CAR 5.56 Velocity Loss

DJetAce · Jul 28, 2004

From Ar15.com Ammo Oracle

Here's some Q3131A (M193) ballistic data:
Altitude 1480 feet 70 degrees 50% humidity. 55gr FMJBT Average cD over velocities: .267

20 inch barrel: MV=3250.0 FPS
Energy=1289.70 FP And you will hit 2700 around 150 yard mark.

And for a 16" barrel: MV=3100.0 fps. Energy=1173.4 fp. And you will hit 2700 around 100 yard mark.

Now that's a loss of 150fps for 4 inches in barrel.
My 15 inch barrel AR (with a 2 inch muzzle break) gives this figure using Lake City Military M193

MV=3030 fps (5 shot average)
Energy=around 1100 fp.

That's a loss of 70 fps for ONE inch of barrel (shorter you go the more you will lose per inch.)

Now you have 4 more inches to lose before you hit gunkid's 11 CAR. That's at least 280 fps.

So you are talking about 2750 fps at the MOST for a 55 grain military round. The thresh hold of fragmentation IS 2700! And that is why the CAR was well known to be ineffective in Vietnam even at 25 yards!

Add to this, if you use HEAVY bullets, the velocity goes down even further. 11 CAR is NOT the way to go if you wish to use the 5.56mm.

mrostov · Jul 28, 2004

Some of those here don't understand things in math like logarithmic changes and bell curves - i.e. everything is linear.

An 11" CAR is a lot like packing a mildly hotter than normal .22 Hornet.

andy · Jul 28, 2004

u r fos, as I've already demoed. A 22 hornet is 45 grs at 2600 fps, 600 ft lbs. M855 Lake City, from an 11" barrel, is 2700-2800 fps,(62 gr ball ammo) depending upon the lot of ammo you test. With good handloads, it's 2800+ fps, with a 60 gr sp. That's 1040 ft lbs, 5x the 220 ft lbs you THINK is ok to fight with, at 10 ft, in your stupid makarov. The 11" CAR still has the Makarov beat at 500m,*****. It's got 55% more power than the Hornet has, *****. Just because you are too cheap to really find OUT, doesn't mean others are, you know. You've never shot an11"223 in your LIFE,much less chronoed full charge 5.56 ammo thru one.

andy · Jul 28, 2004

if u r STUPID, and COUNT upon ball ammo, and BELIEVE the bs you read on the net, about velocities and 'minimums for fragging". I belive in good SOFTPOINT ammo,and I aint too cheap or lazy to handload plenty of it, either, unlike you *******.

What it all comes down, to, tho, is you are too lazy, cheap, inept, chicken****, etc,to makeor buy a CAN for a Car-15,so you HAVE to run down the ballistics. That can, and the HANDINESS of a CANNED 11" barrel are worth more than a 100 ******* like you.

andy · Jul 28, 2004

Winchester White box delivers 2950 fps in a 16" barrel, 2650 in an 11" barrel, and it is 48,000 CUP 223 SAAMI spec, not 55,000 CUP 5.56 pressure levels, *****.

andy · Jul 28, 2004

now maybe you "think' another 13% of pressure DOESN'T add another 200 fps, but you're fos if so. good sp's still work FINE down to 1800 fps, which the 11" CAR still has at about 230m. Those of you who are so SURE an 11" 223 has NO power or accuracy left at 300m are WELCOME to take me up on my challenge. Give me ONE shot at your standing, frontal torso, from the bipod,scoped 11" 223, at 300m, and then I will stand there and let you shoot back at me all you CAN.

Like I said, I'd LOVE to watch you flop around, bleeding out, for 30 seconds, thru the scope, then walk up and piss on your STUPID face.

TODD 3465 · Jul 28, 2004

Jeez, reality sure does give him real fits.

No you do it standing 300m.

Then let me shoot back the same way with MY preferred rifle.~>;-)

mrostov · Jul 28, 2004

GunKid said:
What it all comes down, to, tho, is you are too lazy, cheap, inept, chicken****, etc,to makeor buy a CAN for a Car-15

Oh, you mean like "too lazy, cheap, inept, chicken****, etc," to go to prison like you did for a zillion years for just an inanimate hunk of metal?

