300 HAM’R

[firemn260]

I like the 220gr subs in my 10.5" 300BLK with the Rugged 45, it's really quiet. I can't reload for 300BLK right now but the 150gr sub sounds interesting.

I just picked up my rugged 45 the other day after a year of waiting. I mainly wanted it for my sons 350 legend and I liked the fact that the obsidian was so versatile. It’s not as quiet on my 300 blk as my omega but quiet enough. I also like the fact I can take it apart to clean it.

 

[firemn260]

Thank you, sir!

thanky

No problem. If I remember correctly I had to mess with the seating depth too. I seat them just below the cannelure and that seems to be the sweet spot in my gun.
I know there are a lot of people out there who hate on the blk but for me, it is the most cost effective cartridge for high volume shooting. 1680 is pretty easy to find, I buy the 150s in bulk and form all my cases from the 55 gallon drum of 5.56 brass I’ve managed to stockpile. As far as primers the last thousand I loaded was with some old Win staynless primers that where in wood trays. 1680 does crud up the gun something fierce though.

 

[smdub]

Why load 150gr BLK sub vs 147+gr 9mm subs? 9 is even cheaper to load. I guess there are small differences in BC. I'll go look that up. I've only loaded 220gr+ BLK subs as that is something that cant be done easily otherwise.
230gr 45s are much lower BC - not that it makes much difference out to 100yds where I usually shoot. Will make a bigger difference at 300yds at delmarva though. Again, I'd have to go do the math using the difference BCs. I don't have anyway to shoot 45 from an AR though. Double stack mags don't fit in a normal AR magwell.

Edit:
Big BC difference.
147gr 9mm ~0.160 (>950fps)
150gr 308 FMJBT ~0.387 (<1800fps. I suspect it goes down more @ subsonic. Will look for info.)
150gr 308 spitzer ~0.360 (<1800fps. Again, I suspect this don't hold at subsonic velocities)

 

[firemn260]

Why load 150gr BLK sub vs 147+gr 9mm subs? 9 is even cheaper to load. I guess there are small differences in BC. I'll go look that up. I've only loaded 220gr+ BLK subs as that is something that cant be done easily otherwise.
230gr 45s are much lower BC - not that it makes much difference out to 100yds where I usually shoot. Will make a bigger difference at 300yds at delmarva though. Again, I'd have to go do the math using the difference BCs. I don't have anyway to shoot 45 from an AR though. Double stack mags don't fit in a normal AR magwell.



Edit:
Big BC difference.
147gr 9mm ~0.160 (>950fps)
150gr 308 FMJBT ~0.387 (<1800fps. I suspect it goes up more subsonic. Will look for info.)
150gr 308 spitzer ~0.360 (<1800fps. Again, I suspect this don't hold at subsonic velocities)

That’s a legitimate question and it’s one that I ask myself every time I get the urge to put together a pistol caliber AR. I guess it comes down to the fact that I already have a pistol and rifle chambered in 300 and they cover my fun suppressed shooting needs. I’ve seen some 147gr 9mm for around 14 cents a bullet compared to 30cal 150s at around 23 cent per bullet. If I where to use the heavier bullets the cost per round would go up significantly. I don’t currently load 9 mm so that would be another cost. I was basically just looking for the most cost efficient subsonic ammo I could load for the blk. I actually have a large stockpile of 30 cal projectiles that I got from a guy who was loading for a Garand and a 300 win. Most heavies I have are all match grade bullets from 180 up to 220gr. I can imagine the disgust I would get from people if they knew I was plinking away with subsonic Berger VLD bullets but I got it all for next to nothing.

I do appreciate you taking the time to look up and compare the ballistic data though.

 

[smdub]

Nothing wrong w/ shooting it because that is what you have avail!

I did a quick online calculator of ballistics. 147gr 9mm vs 150gr 7.62x39. I set muzzle velocity of both at 950fps.
100yd the 7.62 has 0.080" less drop. By 300yd its 12" less (but thats only a 9% difference 141" vs 129")
100yd the 7.62 has 30fps advantage. By 300yd its 70fps faster (but only same 9% difference)
So the BC is making less of a difference than I thought. At subsonic speeds not nearly as much drag.

Extreme carries 147gr 9mm for ~$0.10. Berry's is $0.12. 9mm subs take only a couple grains of powder (depends on exact powder of course.) Probably around 1/3 the powder you're using for the 300. The savings add up.

All I have is 220gr match rounds for 300BLK. Everything from Amax, Nosler, and Hornady match. The only heavies that were available at that time. Bought a ton when they were cheap and paid $0.23-$0.30/rd. Many of them are overruns or blems. Not sure what they'd cost today. Berrys now makes a 220gr for 300 sub that is ~$0.30 currently. Everglades carries a 220gr plated for 300 for $0.32 and is in stock. If I went on a 300 loading kick today it would probably make sense for me to buy new plated rounds and sell off the match stuff.

