5.56 Reloading Question(s)

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Jlr2267

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Never hand-loaded 5.56/223 before so I have a question or two if someone could help me out. My rifle is 1:7 twist, but all reloading data I've been able to find (with the powder I have available) is from a 1:12 barrel. I plan to use the following (based on 1:12 twist, 20" test barrel):

CCI #41 Primer
Lake City Brass
Mil-spec FMJBT 55 gr bullets seated to 2.25" OAL
Reloder 7 @ 20 grains to start

The above combo gives ~2800 fps from the 20" test barrel.

Questions: (1) can I push a jacketed bullet this fast in a 1:7 barrel w/out it coming apart and (2) is there a significant difference in CCI #41 primers and standard small rifle primers, like Rem 7 1/2? I only have the CCI #41 but the loads I've found only list other small rifle primers :cuss:.

Thanks in advance for any advice.
 
That speed is fine for that twist.

Cci41 is harder with a magnum charge. Use Speer data, as they often use mag primers. Avoid max load if you substitute for a cci41. All ar15s should avoid standard CCI primers. Ccimag and cci41 both use thicker cups which prevent slamfires in floating firing pin applications. I've observed this first hand.
 
Yes, you can use load data for any twist barrel safely, though you may not get the best accuracy with some combinations. You can push most jacketed bullets a lot faster than that without problems, I don't think you'd see the bullet coming apart at any .223 velocity.

As long as the primer is small rifle, the brand doesn't matter.
 
Bullet that fast is ok. Primer is said to be like a magnum. The Reloder 7 for a 52gr speer hp bullet shows a maximum of 20.5. I would reduce this by 5% or 10% to start. The powder looks on the fast side for bullets heavier than 55grs. Unless you have better data you trust?
 
Thanks for the input. I thought I had read somewhere that with a "fast" twist barrel, some jacketed bullets would spin themselves apart after exiting the barrel
 
Speer says varmit bullets may come apart

I don't have it in front of me so I may be wrong. I believe Speer manual #14 says not to load varmit bullets over 3,000 fps or they may come apart. Something about how the bullet is constructed.

It seems like they said it would rotate and some incredible rate like 300,000 rpms.

I'm probably wrong.
 
Sierra 55 grain load data goes up to 3,100 fps out of 1:7 20" AR. M193 is about 3,200 fps out of a 20" AR.

Your load should be fine.
 
3100 fps * 12/7 (twist) * 60 (sec/min) = 318,857 RPM (trailing decimals rounded to 0)

Yes, they do spin rather quickly.

Just for fun: 3100 fps * 12/7 = 5314 rps.
5314 * 2pi = 33391 radians/second
surface velocity is then 33391 radians/sec * r (.223/2)
3723 in/sec = 310 ft/sec
now, since tangential acceleration is v**2/r, we've got the surface acceleration as
310**2/(.223/24) v**2/(radius in feet) = 10359604 ft/sec**2
which is 321726 times the force of gravity (32.2 feet/second squared)
The acceleration diminishes in linear fashion as we approach the axis of rotation where, of course, it is 0.

Now, if we knew the jacket thickness we could set up the integral and find the force normal to the surface trying
to tear the bullet apart and, knowing this, we could calculate the hoop stress in the jacket material. This is left
as an exercise for the reader. :)
 
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.224" Bullets tear apart in AR Rifle 1-7 twist.

Spade5 makes a good point, news to me. Speer FAQ >
Q. I'm shooting 50 grain soft points in a 223 semi-auto and the bullets are coming apart in flight. What's wrong with these bullets?

A. Nothing. Most likely, your rifle has a twist rate of 1-7 inches, intended for 62 grain military ammo. Several bullet makers compared notes and all had the same observation: muzzle velocities over 2800 ft/sec in a 7" twist will tear apart conventional 22 caliber bullets. Try our 62 grain FMJ or 70 grain semi-spitzer to keep bullets together.

Handloaders must be aware of twist rate when shopping for a 223 rifle. The standard 12" twist is best for varmint-class bullets.
Click to expand...
http://www.speer-bullets.com/getstarted/faq_bullets.aspx But like i said above
the jackets, if damaged by a rough throat/lead, may come apart sooner.
Click to expand...
I would test it if i owned a 1-7 twist.
 
I've used both types of primers interchangably in my 5.56 handloads.... I've never had an issue.
I try to stick with the magnum primers, just because they're thicker, but both have works quite fine for me.... thousandS of rounds ;-)

Mike B
 
The velocity of the load should be fine. I've driven 52gr HPBTs from 1-7 twist ARs faster than that "magic" 2800-fps without issue. Really thin skinned varmint bullets under 50gr may be a problem, never tried them. Anything heavier and relatively conventional in construction should be good to go.