The fact is that you use it as a crutch, like it's quick fix cure all. It's the same eazy money mentality that has caused you other difficulties, it's just that when THIS scheme to cheat with a perceived shortcut turns to sh^t, it'll probably get you killed.

Yeah, the shortness of the 11.5" commando barrel is handy, but it's still a marginal weapon, especially the further you get past 50m.

Your inability to do math and propensity to lean the figures in your direction doesn't change the marginal capabilities of your favorite weapon. The only person you're misleading is yourself.

The 16" barrel is so far superior ballisticaly to the 11.5" it's laughable. The difference isn't linear either.

Out of an 11.5" barrel and a military powder load, a 55gr bullet drops down to 2700fps within 45m and a 62gr bullet drops down to 2700fps within 15m.

Out of an 16" barrel and a military powder load, a 55gr bullet drops down to 2700fps within 150m and a 62gr bullet drops down to 2700fps within 95m.

A major difference, huh?

Your 11.5" barrel is NOT a serious 200m - 300m weapon, even if it was accurate, which it probably isn't. It is a marginal performer, at best.

As for 'ball' ammo, myself, I like the military spec M193 load with a cannelured bullet (not just any 55gr fmj load) because within effective range where it will fragment, it can actually be deadlier than a hunting bullet.

As usual, you're stretching the ballistics on paper in favor of the gear you like and low balling it in favor of that which you don't.

Again, you compare apples and oranges. A Mak is a very accurate, safe to carry, small handgun which a 10 year old can carry and shoot. It's a pistol, a small one, that you compare to a rifle.

You really do need to get a bit more range experience with these weapon systems.

There is an approach to making the 11.5" CAR-15 a lot more effective and accurate, actually something I might not mind carrying under some circumstances, but you're not approaching it correctly and obviously haven't figured it out yet.

It's rather simple. Shall I clue you in?

RIKA · Jul 28, 2004

Our master shottist likes to go ballistic when challenged with facts. People with that much lack of emotional control shouldn't own weapons.

RIKA

John in AR · Jul 28, 2004

mrostov said:
...There is an approach to making the 11.5" CAR-15 a lot more effective and accurate, actually something I might not mind carrying under some circumstances, but you're not approaching it correctly and obviously haven't figured it out yet.

It's rather simple. Shall I clue you in?...

Assuming the goal is primarily increased velocity, polygonal and/or "gain twist" rifling comes to mind, but have no real experience with either.

Just a guess.

mrostov · Jul 28, 2004

GK's fixated on pure velocity, taking a smaller and smaller bullet and trying to drive it faster and faster with yet more powder and a bigger fireball. Hard on the gun, poor accuracy, rapidly reaches a point of diminishing returns.

I'm just looking at what the US military is using with the shorter barrel rifles after a lot of trial & error plus field testing in Afghanistan. The best conventional style round they've found to date out of a short barreled rifle, without one of the new weird exotic bullets, is the Black Hills load of the 77gr Sierra FMJBTHP Match bullet, also called the OTM - Open Tip Match. It gets reliable fragmentation down to 2100fps.

The barrels the SF guys have been using are the 14.5", so the range would still be less with the 11.5". Still no substitute for a longer barrel.

If GK wants to keep that 11.5" length in his barrel and get whatever performance he can out of it, what he needs to do is ditch the 1:9 barrel and get a nice chrome lined Colt Commando 1:7 barrel. It'll run bullets down to 55gr pretty well.

It'll still not be a long range wonder, but it'll perform better than what he's got rigged now.

John in AR · Jul 28, 2004

Mike -

Just curious about your opinion on something. I'll likely use my CAR-15 (Bushmaster; 1-in-9 twist) for whitetail this fall, and was planning to use my normal 55-grain Remington SP carry load instead of a heavier-bullet "hunting" load, due to the shorter barrel.

In your opinion, would you expect the 77-gr Black Hills to be a better option? (Our deer aren't very large.) Obviously, I can test accuracy, reliability, etc before season starts, but won't have a chance to test terminal performance before it's "for real".