Sorry to drag the 300 HAMR discussion off topic. HAMR looks interesting but it falls into the 6.5/6.8/etc type niche rounds IMO. Haven't been convinced yet to jump into any of them. As I don't hunt, I really don't have a 'need' for any of them other than a 'want'. I'm a big bore junkie so a 458 SOCOM or 50 BEO would prob get my $ first realistically. Its neat to follow its development/progress though. Choices are good.

 

[outrider58]

Nothing wrong w/ shooting it because that is what you have avail!

I did a quick online calculator of ballistics. 147gr 9mm vs 150gr 7.62x39. I set muzzle velocity of both at 950fps.
100yd the 7.62 has 0.080" less drop. By 300yd its 12" less (but thats only a 9% difference 141" vs 129")
100yd the 7.62 has 30fps advantage. By 300yd its 70fps faster (but only same 9% difference)
So the BC is making less of a difference than I thought. At subsonic speeds not nearly as much drag.

Extreme carries 147gr 9mm for ~$0.10. Berry's is $0.12. 9mm subs take only a couple grains of powder (depends on exact powder of course.) Probably around 1/3 the powder you're using for the 300. The savings add up.

All I have is 220gr match rounds for 300BLK. Everything from Amax, Nosler, and Hornady match. The only heavies that were available at that time. Bought a ton when they were cheap and paid $0.23-$0.30/rd. Many of them are overruns or blems. Not sure what they'd cost today. Berrys now makes a 220gr for 300 sub that is ~$0.30 currently. Everglades carries a 220gr plated for 300 for $0.32 and is in stock. If I went on a 300 loading kick today it would probably make sense for me to buy new plated rounds and sell off the match stuff.

Sorry to drag the 300 HAMR discussion off topic. HAMR looks interesting but it falls into the 6.5/6.8/etc type niche rounds IMO. Haven't been convinced yet to jump into any of them. As I don't hunt, I really don't have a 'need' for any of them other than a 'want'. I'm a big bore junkie so a 458 SOCOM or 50 BEO would prob get my $ first realistically. Its neat to follow its development/progress though. Choices are good.

Aerodynamics tends to have less/little effect at subsonic speeds. Is it because friction is lower at slower speeds? Trying to wrap my head around this.

 

[RRomig]

Top fuel cars get over 200 mph in the 1/8 mile from a standing start. In the next 1/8 mile with a rolling 200+ mph start they only get another 100 mph. I’m pretty sure it’s all about air drag.

 

[smdub]

Drag is square law. To go 2x as fast, the drag increases by a factor of 4. Thats in the subsonic region. I don't know much about supersonic but odd things happen there. Took airplanes a good bit more energy to push through the sound barier so non-linear things are going on.

 

[lazarus]

Why load 150gr BLK sub vs 147+gr 9mm subs? 9 is even cheaper to load. I guess there are small differences in BC. I'll go look that up. I've only loaded 220gr+ BLK subs as that is something that cant be done easily otherwise.
230gr 45s are much lower BC - not that it makes much difference out to 100yds where I usually shoot. Will make a bigger difference at 300yds at delmarva though. Again, I'd have to go do the math using the difference BCs. I don't have anyway to shoot 45 from an AR though. Double stack mags don't fit in a normal AR magwell.

Edit:
Big BC difference.
147gr 9mm ~0.160 (>950fps)
150gr 308 FMJBT ~0.387 (<1800fps. I suspect it goes down more @ subsonic. Will look for info.)
150gr 308 spitzer ~0.360 (<1800fps. Again, I suspect this don't hold at subsonic velocities)

What you found. For the guy that is going to plink at 100 or less, or is shooting varmints suppressed AND at those fairly short 100yd or less ranges, than a 9mm with subs or a 45acp with heavier weight bullets is a MUCH better choice. Especially if shooting varmints. Yes, a heavy 300 BO might tumble and you can get stuff that expands, but on something like a ground hog, coon, or fox, possibly even something a little bigger like a coyote a designed for expansion 147 or 158gr .355 bullet is generally going to do more damage than a 190-220gr .308. And it'll for SURE be a hell of a lot cheaper to load, for example, 147 XTPs for cheap compared to a 190-220 .308 that is designed to expand at subsonic velocities.

And then you get to a 45 where you can push a 230 up to ~1000fps out of a 16" barrel and just about any decently constructed .45acp JHP is going to expand to .6-.9 inches with the kinds of velocities you'll get within 100yds with a starting velocity around 1000.

Or another option, a suppressed .357 or 45LC lever gun loaded at fast subsonic velocities using 38spc heavy hollow points or 45LC hollow points. Hornady has two 158gr .357 bullets, one really designed for a +p 38spc and one designed for a hot magnum or rifle load. So load up a 357 cartridge to about 1050fps using the lighter constructed .357 XTP 158gr and turn groundhogs inside out.

That said, just about any of these is going to end a varmint pretty easily so long as you don't miss or graze it. A 22 will kill most up to a Coyote unless its a really bad hit. Though with a 22 it might get away to die later if it isn't a good hit.

My biggest thing is I'd want it with a closed breach system. A bolt gun, gas operated, radial delayed, etc.

 

[lazarus]

Top fuel cars get over 200 mph in the 1/8 mile from a standing start. In the next 1/8 mile with a rolling 200+ mph start they only get another 100 mph. I’m pretty sure it’s all about air drag.

