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Posted: 6/2/2010 7:01:46 PM EDT
Another thread got me thinking ........

If a .223 - 7.5"  AR is loaded with Hornady  75g  BTHPs  to 2,000fps it would generate about   700ftlbs of energy.

If a 357Sig 16.5" AR is loaded with Speer 115g Gold Dot's to 2,000fps it would generate about 1,000ftlbs of energy
(w/ max load of Power Pistol Powder)


Is the   .223   "rifle round"  now  going too  slow to penetrate a  std Kevlar vest?  (assume IIIA)
Is the 357Sig "pistol round" now going so fast it will  penetrate a std Kevlar vest? (assume IIIA)


How does all this work?
Projectile diameter must have some bearing on this, I guess.
Link Posted: 6/2/2010 7:07:03 PM EDT
Could the magazine fit inside a pistol grip that an average sized human hand could wrap around enough to effectively control the weapon?
Link Posted: 6/2/2010 7:26:17 PM EDT
The transition takes place at the .30 carbine.
Link Posted: 6/2/2010 7:55:31 PM EDT
Originally Posted By thecreeper23:
The transition takes place at the .30 carbine.


This.
Link Posted: 6/2/2010 7:55:45 PM EDT
At about 50-yards...so why IS the sky blue?
Link Posted: 6/2/2010 8:32:47 PM EDT
Originally Posted By thecreeper23:
The transition takes place at the .30 carbine.


Exact same thing I thought when I read the thread title.


Posted Via AR15.Com Mobile
Link Posted: 6/2/2010 8:36:49 PM EDT
Originally Posted By wombat25:
Originally Posted By thecreeper23:
The transition takes place at the .30 carbine.


Exact same thing I thought when I read the thread title.


Posted Via AR15.Com Mobile


I guess all great minds think alike. I knew there could only be one real answer.

Link Posted: 6/4/2010 1:23:56 AM EDT
[Last Edit: 6/4/2010 1:24:16 AM EDT by tt350z]
.30 cal, really?

So that 9mm, .357, .40, .45 are all rifle caliber since they exceed the .30 cal, and rounds such as .243 Winchester, 6.5x47 Lapua, etc. are all now pistol rounds...
Link Posted: 6/4/2010 5:01:14 AM EDT
Originally Posted By tt350z:
.30 cal, really?

So that 9mm, .357, .40, .45 are all rifle caliber since they exceed the .30 cal, and rounds such as .243 Winchester, 6.5x47 Lapua, etc. are all now pistol rounds...


.30 caliber is the size of the bullet, not the length of the case.
Link Posted: 6/4/2010 5:19:47 AM EDT
Link Posted: 6/4/2010 6:31:46 AM EDT
Originally Posted By Eric802:
Originally Posted By Merdoc:
Originally Posted By tt350z:
.30 cal, really?

So that 9mm, .357, .40, .45 are all rifle caliber since they exceed the .30 cal, and rounds such as .243 Winchester, 6.5x47 Lapua, etc. are all now pistol rounds...


.30 caliber is the size of the bullet, not the length of the case.


Yeah, they said ".30 Carbine", not ".30 caliber".  .30 Carbine is, obviously, a very specific round that reasonably represents a transition from pistol to rifle round.  .30 caliber could be any range of things.


i can tell if you were agreeing with me or not. not wanting to get into a pissing match here. but the guy i quoted did say caliber.
Link Posted: 6/4/2010 7:03:26 AM EDT
Link Posted: 6/4/2010 7:26:12 AM EDT
[Last Edit: 6/4/2010 7:26:23 AM EDT by Zhukov]
Link Posted: 6/4/2010 7:37:22 AM EDT
Originally Posted By Eric802:
Agreeing.  


Link Posted: 6/4/2010 7:49:23 AM EDT
A friend has some LE interested in 357Sig uppers, especially since lowers with Glock magwells are available. The possibilities got the rusty wheels creaking a little.......

Looking at the performance numbers in quickload got me thinking that the Sig may defeat common vests at the increased velocities a 16" barrel makes possible (around 2,000fps). Realizing many agencies are going to .223 SBRs got me wondering if the .223 would defeat a vest at the slower velocities (around 2,000fps in a 7.5"). The .355 obviously has much more frontal area than the .224, which I'm sure has some bearing on the performance. I am asuming LE is going to ARs to defeat Kevlar.

A LE friend just gave me a retired IIIA vest, & I ordered some Factory Corbon 115g to try it out myself. Should be fun, if nothing else.
Link Posted: 6/4/2010 10:17:07 AM EDT
Originally Posted By pegleggreg:
A friend has some LE interested in 357Sig uppers, especially since lowers with Glock magwells are available. The possibilities got the rusty wheels creaking a little.......

Looking at the performance numbers in quickload got me thinking that the Sig may defeat common vests at the increased velocities a 16" barrel makes possible (around 2,000fps). Realizing many agencies are going to .223 SBRs got me wondering if the .223 would defeat a vest at the slower velocities (around 2,000fps in a 7.5"). The .355 obviously has much more frontal area than the .224, which I'm sure has some bearing on the performance. I am asuming LE is going to ARs to defeat Kevlar.

