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MK 318 ammo Info 5.56

 
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  #29  
Old 10-02-2013, 09:47 PM
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Re: MK 318 ammo Info 5.56

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Originally Posted by Bastard TwoTwo View Post
Yeah, that's a part of it- for instance, the SOPMOD Mk18 MOD 0 was developed by Crane Division (Navy) for use by Special Ops units throughout the military (they don't just cater to SEALs is what I'm getting at). It's supposed to kinda bridge the gap between the M4/SOPMOD Mk1 and the M14/Mk14 DMR. It's basically an M4 with an AR15 upper- the barrel is 16". It was found during development by Crane that in the 16" barrel, a 1/10 twist is what they consider optimal balance between mid-distance accuracy (~500m) and terminal effect (i.e., the probability of tumble, bounce, etc.).

I also do know that the 1/7 twist rate of the XM16/M16/M16A1 was dropped sometime ago (in the '90's?) in favor of a 1/9. I did use an M61A2, which had been re-barreled at least once I should add, that had a 1/9 (it was engraved right on the barrel). What I don't know is whether that was the original twist rate of the M16A2, or if that barrel was added later as an upgrade, which the military does quite often, since it's cheaper than buying a whole new weapon system. I am quite positive that the 'A3 had a 1/9, and I know that the 'A4 I qualified with at Benning was a 1/9.

This is all, of course, presuming I haven't lost my marbles. These things happen.
Ya that sounds off to me, 1-7 is the standard for the m4/m16 family of weapons. Early on with the xm16/m16/m16A1 1-12 was the standard paired with the m885 round. When we switched to ss109, 62g 3mm steal penetrator in the 80s the standard became the 1-7 twist, in the m16/A2 and all of its fallow on variants. As for weapons from the SOPMOD program, I have no first hand knowledge of them at all.

The only other twist rates I am aware of are 1-8 that were issued on some DMR rifles for use with the MK262 round in both Army and Navy service. My MK18 was 1-7, 10.5 inch barrel. I shot lights out with 55g black hills sp ammo.

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  #30  
Old 10-02-2013, 10:13 PM
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Re: MK 318 ammo Info 5.56

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Originally Posted by ICANHITHIMMAN View Post
Gary

I have shook the hands of more Nam vets than any other era when I was in the service. You guys made us feel welcome over and over again. Thank you! Both my uncles served in your war, one with 5th group the other with the air force spreading agent orange, they died 3 years ago with in 6 month of each other.

I guess what I am saying is thank you!
I was sprayed with Agent Orange three times, and the powers to be said it was bug killer! I'd have never known if it wasn't for a buddy of mine who was out of A Troop 1st/1st Armored Cav. Now we got a list of over two hundred diseases linked to Agent Orange! Hell he was right at my back door! Brother in law was with B Troop, and he was between A Troop and me. He's already got signs, but think he's caught them in time. I think in the end it will have killed 50% of us, and the Fed will just sigh a relief! In time all these issues will be gone, and the U.S. Tax Payer well sigh a relief. But it was their baby from the start.

gary
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  #31  
Old 10-02-2013, 10:15 PM
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Re: MK 318 ammo Info 5.56

Know what I hate? Navy designations. Yours is a Mk18? Thought that was the 16" variant. Did I get it mixed with the Mk12 again? Yup. I did. My bad!!!

Mk12 Mod 0 is what I meant. That is the 16" pseudo-DMR M4 produced by the fine folks at Crane.

I was sooooo sure that 1/9 became the standard for the M16. Now I'm super compelled to research that. I know that single A2 that I used for all of 2 months before we "found" an M14 back in 2006 had "5.56NATO 1/9" [sic] (I forget the manufacturer- believe it or not, we use an interesting variety of replacement parts; the M16A4 I was issued in Basic Training had an FNH lower!)printed on the barrel.

Off to google I go....
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  #32  
Old 10-02-2013, 10:16 PM
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Re: MK 318 ammo Info 5.56

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Originally Posted by Bastard TwoTwo View Post
Believe it or not, that wasn't the only reason. In late '06, they added an additional 4th Battalion to every SF Group, which necessitated a new numbering system. I don't know how long they'll keep it that way before returning to the 3 Battalion format, if they ever return to it. It really was a headache trying to bridge the gap; one week the team number is (for instance) 095, and the next week it's 1054. Completely rearranged everything! Hated it.

