MK 318 ammo Info 5.56

[ICANHITHIMMAN]

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.

 

[Trickymissfit]

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

 

[Bastard TwoTwo]

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....

 

[Trickymissfit]

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

 

[Bastard TwoTwo]

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.

 

[Trickymissfit]

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

 

[Bastard TwoTwo]

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.

 

[ICANHITHIMMAN]

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

My mother told me when her brother came home he had sores all over his body from the stuff. Horrible, just horrible stuff

 

[ICANHITHIMMAN]

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.

LOL ya it sucks! We are still fighting though man still fighting!

 

[ICANHITHIMMAN]

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....

MK12 most likely did have a 1-9 barrel and was built off an A1 lower. FN makes all the A2,A2,A4 variants and colt the M4. However Remington was awarded contract for some M4 a few years back now that the Army owns the rights to the weapons system. If we got into Air force small arms the skys the limit, they are the only ones who are frugal at all.

 

[Bastard TwoTwo]

Yeah, I was just shocked- when I arrived at Basic, and they issued rifles on day 2, most of my platoon mates had Colt lowers, some had Olympic, I had an FNH.... I was of the impression prior to this that Colt and KAC were the ONLY companies that the US Army contracted with for M16/M4 weapon systems, so seeing what were probably replacement parts from another company was a surprise. Then shortly after that, Colt's patent expired and the Army went looking at possible replacements- that's when EVERYBODY started showing up with an AR design.

My unit was issued the RSASS in '07, speaking of Remington. Our snipers thought it was trash. We left them in the arms room at home and they took the M24's instead. Bolt action .300WM beats semi-auto .308 any day of the week.... BUT, I did have an appreciation for the Mk14EBR personally. It wasn't a 1000m tack driver, but it's better than the RSASS, more compact, and more flexible in an urban environment. Worked great in places like Baqubah.

On a note related to Gary's Agent Orange, our generation has the burn pits; lot of respiratory issues coming up, and other things will likely crop up in the next decade or so. We were burning refrigerators, tires, you name it- you KNOW that stuff can't be good for us.

 

[Trickymissfit]

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.

Believe it or not, I can remember three different CAR's. There was the one we normally think of with about a 12" barrel and the regular bird cage suppressor (might have been a 13" barrel). There was one that had a slightly shorter barrel with a little different suppressor, and then there was one with a short barrel that was about ten inches long. It had a long flash suppressor that looked like a miniature M14 flash suppressor. I had the middle one for awhile, and the gun was always messing up. Unburnt powder getting into he locking lugs was the problem. Plus one never wants a rifle that looks different! I preferred the standard M16. When we did an insertion, I would wrap the rifle and three bandoliers of 20 round mags inside two pill bags. These were held with shoe laces and a little black tape. Then after I put my ruck sack on, Randy or Top would strap it on my back just under the asbestos glove. I hated the CAR 15! SF teams used them a lot, but half still used basic M16's. Believe me these guys had their choice of any and everything out there. But never saw any SF guy carrying an AK47. I've seen them use everything from High Standard 22 short pistols to the oddest looking Browning 50 Cal I've ever seen. Even back then there was a constant rumor that the Army was working on a .277 version of the M16, but nothing ever materialized. I do know they did a lot of work with the 5.56 necked up to 6mm, and using an 85 grain bullet. In that theater we needed 100 yard knock down power, or something that would give a chest hit that lasted forever almost instantly. Even the 7.62x51 didn't offer that, as the round usually just blew right thru them. Still if the guy had a chest pack on it would often flip him. That new bullet may help to bridge that gap, but I think a 25 caliber bullet (ala Copper Head) weighing about 85 grains might be a better solution. Or maybe something like the 6.5TCU with a 100 grain bullet. The round works well in a 15" barrel, and will get around 2500 fps. Now I never shot anybody that got back up, but I always put three to four rounds in him. I was taught to think "adams apple", and they always said that if his fingers were moving, then shoot him again. I'm alive and well, so somebody knew his business.

