MK 262 Mod 1, 5.56MM 77 info


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1lostinspace
October 27, 2007, 12:15 PM
Has anyone pulled the bullet and measured the powder?
I was told it has 24.gr TAC in it but that might have been for MOD 0
Does anyone have info on that?

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45ACPUSER
October 27, 2007, 01:46 PM
Never guess what powder it is. Plus you have to realize that BHA uses non-canister grade of powder for their loading. They also used brass with crimped primers.

Your only safe route is to work up the load yourself watching for pressure and measuring velocity by way of a chrono.

Prudent people follow proper technique for developing a load, not trying to guess what powder a factory uses!

1lostinspace
October 27, 2007, 01:54 PM
oh yeah thanks for the info that solves my problem:scrutiny:

snuffy
October 27, 2007, 02:37 PM
What part of " you can't pull bullets from factory ammo to see how much and what type of powder is in them" don't you understand?

See my post in "combat 5.56mm loads part 2".

1911user
October 27, 2007, 06:08 PM
Factory loads are just that. You do not have access to the powder to duplicate factory loads exactly. You can choose a close starting point and work up loads that may be very close to the same velocity using a similar bullet. Watch for pressure signs; real Mk 262 is loaded to nato-spec pressure. Newer reloaders have no business loading ammo that hot IMO. Also, the cannelured 77gr HPBT of Mk 262 rounds are not stock items from Nosler (mod 0 ammo) or Sierra (mod 1 ammo). Nosler did sell a small supply of the bullets but that was over a year ago and they're long gone now.

1lostinspace
October 28, 2007, 12:38 AM
you can get MOD 1 bullets at midway I just bought 500 rounds.

Does anyone know how many fps I should be getting out of a 16" in order to duplicate mod 1?

45ACPUSER
October 28, 2007, 12:57 AM
You have to have chrono to know how fast your loads are going. And, if you want to replicate a load then do more research on load specs. I best offer up the Ammo Oracle on AR15.com

oh yeah thanks for the info that solves my problem You do not need to be smart ass when some is trying to help you. A lot of noob reloaders think they can duplicate load with off the shelf components, and that is simply impossible!

IE guessing what powder is used? Ha Ha Ha good luck, because you simply can not get the powder they use. Powders are blended for factories to use to meet their specs. Hence the term non-canister powder!

This article ought to help the OP understand a bit more, but it still does not change the fact that the OP has to work up the load carefullyl. There is no sense to copy cat reloading that would be an unsafe thing to do. What is safe in one gun might not be in yours!
http://www.gunsandammomag.com/ammunition/mk262_080105/index.html

Sunray
October 28, 2007, 01:27 AM
"...you can get MOD 1 bullets at Midway..." The Mod 1 ammo supposedly uses 77 grain Sierra Matchkings with a cannelure so it'll work reliably in MG's. (Why you would need a match grade bullet for an MG is beyond my pay scale though. They are talking 600 to 800 meter accuracy though.) You can get them any place that sells Sierra bullets.
Aside from not being available, ammo manufacturers don't advertise the type or amount of powder they use in any of their ammo. As long as they get the velocities and accuracy they want it can change from lot to lot.
Work up a load for 77 grain bullets. I'd be using IMR4064 or Varget. Hodgdon's site has lots of loads for that bullet weight.

goon
October 28, 2007, 02:16 AM
And as someone else above stated, if you are a new reloader please be careful working with loads approaching the maximum.
Before you chamber a round in your $900 AR and prepare to fire it about 4" away from your face, ask yourself if the threat of blindness, death, paralysis, and blowing a nice rifle to peices is really worth that extra 50 fps and the 10 yards of fragmentation that may come with it.
This kind of thinking just adds a little extra margin of safety to something that can never have too much safety. You just don't gain enough with most max loads to really make it worth it. Save that extra grain of powder and the wear it will put on your rifle.
Just my $.02.

ftierson
October 28, 2007, 02:59 AM
The original M262 was designed to put some lethality back into the shortbarreled rifles like the M4 (with a 14 or so inch barrel)...

The original rounds were designed for special (non-normal military) barrels for the 10th SF in 1/9 twist and were designed to keep the bullet stable out to slightly over 300m out of the 1/9 short barrels in the temps experienced in the Iraq and Afghanistan areas of operation.

The current 1/7 M4 will stabilize the bullet out much farther.