For drag air resistance isn't much of a problem.

X = 1/2AT^2+VT
V = AT

X = distance
A= acceleration
T= time
V= initial velocity

So to hit 200mph (293fps) at 1/8 mile (720 feet) you'd take about 5 seconds at about 58fps^2 of acceleration (average of 1.8G's).

If you maintained that acceleration average for another 1/8th of a mile you'd end up hitting the quarter at about 7.1 seconds (just another 2.1 seconds) and added another 123fps, or 84mph...

These things have such a CRAZY amount of power, they are limited by traction for the first few hundred feet and drag really only begins to have any real impact until they'd be going closer to 1/3-1/2 a mile. Don't get me wrong, drag DOES impact it, but we are talking a few mph and hundredths of a second. The difference in power and traction of the dragsters have a much bigger impact. These are suckers making like 2000-4000hp and if they had sufficient running room and their tires and fuel supplies held up, they could easily push 600+mph.

 

[lazarus]

Drag is square law. To go 2x as fast, the drag increases by a factor of 4. Thats in the subsonic region. I don't know much about supersonic but odd things happen there. Took airplanes a good bit more energy to push through the sound barier so non-linear things are going on.

The coefficient of drag changes (usually not better, but a lot depends on the shape of the object). The biggest issue for breaking the sound barrier was the shape we were trying to do it with was not remotely optimized for supersonic and transonic speeds. Both stability and drag.

Drag does drastically increase right at transonic speeds, but then goes back down once you are supersonic (I forget the exact realm, but IIRC it is between about mach .97 and 1.03 or something like that). So for a given amount of power, if you do break the sound barrier, you can maintain a higher speed than right at the sound barrier. Basically it takes less power to maintain mach 1.05 than it does mach .99. I don't remember off the top of my head roughly what we are talking (and the shape again has a big impact). The drag increase is not SO much faster that you can break the sound barrier and just cruise along at mach 2 for the same energy as mach .99.

Of course, an airfoil and a projectile are two different things, and they don't entirely deal with the same issues (the coefficient critical number is extremely high for a spitzer shape).

Drag-divergence Mach number - Wikipedia

en.wikipedia.org

 

[lazarus]

Aerodynamics tends to have less/little effect at subsonic speeds. Is it because friction is lower at slower speeds? Trying to wrap my head around this.

Yup. Because of drag divergent mach numbers, basically a supersonic projectile has more drag than a subsonic projectile. So it is more than the simple 3rd power law (takes 8x the power for 2x the speed, or another way of saying things slow down a lot more rapidly the faster they go). And once you get near and over supersonic, this increases more than what the speed increase should indicate.

This is partly what the G1 and G7 ballistic coefficient attempt to take into account is the more realistic supersonic drag, rather than something someone is calculating at subsonic speeds.

Supersonic speeds create a shockwave on the surface of the object which basically builds up extra drag (it's a literal wave front of air/sound. If you looked at the bow wave of a boat, think of it like that, but in air). The shockwave extends out and around the object creating more drag than just what the object itself produces at slower speeds.

Aerodynamics has a lot of impact at subsonic speeds too. It is a little less, but a lot of it is that most people shooting any kind of subsonics usually isn't doing it at very long ranges. Shooting a 22lr 40 sub versus a 300BO 220gr sub.

The 22lr with a 100yd zero has 44.8" of drop at 200 and 147" at 300yds. That 300BO is 35" at 200 and 109" at 300. The 22lr has slowed to 695fps and the 300BO has only slowed to 924fps.

At 1500fps it is 27" and 94" vs 16" and 51". And the 22lr dropped to 817fps at 300yds and the 300BO is still going 1266fps.

So a reasonable difference on the subs with the big difference in aerodynamic drag (I used .12 G1 and .70 G1 for the two respectively).

At subsonic velocities and 300yds, there is a 35% reduction in drop by going with the much lower drag 300BO bullet, but at low supersonic velocities it is an 84% reduction in drop. If you kept going out further for the 300BO to drop subsonic the difference would against start to close up more towards the subsonic end of things.

That's why a slippery bullet is so much better at long ranges, even though that usually means it is a heavier and slower bullet. Some of it too is if they both have the same energy, the faster and lower BC bullet is spending more of its energy on air friction, even if the ballistic coefficient was identical, which it isn't. Of course the faster and lower BC bullet can make up for that in trajectory at shorter ranges. And in many cases, you aren't going to realistically engage a target at a long enough range for the higher BC slower bullet to outperform the heavier bullet.

If you are shooting at 400 or 500yds with big boy cartridges, a lighter weight identical construction bullet will outperform the heavy and slower bullet, despite the large difference in BC. Of course, the heavier bullet is going to have more delivered energy on target and if you are shooting things, that is important (plus penetration). I'd rather hit an Elk with a 180gr .308 than a 130gr .308 even if the 130 has a much better ballistic trajectory at 300yds than the 180gr does as the 180 is carrying a fair amount more energy and will penetrate significantly deeper. Against an antelope I'd probably rather the 130gr at 300yds instead.