View Full Version : Why aren’t there more OTMs in 5.56
The vast majority of heavy OTMs seem to be .223. Why don’t more companies make 5.56 variants? My basic understanding of ballistics would make me think that if a shooter was trying to push distance and possibly fight wind, a higher pressure loading would increase muzzle velocity and achieve those effects better. Magtechs 262 clone is one of the few that seems like it’s moving quickly. Why not more?
ETA - meant IMI’s 262 clone, not Magtech.
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One More Time
07-10-22, 09:14
I don't think the magtech 77gr is available anymore.
I have a couple hundred of S&B 5.56 77gr OTM to try out.
Looks like their own projectile and not a SMK like the IMI.
A bit faster than the IMI on paper anyway.
https://i.imgur.com/UUYN4NYl.png
If a factory doesn't make their own precision bullets they have to buy from an outside source (i.e., Hornady, Sierra, Berger, Barnes, Lapua, etc.), cutting into profit margin and depending on an outside source.
The market sells cargo ship loads of cheap blaster ball (including steel case). People who want match-grade typically load their own.
Eurodriver
07-10-22, 14:07
I have tons of 5.56mm pressured OTM.
I made it. :)
turnburglar
07-10-22, 14:43
I mean.... What are we using to differentiate 223 vs 556? Pressure? Velocity?
I think it really boils down to: good 556 is harder to make than it looks like. Go on youtube and watch the "Cloning mk262" reloading series where a guy tries dozens of very popular powders and you realize how hard it really is to get close to factory 262 much less beat it. Lastly when making truly hot loads its hard for a large manufacturer to know what guns/chambers these are going into. As reloaders we get to work up loads for the exact barrel they going in. A manufacture just doesn't have that. Recently while shooting my buddy had Berger factory 73 gr that normally perform very well for him start popping primers bad once it got over 100*. It's not as easy as it seems. To avoid all these issues a commercial reloader will just find a lower and safer node.
IIRC I got 77gr reloads from freedom munitions and they made like 2450 FPS from my 14.5. I had a load that makes 2700 FPS FROM A 14.5 in my load development book but I know NO commercial maker would send that out to anyone.
Step one for true 5.56mm is crimped GI primers (typically a CCI 450 or a #34 military).
Western powders publishes their 5.56mm load data:
https://www.ar15.com/media/mediaFiles/18978/TAC_5_56_jpg-2448259.JPG
I prefer Varget for 77s, and that data comes from trading between competitive highpower rifle shooters.
...crimped GI primers (typically a CCI 450 or a #34 military).
Minor point, but isn't #41 the small rifle primer?
Minor point, but isn't #41 the small rifle primer?Dang. Thought I'd fixed that before posting. :eek:
turnburglar
07-10-22, 22:00
@Sinister: I agree that a primer crimp would help a lot. I regularly use 450 or #41 primers so that component isn't the issue, but I dont know how to crimp my own primers.
Would you mind sharing your load with Varget? I just got a jug and worked up to 24.5 gr under a 77SMK and had low/no pressure signs. Haven't checked for a Node yet, and wondering what is popular. If you dont want to post the load publicly a PM will do.
I just checked 3 different factory loads I have at home, never noting that one was 556 vs 223. All were 223 loads. Norma, Outback, Lapua all 223. I guess only Black Hills can sack up and make great 556 ammo. I guess that's why BH dominates contracts, as they should.
Federal still makes XM556SBCT3 62 grain bonded and T556TNB1 62 grain OTM which was made and sold for a hot minute. I have a few boxes left for BS testing back in the day.
PB
@Sinister: I agree that a primer crimp would help a lot. I regularly use 450 or #41 primers so that component isn't the issue, but I dont know how to crimp my own primers.
Would you mind sharing your load with Varget? I just got a jug and worked up to 24.5 gr under a 77SMK and had low/no pressure signs. Haven't checked for a Node yet, and wondering what is popular. If you dont want to post the load publicly a PM will do.I shoot 24 -- I use an H3 buffer for mid-lengths and an XH for 20-inch rifles (with collapsing stocks).
I used to use 24.5 but it crunches powder when you seat a 77.
The vast majority of heavy OTMs seem to be .223. Why don’t more companies make 5.56 variants? My basic understanding of ballistics would make me think that if a shooter was trying to push distance and possibly fight wind, a higher pressure loading would increase muzzle velocity and achieve those effects better. Magtechs 262 clone is one of the few that seems like it’s moving quickly. Why not more? ETA - meant IMI’s 262 clone, not Magtech. Sent from my iPhone using Tapatalk
In no particular order,
Shooters use 5.56 ammo in .223 bolt guns or suspect chambers locking them up, dropping primers, calling to complain. I think this is less than cited but still a factor.
Shooter knowledge or ability isn't enough to produce the gain. Normal .223 pressures and velocities are fine for those.
Shooters stretching loads out and seeing the gains are probably reloading.
Faster isn't always better. Bullets may prefer a certain velocity window. (Even when present, may be small enough to escape knowledge/ability.)