A LE friend just gave me a retired IIIA vest, & I ordered some Factory Corbon 115g to try it out myself. Should be fun, if nothing else.


Remember that you need to back the vest with something flexible but firm.  If you just hang the vest empty, everything will pass right through.
Link Posted: 6/4/2010 11:14:57 AM EDT
Originally Posted By securitysix:
Originally Posted By pegleggreg:
A friend has some LE interested in 357Sig uppers, especially since lowers with Glock magwells are available. The possibilities got the rusty wheels creaking a little.......

Looking at the performance numbers in quickload got me thinking that the Sig may defeat common vests at the increased velocities a 16" barrel makes possible (around 2,000fps). Realizing many agencies are going to .223 SBRs got me wondering if the .223 would defeat a vest at the slower velocities (around 2,000fps in a 7.5"). The .355 obviously has much more frontal area than the .224, which I'm sure has some bearing on the performance. I am asuming LE is going to ARs to defeat Kevlar.

A LE friend just gave me a retired IIIA vest, & I ordered some Factory Corbon 115g to try it out myself. Should be fun, if nothing else.
Remember that you need to back the vest with something flexible but firm.  If you just hang the vest empty, everything will pass right through.

Wow, thanks for the tip. I would never have expected that  & might have messed up the vest test.
I wonder what my mother in law is doing next weekend.............just kidding....
Link Posted: 6/4/2010 1:13:07 PM EDT
Originally Posted By pegleggreg:
Another thread got me thinking ........

If a .223 - 7.5"  AR is loaded with Hornady  75g  BTHPs  to 2,000fps it would generate about   700ftlbs of energy.

If a 357Sig 16.5" AR is loaded with Speer 115g Gold Dot's to 2,000fps it would generate about 1,000ftlbs of energy
(w/ max load of Power Pistol Powder)

Is the   .223   "rifle round"  now  going too  slow to penetrate a  std Kevlar vest?  (assume IIIA)
Is the 357Sig "pistol round" now going so fast it will  penetrate a std Kevlar vest? (assume IIIA)

How does all this work?
Projectile diameter must have some bearing on this, I guess.

More important is bullet configuration and construction. A pointed FMJ will penetrate better than a flat-nosed soft-point, for example.

I'm not sure about the 115gr Gold Dot, but I'd expect the .223 BTHP would punch through. I once fired MagSafe 9mm "New Jersey" load (ultralight bullet @ close to 2000 fps) at a double layer of Level IIA kevlar, and it cut through both layers like the proverbial hot knife in butter...
Link Posted: 6/4/2010 1:21:12 PM EDT
Originally Posted By thecreeper23:
The transition takes place at the .30 carbine.


This answer is exactly correct and, moreover, demonstrates how compromises suck.

Sam
Link Posted: 6/4/2010 1:26:10 PM EDT
Originally Posted By thecreeper23:
The transition takes place at the .30 carbine.

A lot of people like to call the .30 Carbine an "elongated pistol round." That's just plain wrong, though.

.30 Carbine was designed as a rifle cartridge, for the US Army's "light rifle" program which was initiated in mid-1940. It was derived from another rifle cartridge, the .32 Win SL.
Link Posted: 6/4/2010 1:53:00 PM EDT
Barrel length??

Link Posted: 6/4/2010 3:05:54 PM EDT
Originally Posted By pegleggreg:
Another thread got me thinking ........

If a .223 - 7.5"  AR is loaded with Hornady  75g  BTHPs  to 2,000fps it would generate about   700ftlbs of energy.

If a 357Sig 16.5" AR is loaded with Speer 115g Gold Dot's to 2,000fps it would generate about 1,000ftlbs of energy
(w/ max load of Power Pistol Powder)


Is the   .223   "rifle round"  now  going too  slow to penetrate a  std Kevlar vest?  (assume IIIA)
Is the 357Sig "pistol round" now going so fast it will  penetrate a std Kevlar vest? (assume IIIA)


How does all this work?
Projectile diameter must have some bearing on this, I guess.


The real problem with yer comparison, is it is apples to oranges.  the barrel lengths of the two are different, and therefor is not a fair comparison, the reason for a short barrel is for CQB manuverablity....u cant compare a 16" pistol cal carbine to a 7.5" rifle carbine.  Tho I would say this, if i were to pick a 7.5" carbine, I'd rather the pistol cal than the rifle cal.  The rifle doesnt have enough velocity to do any real damage other than 22 cal ice pick holes.  The pistol cal with a good HP round is designed to operate at pistol velocities.
Link Posted: 6/4/2010 3:26:51 PM EDT
Originally Posted By stanc:
Originally Posted By thecreeper23:
The transition takes place at the .30 carbine.

A lot of people like to call the .30 Carbine an "elongated pistol round." That's just plain wrong, though.

.30 Carbine was designed as a rifle cartridge, for the US Army's "light rifle" program which was initiated in mid-1940. It was derived from another rifle cartridge, the .32 Win SL.


All true; but the .30 carbine is perhaps at its best when chambered in an AMT longslide. THAT is a fun gun.
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