As many have mentioned, pulling the bullet of M262 Mod 0 or 1 rounds and weighing the powder charge will only tell you how much powder is in that round.

Any load workup should involve the use of a chronograph coupled with an understanding of the round that you're trying to duplicate and extremely good load information. Keep in mind that even canister powders labeled for sale to reloaders vary somewhat in burning rates and pressure curves, so exercise care when attempting to duplicate any factory produced ammo. Also keep in mind that there may be no canister powder available to reloaders that duplicates the one that factory ammo uses...

Stay safe...

Forrest

Don't Tread On Me
October 28, 2007, 01:30 PM
The NATO 77gr load is very hot. I wouldn't load to that spec. Add heat from rapid fire, and maybe a 90 degree day in the summer and pressures ramp up quick on an already hot load.

It does about 2,848fps out of a 20" barrel. Most SAAMI data tops out in the 2,700 range.

Regardless, any load at or around 2,800 with a 77gr bullet is beating up the brass. I wouldn't call it a dangerous load, but definitely hot. You can see it in the primers. They begin to flatten. They definitely look different than primers from a SAAMI load. Ignore these Highpower nutjobs who load 75gr+ bullets at nearly 3,000fps. Some have gotten kabooms in the summer with a load that worked in winter. There's no room for any amount of bullet setback. Just too many variables.

Just not worth it. Load to a lower speed and you'll be fine. Loading past 2,800 to get a few more yards of "terminal performance" ?? Just the fact that it is a 77gr bullet makes it more effective than military ball at ALL ranges. Hornady TAP FPD is loaded in the 2,650fps range, and there's no doubt that it's effective and safe. This is one of those "be happy with what you've got" type of things in my opinion. You get superior effectiveness, more range and more accuracy. Even without the extra NATO fps.


I really like TAC. Good powder. It is very, very, very clean burning powder. When they say 2 patches and clean, they aren't kidding. A shooting session with TAC is like shooting literally 50% of the volume with a different load or factory ammo in terms of barrel and action filth afterward. It is also more speed appropriate for the mid to heavy .223 bullets out of 16-20" barrels.




Ah, quick story. Was thinking about making a thread about it but haven't gotten around to searching the forum to see if it hasn't been posted already.


THIS IS WHY YOU DO NOT LOAD OVER MAX:

For one, the military uses huge lots of primers that get tested in advance. Keep that in mind as I tell this quick story.


Bought some CCI BR4's.

I would shoot strings, and out of the blue - I'd have 1 shot go 200-220fps faster. Started scratching my head. Thinking....bullet setback? So I was feeding this into the chamber by hand and closing the bolt behind it and then tapping the forward assist. Same thing. HMmmm? Could be be my weight? Scale messed up? Nope. I have a check-weight set and the scale gets checked every use and has never been more than .1gr off at any weight. Each charge is weighed by hand during work-ups and I have never had that kind of an anomaly before.

Turned out it happened a couple more times and I called it quits as I was on my mid-range charge. Didn't want to risk it.

Then, earlier this year in an issue of Handloader magazine, the author was doing a .223 primer test for accuracy. See if there's any practical difference between the various primers. Sure enough, he came across the same problem and was puzzled by it. He would get 1 shot out of a 5 shot string go 200fps faster. Ruining groups and killing the ES/SD of a load. Not to mention, being unsafe.


Haven't heard anything about that since. But that happened with the CCI BR4. I wonder if a defective lot had been released? No primer should have that kind of fluctuation out of no where. I need to dig up the article and scan it.


Anyway, that's my story. Now, imagine loading that 77gr load to over 2,800fps. Add in a hot barrel from a shooting session, add in a hot day ...come across a primer like that giving you 200fps. Add it all together and you've got a load that could be 350fps hotter or more. KABOOM! I know a hot day and a hot barrel can add 100fps from all my chronographing. That alone is reason to stay at SAAMI max or a touch lower. Let along a freak defective primer, a slight bullet setback or some other factor adding dangerous pressures.


Always build in some safety in your loads. Because it isn't a perfect world. The military does insane amounts of testing on their components. They force their suppliers to do real world large volume batch testing of everything. Also, all their rifles are proof-load tested then MPI tested, they also use the strongest gun barrel steel and have big sloppy chambers.


FPS isn't everything. Hits count. Badguy isn't going to care when he gets smacked downrange by a 77gr Nosler whether it is doing 2,400fps or 2,475fps. And if this is for competition, these hot loads are absolutely not the most accurate.



