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Posted: 9/15/2004 5:52:12 PM EDT
[#1]
some people will tell ya the speed will be in the 50 fps spitball range
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Posted: 9/15/2004 5:52:44 PM EDT
[#2]
Fragmentation range? Zero. And that's only because it can't be a negative number. M193 typically gives muzzle velocities around 2200-2300 fps from a 7.5" barrel, and there is NO 5.56 ammo that will perform well enough for defensive use at those velocities. You essentially have a large, loud "pistol" with the terminal performance of a .22LR. Yes, it can kill, and with a very lucky shot, it might even give near-instant incapacitation (true also of a .22LR pistol), but the chances are very high that it could fail to stop a motivated attacker before that person could kill you. That's bad, m'kay?
-Troy |
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Posted: 9/15/2004 6:03:23 PM EDT
[#3]
Thanks for the info gents. I was afraid of that. From the data I've found, a 10.5" bbl won't do that much better (2700 FPS MV) and an 11.5" bbl will be in the 2800 FPS range. Seems like once you get into the 11.5" bbl, it's a pretty big pistol.
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Posted: 9/15/2004 10:23:50 PM EDT
[#4]
At least with a 10.5" or longer barrel, you can use Mk262 ammo and get good performance out to 20 yards or so. Of course, Mk262 isn't easy to find and costs a lot more than M193, plus you need a 1:7 barrel.
The only way true AR pistols make any sense to me is with a pistol caliber, such as a 9mm upper, as 8" is about the ideal barrel length to maximize performance from most pistol rounds. -Troy |
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Posted: 9/16/2004 5:47:17 AM EDT
[#5]
My actual measured results with reloads were even less impressive. Loads that nominally produce 3000 to 3100 fps in 20 inch barrels often lost 600 fps in my 10 incher. 2200 fps was a typical average velocity using 55's, but I did not chrony any full m193 spec loads. Using 69's, a load speced for around 2700 fps chronied at 2225 fps, but had an outstanding ave. dev. of only 17 fps! This was a MAX load in the manual, BTW. Energy wise, you are looking at around 700 to 750 ft.lbs. of energy at the muzzle, LESS THAN A 44 MAGNUM handgun... Paladin |
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Posted: 9/16/2004 5:32:52 PM EDT
[#6]
I had an avg of 2382 with 3131A from my 7.5" DPMS. It was fairly warm dry sunshine day. Used a cheap green "Chrony".
Santa-Barbara SS-109 went 2340. From my 11.5" Bushnaster 1x9 barrel, 3131A ran about 2785, SB ss-109 went 2690 From the std 20" 1x7 Colt barrel, 3234 (3131A) and 3096 (SS-109) |
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Posted: 10/14/2004 6:38:19 PM EDT
[#7]
Sorry to bring this thing to life. Are these things really THAT bad for defensive use? I'm considering doing a 7.5" for home defense. I mean, people are raving about FN's P90. How do the ballistics differ from that? What about using hollow points to aid in fragmentation? I can't believe it would be worse than 9mm!? |
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Posted: 10/14/2004 8:10:38 PM EDT
[#8]
How about a ballistic tip? not much penitration, but lots of surface dammage (probally not the home defence round either)
BRM |
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Posted: 10/14/2004 8:23:14 PM EDT
[#9]
The 5.56 is designed for rifles. The FN 5.7 is designed for pistols and short barreled SMGs. Don't even consider an AR pistol a good gun for self defense.
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Posted: 10/14/2004 9:22:36 PM EDT
[#10]
...but turns in horrible terminal ballistics anyway. -Troy |
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Posted: 10/15/2004 5:32:12 AM EDT
[#11]
Noone raves about thte P90... everyone says it sucks.
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Posted: 10/15/2004 6:32:52 PM EDT
[#12]
So 9mm HPs, say out of a MP5, would be better than a SBR 5.56? Still seems counterintuitive... |
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Posted: 10/15/2004 6:37:25 PM EDT
[#13]
In any scenario except those which involve the bad guys wearing body armor, yes.
Why? 5.56 was originally adopted because it was shown that small caliber, high velocity bullets could be effective at short/medium ranges. It was developed to be used out of 20" barrels in order to get that needed velocity. Chop 13" off that barrel, and you've robbed the bullet of so much velocity that it no longer does the job. It's not that difficult a concept. -Troy |
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Posted: 10/15/2004 7:35:03 PM EDT
[#14]
I have taken my 7.5" and punched holes clean through a steel wheel at 50yd with a moderate handload of H-322 and a Speer 55gr SP. I don't think body armor is going to be an issue.
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Posted: 10/15/2004 9:03:08 PM EDT
[#15]
Me neither, but it would be for an MP5. That's why I clearly stated that the ONLY scenario where an AR pistol beats the MP5 is if body armor is involved. -Troy |
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Posted: 10/16/2004 4:43:49 AM EDT
[#16]
I've watched a guy fire the Oly AR pistol. There is a MASSIVE muzzle flash. Reason?....the round needs a longer barrel to complete the burn of most of the powder. The whole concept of this weapon is silly. For home defense or QCB, I don't want a stupid AR pistol. Pull out a real AR for that fight.
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Posted: 10/17/2004 6:37:14 PM EDT
[#17]
Gonna play devils advocate here...
Has there been any actual tests of ballistics using HP defensive rounds, like TAP, etc. out of SBR .223's like 7.5-10.5"??? I would think HP's coming at you at 2000+ FPS would still penetrate enough to hit vital organs, due to the high velocity. I mean, everyone uses HP's w/ pistol calibers and they are much slower than .223. Why would ,223 only do "surface damage"? Doesn't make sense. What about 77gr loads? Thanks, really trying to justify the $200 tax stamp  |
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Posted: 10/17/2004 6:47:25 PM EDT
[#18]
You are a moderator and you are asking newbie questions like that? For shame, for shame.... read the ammo oracle!
All ballistic tips and hollow points underpenetrate from all barrels in 5.56mm and the 75 and 77 grain run out of steam at 50m or under in a 10.5" barrel... though this would be OK for a dedicated indoor weapon if you had hearing protection on. 7.5" and 75 and 77 grain ammo has not been put in the jello to my knowledge. Perhaps someone knows better than I but I would assum a zero fragmenting range as the bullets will be below the frgmenting velocity floor. |
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Posted: 10/17/2004 7:02:15 PM EDT
[#19]
I'm the fitness/self defense mod  I've read it, but didn't find my answer specifically, i.e. pistol HP vs. .223HP, whats the difference? |
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Posted: 10/17/2004 11:04:54 PM EDT
[#20]
Pistol hollow point perform like rifle soft points and simply expand. Rifle hollowpoints fragment into such small pieces they have too little momuntum to travel further than 6" or so deep into tissue. Arms and odd angles and mags stored on the chest will prevent the fragments from reaching vital organs. Also there is some testing which shows bad penetration through body armor on lightweight ballistic tips... that is to say they penetratre but penetrate very shallow. Pistol hollow points stay in one piece and have the momuntum to travel very far in tissue. That is the difference.
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Posted: 10/17/2004 11:08:24 PM EDT
[#21]
Pistol caliber 7.5. That would be very cool. 10mm or .45 Super maybe.
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Posted: 10/17/2004 11:40:35 PM EDT
[#22]
Just get a 9mm upper...
Who needs an MP5k when you can have an AR PDW ... 9mm out of a 7.5" barrel would be VERY effective... Use the oly upper -> mags for cheap (STEN mags) |
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Posted: 10/18/2004 5:24:41 AM EDT
[#23]
Interesting. I'll have to look into the pistol cals. |
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