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Posted: 12/9/2003 11:22:44 AM EDT
I was thinking of building an 11.5" SBR just for SHTF/urban type use. Before I go through the hassel of the $200 tax and FEDERAL registration, I was wondering what type of performance hit I would be taking on an 11.5" upper? Obviously, there is one. Am I sacrificing SO MUCH muzzle velocity that I am making the 5.56 impotent? If not, what is the effective range of an 11.5" barrel, in both accuracy and effective muzzle velocity?

Thanks!
Link Posted: 12/9/2003 11:30:43 AM EDT
Originally Posted By thompsondd: I was thinking of building an 11.5" SBR just for SHTF/urban type use. Before I go through the hassel of the $200 tax and [i] FEDERAL registration[/i], I was wondering what type of performance hit I would be taking on an 11.5" upper? Obviously, there is one. Am I sacrificing SO MUCH muzzle velocity that I am making the 5.56 impotent? If not, what is the effective range of an 11.5" barrel, in both accuracy and effective muzzle velocity? Thanks!
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If you use M193 you'll probably be ok as far as getting out a bit further. I can't say that is fact cuz I don't know myself for sure. The other thing is to use the BH 68gr BTHP or 75gr BTHP. Those will fragment at lower velocities than M193 and M855. Thats my understanding at least from all the info floating around on the ammo board. I'm sure someone else can help ya out better than I can. I'm going to go through the SBR thing as well but i'm keeping my 14.5in barrel and just really doing it so that I can chopp my pistol cal upper down.
Link Posted: 12/9/2003 12:20:41 PM EDT
[Last Edit: 12/9/2003 12:22:09 PM EDT by thompsondd]
That raises another interesting question: best ammo and twist rate for an 11.5" barrel? Should I stay with the 1/9? I normally only shoot the M193 55gr stuff (either XM193 or Q3131A). I tried some of the IMI 62gr M855 out of an MT6700 20" 1/9 HBAR awhile back. I don't have the MT6700 anymore and the M855 stuff is just too expen$$ive (IMHO) compared to the M193. Right now, my main stay is the M193 (either XM193 or Q3131A) from a 16" 1/9 HBAR on an M4gery. I haven't shot any of the heavier 69, 75, or 77gr stuff before.
Link Posted: 12/9/2003 2:39:13 PM EDT
I think you'll want to go 55grn and heavier before you go lighter through an SBR, so I'd go 1:7 to keep your options open. The best most reliable shorty uppers IMO are the LMT 10.5's from MSTN. Search some threads to hear their gospel. If you ever go full auto they're one of the few that run 100% straight out of the box. Crappy reliability has given shorties bad names more than velocity loss. Accuracy is also fantastic from the LMTs. For indoor/close work (<100m) I'm sure it would be more than adequate velocity-wise, and as handy as a sub. Go for it!
Link Posted: 12/9/2003 3:34:35 PM EDT
[Last Edit: 12/9/2003 3:38:12 PM EDT by AR-10]
[url]http://www.ammo-oracle.com/#fragrange[/url] Not sure if this link will take you right to the table showing different barrel length/velocities, or if you will have to scroll down to find it. Bottom line is an 11 1/2 inch barrel will cause M193 to fragment out to about 40-45 meters. Acuracy should not be any different from that of a 16" or 20" barrel.
Link Posted: 12/9/2003 4:08:14 PM EDT
Thank you to everyone who has replied. I am having some SERIOUS second thoughts. I knew that if I did build and 11.5" SBR that its use would be limited to urban/CQB only. But 40-45 meters before I hit 2700fps (the minimual velocity that M193 will fragment at) really makes me rethink my plans. Of course, using a heavy bullet that would still fragment at velocities less than 2700fps is an option that makes the 11.5" still viable, but I would have to buy/stock another type ammo. I am trying to keep the types of ammo that I stockpile down to a minimum (have stayed away from AK47 and AK74 for this reason only), but it is looking unlikely that I can hold on to that pipedream much longer.
Link Posted: 12/9/2003 4:24:44 PM EDT
Link Posted: 12/9/2003 7:24:26 PM EDT
Wes from MSTN posted that he some very nice groups at 100 yards with one of his awesome LMT 10.5" uppers.
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