When we talk about a "5.56" variant, are we talking about just speed, or other stuff too?
Faster isn't always better. Bullets may prefer a certain velocity window.
This. We load our OTMs slower than we could because the accuracy is a little better for us.
I generally stay away from 5.56 MAX loads, but I do exceed .223 Rem pressure loads. I'm looking for a balance of velocity, accuracy, and long brass life.
I load my 77 grain OTM's with 24.2 grains of TAC (LC brass, CCI 450 primers, 2.250" COAL). Book 5.56 MAX is 24.8 of TAC. Book .223 Rem MAX is 23.4 of TAC.
In other news, I recently got 500 new Starline 5.56 cases, so I will be working up some new loads with those. Surprisingly I found the new Starline cases only 1 grain on average heavier than my average LC brass cases.
I haven't done any water capacity tests with these new cases until I have some fired Starline brass. Too hot out right now for this old man. I think I'll wait until fall.
I generally stay away from 5.56 MAX loads, but I do exceed .223 Rem pressure loads. I'm looking for a balance of velocity, accuracy, and long brass life.
That's what I do too. Lately though, I've been running current production CC 41s. And it seems like no matter how much I reduce the load, the brass is still roasted.... swipes, popped primers, etc. I literally pick up my brass and toss it all into the recycle bucket. ZERO chance of getting more use out of it.
That's what I do too. Lately though, I've been running current production CC 41s. And it seems like no matter how much I reduce the load, the brass is still roasted.... swipes, popped primers, etc. I literally pick up my brass and toss it all into the recycle bucket. ZERO chance of getting more use out of it.
Is that with H322 exclusively or with any powders your currently using? What are your velocities looking like with this new lot of CCI 41's??
Is that with H322 exclusively or with any powders your currently using? What are your velocities looking like with this new lot of CCI 41's??
I haven't really insulted H322 with those annoying ass primers. I've shot TAC and IMR 3031. Backed the 3031 off a half grain (from my Wolf SRM load) and still get swipes and a popped primer with 69 gr bullets only going 2850 out of a 20" bolt gun. 2850 is a decent velocity, but shouldn't be popping primers.
The factory Norma 69s were over 2900 fps for reference.
Mark, you think CCI 41’s have gotten significantly hotter in the past few years? That might explain my increasing velocity woes and wrecked primer pockets.
Mark, you think CCI 41’s have gotten significantly hotter in the past few years? That might explain my increasing velocity and woes and wrecked primer pockets.
I never tried them before so I have no history/frame of reference. There's a guy here, tommeboy, who claimed there's reports of 41s are popping on other forums.
For what it's worth, chasing an extra 50-75 fps isn't worth the potential problems. Do the wind on the difference and you will see 95% of folks most likely can't work the wind difference let alone the accuracy of the "system"
It just worked out this way for accuracy, my bolt gun is 23.6 8208 with the 77 TMK and the LMT 20" is 23.2. The semi is at mag length and bolt is longer, no pressure and at 3 loads, annealed each time. Both FGMM 205's
I always laugh at folks to dumb to find 5.56 online and will come in the shop asking for it and if we don't have it say "I only shoot 5.56 in my gun" -well guess your not shooting then are you? Keep in mind these folks are shooting at 25 yards.
For what it's worth, chasing an extra 50-75 fps isn't worth the potential problems. while I generally agree, the spread between different brands of factory 75/77 gr ammo is a little over 200fps. I assume each brand uses different powder, so arrives at a different “node” for production.
while I generally agree, the spread between different brands of factory 75/77 gr ammo is a little over 200fps. I assume each brand uses different powder, so arrives at a different “node” for production.
Referencing factory AND reloaders who chase velocity only "trying to beat the wind" I get it, fast efficient bullet is the way but the difference in a safe and accurate load and one blowing primers and not as accurate is what I referenced.
while I generally agree, the spread between different brands of factory 75/77 gr ammo is a little over 200fps. I assume each brand uses different powder, so arrives at a different “node” for production.
Point of reference, same 16" barrel, both 77 SMKs
Federal TRU T223M3, 2380
Mk262 Mod 1, 2630
BHA 62 TSX, 16"
5.56, 2900
.223, 2770
Looked for a 55 weight class difference, but I remember that the 55 GDSP 5.56 (d/c) and .223 were about that far apart too.
The difference in the TRU and 262 matters, start stretching them out (800-1000+) and the difference really shows.
I will say this and it was a one time experience, MK262 in a .223 LTR proves the over pressure hole in the receiver works rather well. Worst sound I ever heard and took a few minutes to make sure I wasn't leaking anything. I didn't know any better and then learned the difference in chambers and pressures.
Maybe it was a fluke, but I won't test the theory again.
National Match shooters will normally shoot a 68-77 grain bullet at 200 and 300 yards, and an 80 at 600.
There were a few years where the Marine chain of command told their teams no 80-grainers for the long lines (600 yards for the National Match Course and for the Palma Course fired with a service rifle at 800-900-1000 yards) because single-loaded ammo is not a standard military item.