Thanks

[What about the polygonal/gain-twist idea...? Seems like that could be a big help for short-barrel rifles.]

mrostov · Jul 28, 2004

The polygonal rifling idea has some merit. I'd like to try it out if there are barrels being made like that for the AR. My HK91 only had a 17.8" barrel and it's polygonally rifled barrel preformed like a champ.

In theory at least, polygonal rifling is supposed to increase your muzzle velocity by small, but noticeable margin.

The 55gr in AR can drop a deer, no problem. A lot of deer hunters that use the AR seem to like the Winchester 64gr Power Point, which uses a bullet that was designed specifically for deer. For deer that's what I prefer when I'm using the AR.

John in AR · Jul 28, 2004

The reason I mention the 'gain twist' thing was due to reading an article recently on a suppressed, short-barrel AR variant. Something like 10-11 inch barrel, iirc, but supposedly gave higher velocities than the 14.5 inch M4.

If true, it could push a bullet from a 16" gun faster than from a normal 20" barrel. I may look around & see if I can find the article.

DJetAce · Jul 28, 2004

Gunkid, U R sadly mistaken. While I would agree the 63gr military does chrono out at 2700 fps or so from a 16 inch barrel, YOU DON'T HAVE A 16 INCH BARREL! Yours is a 11 inch tube. That will cost you another 200 fps or more!

Ever wonder why the CAR has such a large flash suppresor? Cause all that power is burned in the AIR instead of in a bore, and thus you lose a huge amount of velocity. The Army stopped using the CAR for that reason more than any other.

You must also keep in mind that in any SHTF dream that you won't have your reloads or any fancy ammo. Beggars are not choosers as they say. You will shoot what you find to shoot. The CAR is for losers. If you are going to go the AR route, get the 20 incher for all around use. You can still attach your silly 'can' on it and the .22 unit (but I doubt the .22 lr unit will shoot the same place with the sights, so I would just carry a light weight .22 pistol myself.)

John in AR, I would suggest the Spear 70gr simi-spinzer softpoint handloaded. And then only for broadside shots that hit little bone. If you want a factory load, the Winchester 63 grain power point will do the job to. Same limitations.

John in AR · Jul 29, 2004

DJet - Thanks, but I don't reload the 5.56 and don't figure to start in the near future. I've thought about the Winchester power point ammo, but with my gun's short barrel (and inherent velocity losss), am more inclined to stick with the 55-grainers.

Rostov -

Found the article, it's in the current "Special Weapons for Military & Police"; reviewing the Arms Tech "Compak 16". Stubby AR variant, with 9.5" barrel using both polygonal and gain-twist aspects in the rifling. The gun actually got slightly more velocity than a standard 14.5" M4. (2703 fps vs 2697 fps with SS109 ball). Sounds almost irrelevant until you consider that the M4's barrel is 52% longer, yet gains nothing in velocity.

They claim the 14.5" version gives velocities "comparable" to a standard 20" AR barrel; if anywhere close to true, a 16" civilian version should easily at least match the 20" guns.

Wonder what a full 20" version could do...

mrostov · Jul 29, 2004

Hmm, interesting. Arms Tech is right here in town too.

Found an outfit named Pac-Nor that will make a custom AR barrel with polygonal rifling.

http://www.pac-nor.com/ar/

1911sr · Jul 29, 2004

There's no reason to post data on the .223 or .308 cuz he hasn't a clue about either.
The .22 and .30 caliber are specialties of ours and we have REAMS of load data we've logged over 45 years for Dad and 10 years for me. Its SO embarassing to read this dumbstuff that GK posts about ballistics, reloading and load data. Its bad enough looking stupid on one or two websites, but to have the entire WORLD of reloaders know how stupid and inexperienced he is must be painful to say the least, no?

1911sr

mrostov · Jul 29, 2004

Hey, she's here!

Good to see you.

Aslan · Jul 29, 2004

Hey 1911sr - glad to see you!

:wavey:

:devil:

CAR 5.56 Velocity Loss

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