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Page AR-15 » AR-15 / M-16 Retro Forum
AR Sponsor: bravocompany
Posted: 10/21/2014 6:01:48 PM EDT
Original factory? Know where there's two barrels with fsb pin grooves closer together and the barrels are said to be 18 inches. These ever used in production?
Link Posted: 10/21/2014 6:31:39 PM EDT
[#1]
Only 18" issue rifles I know are special 18" SDMR (Squad Designated Marksman Rifle) issued back in 2006ish to correct shortcomings of 14.5" M4s in the desert.  I don'rt think Colt made them, but rather the AMTU armory at Ft. Benning, GA.
Link Posted: 10/21/2014 7:16:32 PM EDT
[#2]
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Quoted:
Only 18" issue rifles I know are special 18" SDMR (Squad Designated Marksman Rifle) issued back in 2006ish to correct shortcomings of 14.5" M4s in the desert.  I don'rt think Colt made them, but rather the AMTU armory at Ft. Benning, GA.
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Wasn't Knight's Armament supplying the Military with the 18" SPR's and SDMR's?
Link Posted: 10/21/2014 8:39:08 PM EDT
[#3]
Cool, but these c don't have extensions so would that make 2 inches difference?
Link Posted: 10/21/2014 9:24:45 PM EDT
[#4]
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Quoted:
Cool, but these c don't have extensions so would that make 2 inches difference?
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In order to install them you need barrel extensions, they are probably 20's with no barrel extensions.
Link Posted: 10/22/2014 10:36:55 AM EDT
[#5]
MK 12 SPR was built by Crane Ind.

MK 18 SPR currently issued by Daniel Defense earlier MK 18 was just shorten M4 with bigger gas ports.
The MK 18 was mainly used for Close Quarters like on ships. Extra velocity was not a issue.




Use what “THEY” use.  The Daniel Defense MK18 features the railed forend Daniel Defense currently provides to USSOCOM and a 10.3” Cold Hammer Forged Barrel.  The Flat Dark Earth MK18 rail system features the Bolt-Up System and has been rigorously tested prior to fielding by USSOCOM (currently over 15,000 units).  The 10.3” barrel is the same length in use for the MK18 upper most commonly used for CQB operations.  The MK18 Factory SBR by Daniel Defense is unmatched in size, weight, and performance. This rifle also comes with the newly designed, rugged and comfortable Daniel Defense Buttstock and Pistol Grip.


Link Posted: 10/22/2014 10:41:21 AM EDT
[#6]
Actually 3.5" difference.  The standard M4 has a 14.6 inch barrel.  That extra 3.5" can give another 200+ fps, which translates into greater range.  I believe the SDMR uses the Black Hills MK262 Mod1 77 grain OTM.  VERY nasty and lethal, even at reduced velocity and distance.
Link Posted: 10/22/2014 12:55:14 PM EDT
[#7]
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Quoted:
Cool, but these c don't have extensions so would that make 2 inches difference?
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if these barrels have had a fsb or gas block already installed, and then had the extensions removed, it will probably cost more to get new extensions properly timed and headspaced than what they're worth
Link Posted: 10/22/2014 1:52:24 PM EDT
[#8]
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Quoted:


if these barrels have had a fsb or gas block already installed, and then had the extensions removed, it will probably cost more to get new extensions properly timed and headspaced than what they're worth
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Quoted:
Quoted:
Cool, but these c don't have extensions so would that make 2 inches difference?


if these barrels have had a fsb or gas block already installed, and then had the extensions removed, it will probably cost more to get new extensions properly timed and headspaced than what they're worth



Yeah, that was my fear, thanks for tge heads up on this.  I'll pass on em.....



Link Posted: 10/22/2014 4:05:26 PM EDT
[#9]
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Quoted:



Yeah, that was my fear, thanks for tge heads up on this.  I'll pass on em.....



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Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
Quoted:
Cool, but these c don't have extensions so would that make 2 inches difference?


if these barrels have had a fsb or gas block already installed, and then had the extensions removed, it will probably cost more to get new extensions properly timed and headspaced than what they're worth



Yeah, that was my fear, thanks for tge heads up on this.  I'll pass on em.....





or if cheap enough, they could make .22 barrels outta them
Link Posted: 10/22/2014 5:06:30 PM EDT
[#10]
What was weird to me was the spacing of pins for fsb on the 18 inch barrels.5
Link Posted: 10/22/2014 5:15:54 PM EDT
[#11]
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Quoted:
What was weird to me was the spacing of pins for fsb on the 18 inch barrels.5
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any markings on these barrels?

could be someone did  proprietary gas blocks or prototype fsb's on 'em
Link Posted: 10/22/2014 5:17:53 PM EDT
[#12]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Only 18" issue rifles I know are special 18" SDMR (Squad Designated Marksman Rifle) issued back in 2006ish to correct shortcomings of 14.5" M4s in the desert.  I don'rt think Colt made them, but rather the AMTU armory at Ft. Benning, GA.
View Quote

SDMR is 20".
Link Posted: 10/22/2014 5:18:22 PM EDT
[#13]
Discussion ForumsJump to Quoted PostQuote History
Quoted:

Wasn't Knight's Armament supplying the Military with the 18" SPR's and SDMR's?
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
Only 18" issue rifles I know are special 18" SDMR (Squad Designated Marksman Rifle) issued back in 2006ish to correct shortcomings of 14.5" M4s in the desert.  I don'rt think Colt made them, but rather the AMTU armory at Ft. Benning, GA.

Wasn't Knight's Armament supplying the Military with the 18" SPR's and SDMR's?


No. Crane made the SPRs and AMU the SDMRs. They tended to have Knights parts on and in them though.
Link Posted: 10/22/2014 5:36:44 PM EDT
[#14]
Might need to ask the guy more about these.

Page AR-15 » AR-15 / M-16 Retro Forum
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