My original First Sargent was a border line idiot, and entered the combat zone on his first over seas tour. He nearly got me tagged five times in one week out on an LP, and I just wanted to frag him. But he went home right in the middle of Tet, and we got a hard nosed crusty guy that was an old man of about 37 years of age. He actually earned his diamonds in Korea! Was part of that bunch that MacArthur left behind on the Yalu River to hold off a gazillion Chinese. Like I said he was tough, and was probably the original prepper. First thing he did was to blow up that LP, and I was endeared to him for life. He took me all over the place, and the two of us nearly bought the farm more than once. He would survey the arena after the fact, and show us why things went wrong over here and right over there. Hated the M16! Saw him carry everything from an M2 carbine to a grease gun, but always took an M16 on insertions after our third or fourth trip. He probably humped a 140lb load everytime. He told that after Korea, he was never gonna run out of ammo and water again! He was serious about that. Had little if any use for butter bars, and you'd best have a hash mark on your sleeve, or you were rated right with the Privates. Ten months later I lost him (he did make a full recovery), and got a really nice black fellow that seemed to know his business. But not as good as Honeycutt. He went home, and we got a fourth one. I held him in suspect till I saw him earn a Silver Star on a howitzer. I see him once a year, and he's getting pretty frail now. That howitzer crew was KIA, and he scrounged up a 1st Lt, and somebody else to shoot. Then a kid showed up outta nowhere that was from the motor pool. They then showed the kid how to set fuses and cut powder. And shot WP with the minimum charge and time inside the perimeter. I seriously gained respect for him and the LT. The LT was shooting with his arm tied off. The third guy had two or three holes in him. Then a Sea Bee showed up, and actually asked what he could do (he'd been stranded out there for two or three days). He said he knew how to shoot that fifty sitting above and behind them. He died on that gun. The kid from the motor pool was opened up like a can opener from a rocket. He got his Silver Star in 2012. The Sea Bee has been put in for one as well. I learned a lot from that. Most everybody will step up if given the chance. They did an aerial recon around that base camp and counted 1100 bodies from the air. It ended up being close to 2,000 confirmed dead. But they never got past that little base camp!
gary

 

[ICANHITHIMMAN]

Yeah, I was just shocked- when I arrived at Basic, and they issued rifles on day 2, most of my platoon mates had Colt lowers, some had Olympic, I had an FNH.... I was of the impression prior to this that Colt and KAC were the ONLY companies that the US Army contracted with for M16/M4 weapon systems, so seeing what were probably replacement parts from another company was a surprise. Then shortly after that, Colt's patent expired and the Army went looking at possible replacements- that's when EVERYBODY started showing up with an AR design.

My unit was issued the RSASS in '07, speaking of Remington. Our snipers thought it was trash. We left them in the arms room at home and they took the M24's instead. Bolt action .300WM beats semi-auto .308 any day of the week.... BUT, I did have an appreciation for the Mk14EBR personally. It wasn't a 1000m tack driver, but it's better than the RSASS, more compact, and more flexible in an urban environment. Worked great in places like Baqubah.

On a note related to Gary's Agent Orange, our generation has the burn pits; lot of respiratory issues coming up, and other things will likely crop up in the next decade or so. We were burning refrigerators, tires, you name it- you KNOW that stuff can't be good for us.

That seams very out of sorts, never seen an m16 in the Army that was not a FN and never ever an Olympic that never happened. FN makes the M16, M249, M240 for US military, Colt makes the M4. Knights only ever made the SR25 and the M110.

 

[Bastard TwoTwo]

KAC doesn't make the complete rifles (actually not even on the SR25 anymore, as it has been replaced by the RSASS), but what they do is make the rail systems, and EVERY variant of the M16/M4 that I have used that had an issued rail system had a KAC rail system. Colt made the majority of the M16's after Armalite got absorbed, or whatever the hell happened in the '60s that gave Colt control over the patents and whatnot. Now I'll admit that I cannot 100% identify *Olympic* as the lower used, but I know it wasn't an FN lower, and it wasn't a Colt lower.

And YES, my bunkmate in Basic had a *Colt* M16A4; I remember it quite distinctly, as we hung our rifles on the end of the bed, mine on one side, his on the other- I got a good look at it every night for 15 weeks; the rampant stallion design is usually a dead giveaway.

I'm just sayin' that I was surprised that Colt wasn't the only arms supplier to the US Army (at the time, I think wasn't even aware that the M249 was an FN design- learned that during Basic). I was 19, and NEW.... Got to Bragg later on and dehydrated myself, I drooled so much. Ever look at a JSOC arms room? Those jokers have EVERYTHING. Name a battle rifle. They have like 10. Going out on a deployment? They don't have the weapon in that specific arms room that you want? They'll call around and find another SF Arms room that does.

I think I fainted that first day.