For those uninitiated who may read this, the original Special Forces Team number format worked like this:

1, 3, 5, 7, and 0 (for 1st, 3rd, 5th, 7th, and 10th Groups) followed by

0-3 (A,B,C/1st Bn), 4-6 (A,B,C/2nd Bn), 7-9 (A,B,C/3rd Bn) followed by


0-9, designating the specific team within the previously established Company, Battalion, and Group.

So 3rd Team, B Company, 2nd Battalion, 1st Group is/was: ODA 153
and the only thing my guys worried about was where the safe house was
gary
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  #33  
Old 10-02-2013, 10:24 PM
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Re: MK 318 ammo Info 5.56

OK, found a TM dated 1998 that states that all 5 weapons systems in the M16 family have a 1/7 twist rate. Granted, they spell the word "riffling," but I'll try not to count that against whatever pentagon desk jockey typed it up. I'm gonna do further research to verify that it didn't change after 9/11. I'm pretty sure that I have a TM for the M4 on my shelf somewhere that may be dated like 2002 or something.

Thanks, ICANHITHIMMAN for pointing that out to me, and forcing me to double check myself. Life is so much easier when you're right, so I try to be as often as possible.
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  #34  
Old 10-02-2013, 10:32 PM
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Re: MK 318 ammo Info 5.56

Quote:
Originally Posted by Bastard TwoTwo View Post
Yeah, that's a part of it- for instance, the SOPMOD Mk18 MOD 0 was developed by Crane Division (Navy) for use by Special Ops units throughout the military (they don't just cater to SEALs is what I'm getting at). It's supposed to kinda bridge the gap between the M4/SOPMOD Mk1 and the M14/Mk14 DMR. It's basically an M4 with an AR15 upper- the barrel is 16". It was found during development by Crane that in the 16" barrel, a 1/10 twist is what they consider optimal balance between mid-distance accuracy (~500m) and terminal effect (i.e., the probability of tumble, bounce, etc.).

I also do know that the 1/7 twist rate of the XM16/M16/M16A1 was dropped sometime ago (in the '90's?) in favor of a 1/9. I did use an M61A2, which had been re-barreled at least once I should add, that had a 1/9 (it was engraved right on the barrel). What I don't know is whether that was the original twist rate of the M16A2, or if that barrel was added later as an upgrade, which the military does quite often, since it's cheaper than buying a whole new weapon system. I am quite positive that the 'A3 had a 1/9, and I know that the 'A4 I qualified with at Benning was a 1/9.

This is all, of course, presuming I haven't lost my marbles. These things happen.
I'm so old that I was issued an AR15 with the full auto selector. It had the short buffer and the light weight spring. No chrome anywhere. The frame even had the AR15 logo cast into it! The barrel was a 1:13 twist, and hits were ugly.
They changed the spring in Jan 68 to a much heavier one, and two weeks later changed the buffer to the long one as well. I never had a problem with the older setup, and it was what we called a "hummer." It shot that fast! A couple weeks later they changed the entire upper assembly with all the hard chromed stuff. The rifle seemed to be more accurate. Folks seemed to die just as quickly, and never gave it a second thought. Plus my main interest at the time was with the "hog." Two weeks later I wept
gary
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  #35  
Old 10-02-2013, 10:48 PM
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Re: MK 318 ammo Info 5.56

Alright, I can't find any evidence of the 1/7 twist rate changing. DID find that the specific reason for changing to the 6 groove, right hand 1/7 was to accommodate the SS109 NATO cartridge, which was apparently heavier than the Stoner test ammo and the M193, and yawed too much at a distance, so the Army decided on the 1/7 to tighten up the groupings. At any rate, my apologies to all for the incorrect info!

You had a CAR, didn't you, Gary? I've seen some pictures of those- I went most of my life not even realizing that the Army had a carbine in circulation that early. I think they're neat.

As a collector, I'd LOVE to own an XM16E1, a CAR15, an M16A1, A2... Heck, even the C7 an C8 rifles used by Canada and the UK.

As a New York State Citizen, I can't technically *legally* buy any of those right now. I hate Cuomo.
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