 300 blk.

10 mm brass isn't laying around like 5.56 although I do find some from time to time. I don't know anyone who shoots it.

I've considered 300 blk but stayed with 5.56 because I can load it for 0.20/rd and I shoot a lot of it.

I'll buy a PCC at some point just because but I doubt it will be 10 mm, probably 45 acp because I'm deep into that cartridge already.

 

[ATLDave]

I did know that. It'd be easy to load myself though. Another thing the pistol cartridges have going for them is ease of reloading. The ammo availability aspect is also why I mentioned the possibility of .40 S&W. 10 mm has no advantage over .40 (that I know of) if the goal is strictly subsonic velocities.

Not 100% sure you can get a 220 to fit in a 40 chamber without a lot of reaming.

 

[CoalTrain49]

I did know that. It'd be easy to load myself though. Another thing the pistol cartridges have going for them is ease of reloading. The ammo availability aspect is also why I mentioned the possibility of .40 S&W. 10 mm has no advantage over .40 (that I know of) if the goal is strictly subsonic velocities.

40 is a good bet. I see a lot of that brass at the range. Lots of LE trade in pistols dirt cheap now also.

 

[bearcreek]

The other thought I've had about all this is that if I built a l

40 is a good bet. I see a lot of that brass at the range. Lots of LE trade in pistols dirt cheap now also.

Cool thing about that too would be that the lower could be used with a 9mm upper as well, for cheap practice. I cast my own 9mm, which makes it cheaper to shoot than .22 LR.

 

[someguy2800]

I might have missed it but what is this actually going to get used for? If its just a range plinker I think I would just simplify my life and do a 9mm loaded with 147 or 160 cast bullets. If your just banging steel and stuff whats the difference?

I have a 300 blackout and a 9mm AR. 300 blk is a great fun caliber in sub and super and really reaches out compared to a pistol round. Something that has been overlooked in the discussions of drop and velocity is wind drift. The drop between my 9mm and 300 blackout are not that different, but the pistol bullets practically blow away like tumbleweeds compared to the 225 grain ELD bullets in the 300 blackout. I want to say the difference was 3 or 4 times more wind drift in the 9mm vs 300 blackout at 200 yards. Even at 100 yards the wind drift is substantial. The 9mm is pretty hard to hit anything with at 200 yards if the wind is blowing, or you walk it on target to figure out the drift. The 300 blackout even subsonic with the heavy ELD bullets doesn't have any more drift than a 223.

 

[Zaydok Allen]

10 mm has no advantage over .40 (that I know of) if the goal is strictly subsonic velocities

1000 pieces of Starline 10mm brass is only $162. Powder isn't that expensive. I guess even if you were strictly going subsonic, I don't know why you'd limit yourself if you are willing to load your own.

 

[CraigC]

I cast my own 9mm, which makes it cheaper to shoot than .22 LR.

I've never heard that said where it was actually true.

 

[Wreck-n-Crew]

I think the point was just made that makes more since than anything to me. So question... why not just a 40 ? I get it...10mm is cool but making it as weak as a 40 then it might as well be a 40. Otherwise its like buying a 357 mag just for shooting 38's only.

Fun discussion, but for me personally the OP is answered . Have fun! {{{{Poof}}}}

 

[bearcreek]

1000 pieces of Starline 10mm brass is only $162. Powder isn't that expensive. I guess even if you were strictly going subsonic, I don't know why you'd limit yourself if you are willing to load your own.

I get what you're saying. I'm not really a fan of .40 S&W to be honest. Really the only reason would be what I said in post #43. The ability to use a 9mm upper on the same lower.

 

[bearcreek]

I've never heard that said where it was actually true.

You got me. I stand corrected. Honestly I haven't really looked at .22LR prices since the drought a few years ago. I haven't bought any .22 ammo in probably 8 to 10 years. My 9mm brass is free since it's range pickup and the bullet material generally costs little or nothing either. Powder and primers run about $.06/rd. Back during the .22 shortage, my reloads were cheaper but that no longer appears to be the case.

 

[someguy2800]

I remember reading about a company that was making a 300 grain 45 acp bullet with a boat tail base that would fit in a normal 45 acp case. That would be an awsome round in a suppressed AR PCC.