However, I wonder if RL-7 will give you good results and operation. I'm assuming you're running an AR-type action. Try it and see, but I'd be more confident using something like H335, 4895 or anything in that general burn range.

FWIW, I drive Hornady 55gr FMJBTs to 2840-fps from a 16" Colt 6920 and haven't had a jacket come apart yet. But I have seen it done using 75gr match bullets by Highpower shooters: Ten shots, 9 holes and jacket fragments 2 targets away. I never did ask how hard he was driving those...

(I've also been on the range when 2 different shooters lost .308" match bullets on the way to 600-yard targets. Was pulling targets for the first shooter and spotting the second. Sometimes things happen.)
 
can I push a jacketed bullet this fast in a 1:7 barrel w/out it coming apart

Rule3's link (and mine above) leads to Sierrra AR15 data with a 20" 1-7 twist barrel. This makes no sense if Sierra tested all the bullets. Unless Sierra only chronographed the bullets, not checking groups on target?? http://accurateshooter.net/Downloads/sierra223ar.pdf The only way to know is, do your own testing.
 
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I have some real light Sierra bullets that I used when I had a 1:12 bolt rifle. I called Sierra to see about shooting them in the AR. One of the bullets was actually made for the 22-250 so it was made for extreme speed.

So it depends on have the bullets are made and designed. I see no issue in shooting your 55 gr bullets in your AR regardless of the twist.

Heavier bullets would probably do better.
 
I've had really good results with RL-7 and RL-10x. Both with cannelured Hornady & generic 55 FMJBT. No crimp. Mixed range brass. Plain CCI & Win. Primers.

All shot out of 1:7 barrel.
 
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moxie said:
I've had really good results with RL-7 and RL-10x. Both with cannelured Hornady & generic 55 FMJBT. No crimp. Mixed range brass. Plain CCI & Win. Primers.

All shot out of 1:7 barrel.
Click to expand...
I would think crimp is critical for a semi-auto...were you loading for a bolt rifle?

My bullets are mil spec (generic) 55gr FMJBT with cannelure. I had planned to use a moderate crimp.
 
Bullet Blowup

http://www.ar15.com/forums/t_6_42/437636__224_Bullets_tear_apart_in_AR_Rifle_1_7_twist_.html
th_BulletBreakUP3_zpse58731b9.jpg
[/URL][/IMG]
th_BulletBreakup1_zps330fa29d.jpg
[/URL][/IMG]
th_BulletBreakUp2_zpsbf6d6738.jpg
[/URL][/IMG] I had a problem 243win barrel back in the 70's that left lead smears on the targets and others that keyholed.
 
I'm new here, but a long time ago we were one of the first units issued the M-16 in Vietnam. I can't tell you how many men died due to its jamming. You'd get the first off, then it would jam. You pull real hard on the charging handle, and you tear off the back of the bullet, then you were screwed, and maybe dead.

It amazes me that such a POS, evolved into a fine rifle in only 4 decades. In a year although I carried an M60, I also had my M-16. When it worked the round was a nightmare for enemy surgeons. The bullet if it hit soft flesh, was an in and out...didn't even slow them down.

However, hit a bone, or a branch in flight and with the bone the bullet tumbled inside the body. Hitting a branch or leaf and you'd get a messy Yaw when it went in sideways...I hit a man in the shoulder once and it left a huge Grapefruit size mound on this thigh. It had blown his insides down to his upper thigh.

I am glad that the problems have been mostly resolved. Its also reassuring that so many have a battle rifle should things go "south" in this country.

You young men today, make up the largest army in history. Soon all that practice may come in handy when your called to Stand up for America.

Reading these posts makes me proud, and gives me hope that America's "silent army" is well armed, capable and ready to engage all threats, no matter where it comes from.

I have seen Communism, Socialism or Progressives or whatever their new name of the day is... an unarmed population are always the first to lose their Rights.

"Those who turn their weapons into Plow Shares... will plow for those who didn't"

I think my generation, feels we are leaving America in Good Hands.

Tom
 
jlr2267,

the sierra reloading manual has a "223 remington (ar-15)" section. that would be a good manual to have, in your case.

murf
 
I managed to get some 3031 and have a few loaded w/that and a few w/RX7...all are in the 20gr to 22gr range for testing.

What a PITA this cartridge is to load! I had mixed brass, all needed trimming, and one particular brand stuck my die 4 times ($#%@!) before I finally scrapped about 80 pcs of it. 90% of the brass had crimped pockets. Took me 4 hours just to prep 200 pcs.

Still can't figure out why my COAL is varying 0.01"... that's a new one on me after all these years...keeps it interesting, I suppose.
 
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