The Marines gave away a LOT of points and lost. Often. Good for the Army.
While Army was shooting 80s and 7.62, Marine 77s would get to 1,000 having passed through trans-sonic and into sub-sonic speed. At Quantico we watched as one went "Blat" through the target, hit the impact berm, bounced back up-range and landed on the catwalk, spinning like a little top.
A young Marine bent down to pick it up for a souvenir, then dropped it, howling. That thing was only a second out of a rifle at around 55K psi pressure and heat.
So all of this reloading discussion is going way over my head. I’m in the Rockies of moving from CO to NC right now and transporting my guns and factory ammo alone fills up most of my Grand Cherokee. I can’t imagine adding reloading components on top of that.
As for the question on what we’re using to determine 5.56/.223, I was only referring to what they’re marked on the box from the factory. But the driving point behind the question was due to bullet drop and ability to fight wind. Shooting at 600m with the winds that can whip through the CO plains is not easy for someone that’s pretty much brand new to it.
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A young Marine bent down to pick it up for a souvenir, then dropped it, howling. That thing was only a second out of a rifle at around 55K psi pressure and heat.
I've often wondered about some of our lower velocity bullets past 1000 yards.... if the extended flight time cooled the bullet much.
turnburglar
07-12-22, 12:33
No it won't cool the bullet enough to touch it. It was only flying for a second, metal doesn't cool that fast. I have grabbed tons of pistol slugs right after shooting steel and without a glove its funny pretty quickly.
That federal velocity of 2380 FPS from a 16" barrel is why I got into reloading in the first place. I dont want to pay big dollars for neutered rounds. It might shoot good 100 yard groups, but shit will you notice your holding higher than any other load if you actually shoot 500 yards or more.
I recently changed my reloading mindset. I used to make loads well above any published book max, but once I got a few blown primers in my lower and realized I was only hurting my precious creed moor brass I looked for Nodes at or slightly below max.
No it won't cool the bullet enough to touch it. It was only flying for a second, metal doesn't cool that fast.
I was wondering about flights well over 1 second. But maybe there's some principles of physics beyond my knowledge that are at play.
I recently changed my reloading mindset. I used to make loads well above any published book max, but once I got a few blown primers in my lower and realized I was only hurting my precious creed moor brass I looked for Nodes at or slightly below max.
I've gone to small rifle primer Creedmoor brass for that reason. Hornady standard/large primer pockets actually hold up pretty good though. I run hornady pretty hot and have had 3-4 loads in some of it.
The reports I was seeing with the 41 primers popping was with some of the new wiz bang cartridges using small rifle primers. Part of what was found out was the brass was soft and less internal capacity than previous batches. At least with one guy anyway. Several other I seen were using 223 and popping primers. One was blanking, the other was blowing pockets. The one with the pockets posted and never came back to update.
My take on this is everything made in the last 2 years is suspect. QC no matter who it is get compromised when mad $ is to be made in big corporations.
As an example. I just got a bag of starline 556 brass to try. Local place had them. Got them home and they all measure 1.742"-1.746". I have not weighed them as I have them loaded up already for testing. This is the first time I have ever bought 223/556 brass. I normally use range brass for everything.
Another example, I have had 2 BA barrels and 2 Wilson Arms barrels I have sent back as they have bad chambers, bores with voids in the rifling. These were in the last year.
The reports I was seeing with the 41 primers popping was with some of the new wiz bang cartridges using small rifle primers. Part of what was found out was the brass was soft and less internal capacity than previous batches. At least with one guy anyway. Several other I seen were using 223 and popping primers. One was blanking, the other was blowing pockets. The one with the pockets posted and never came back to update.
My take on this is everything made in the last 2 years is suspect. QC no matter who it is get compromised when mad $ is to be made in big corporations.
As an example. I just got a bag of starline 556 brass to try. Local place had them. Got them home and they all measure 1.742"-1.746". I have not weighed them as I have them loaded up already for testing. This is the first time I have ever bought 223/556 brass. I normally use range brass for everything.
Another example, I have had 2 BA barrels and 2 Wilson Arms barrels I have sent back as they have bad chambers, bores with voids in the rifling. These were in the last year.
I just got 500 new 5.56mm Starline cases direct from them. Their item #3440 - 5.56x45mm Brass clearly states 1.745" - 1.75" O.A.L Mine measure right in that range as I sampled a random 30 or so. So I don't think that the OAL is a problem. As to weight, they weighed on an average about 1 grain more than the average for Lake City Brass I have on hand. I have not measured capacity, as I have not fired any yet, as I usually measure capacity with once fired brass.
https://www.starlinebrass.com/556x45mm-brass
I usually don't care about the length for my gas guns if they are a little short. But I was going to use these mainly for my bolt gun that I have been neglecting. I like to run my brass a little long but under max length. I feel it supports the bullet in the case and chamber longer. Having short necks can cause accuracy problems.
And the chamber in my bolt gun is really tight so brass has never grown very much even FL sizing every time. I set the head space on it very tight also. It is a savage so that is easy to do.
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