Proceed with caution. Your eyes/face/fingers/life isn't worth a few fps.

1lostinspace
October 29, 2007, 11:54 AM
You guys are right here is what I came up with 25 grain varget 75 gr bthp hornady I have reloaded 2000+ of that and have never had a problem it gives me about 2700 fps out of a 16". I have not figured out what to do with the 77 I was thinking 24-24.5 TAC you guys are right about blowing things up for just a few fps and I thought that mk 262 mod 1 used TAC. So there for if you pull it you can measure how much is in there. I guess it's a different kind of powder.

goon
October 29, 2007, 02:11 PM
Yep. Some companies do supply loading data for their bullets though to help you approximate factory loads. I know that Winchester used to because they sent me a manual once and I still use it alot with their bulk bullets. I don't know if others do that or not.

1911user
November 2, 2007, 09:13 PM
http://www.ar15.com/forums/topic.html?b=1&f=9&t=635020

This thread is worth reading especially for the pressure chart results showing what happens when factory mark 262 mod 1 ammo gets hot before firing.

I'd feel safer loading 9m +P+ ammo using worn out brass than trying to duplicate this load.

ocabj
November 2, 2007, 10:58 PM
WARNING: The following information contains loading data that exceeds SAAMI specifications and may be harmful to your firearm and your safety. Take extreme caution in the event you attempt to use any of following data.

Awhile back I worked on developing an MK262 Mod 1 duplicate load using Hodgdon Varget, 77gr Sierra Match Kings, LC brass, and Winchester primers.

The load I came up with is 25.3gr of Hodgdon Varget with a COL of 2.260" (magazine length).

http://www.ocabj.net/gallery2/d/1008-2/mk262mod1_handloads_group.jpg

Note: The goal was to get a load that produced the same muzzle velocity as the known published MV of actual MK262 Mod 1. Accuracy wasn't the goal.

If accuracy was the goal, I would have used a significantly milder load. 77gr BTHPs (Sierra or Nosler) do better in the low 2700 range from what I've found. My Service Rifle short line load moves at around 2720 fps in a 20" 1:7 twist SR competition barrel.

The hot load of MK262 Mod 1 is a bit excessive, but I think it's necessary if the military wants to use it on all of their M16 platform firearms, from the standard issue 20" A2 to the 14.5" M4. As hot as MK262 Mod 1 is, it just barely crests above the 2650fps MV in the 14.5" M4, which ensures it'll stay supersonic until around 700 yards.

When reloading for the AR, especially with hot NATO pressure loads, I highly recommend you use either CCI 400/BR4/milspec or Remington 7-1/2. I discourage the use of Winchester primers because from what I have experienced, Winchester primers tend to pierce or blow out of the pockets in the AR15.

mightyike
November 2, 2007, 11:20 PM
When I was younger and used to reload more (haven't for 15 years but restarting-long story), I loaded as hot as possible...77 grains H-870 in my 264 mag with 140 grain Sierra HPBT's (max loadings in books around 73 today)....now that I am restarting, I'll back off. I just bought a 223 WSSM from CDNN and a Sendero 264....but I think I'll load more conservatively. I think hot and HV and high pressure is a young man's thing....it was sure mine.

crux
November 2, 2007, 11:23 PM
Start a Hornady 75 bthp(OTM) @ 2700fps, it should fragment at 200 yards (Frag velocity stated at ~2200fps, calculated bullet velocity 2262fps at that range(Hornady)). I know I can run that bullet to 2750fps without exceeding published data(chrono, 20" barrel).

Now, if you bust a gut, and push that bullet to 2850, you still won't make it to 300 while maintaining the 2200fps frag threshold. I personally am satisfied with a reasonable 200 yard load. If I have to poke holes in you at 300 yds or beyond, so be it, I will let you bleed out a long ways away. Its up close and personal that I really start to worry about ammo performance.

The Black hills 262markwhatever stuff is so hot, some sources recommend you do not reload the brass.

threefeathers
November 4, 2007, 12:43 PM
I have a bunch of M262 and it Chronoed at 2720 avg from my HBAR, that is closer to the published data. What was your altitude when you chronoed. I get 2700 by using 24.5 grains of Varget and almost 2800 from 25 grains.
I'm happy with the 24.5 grains

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