Sighting in an AR with .223 or 5.56, difference?

[DHolder]

Those shots were much better! As stated before, many things can effect POI. I recommend getting some more of the ammo you used in the last target, and work with that.

Make sure you are consistant with your basic rifleman skills and see if things improve.

You didnt say, how many rounds have you put thru that rifle? What kind of sights? All in all, that is a marked improvement, keep up the good work.

 

[Mr. Habib]

I can see how variations in the ammo can cause POI changes up or down, as bullet weight, BC, and velocity changes affect the amount of drop. I can also understand a group opening up as a result of changes in ammo, but I don't understand how changing ammo can move the POI right or left.

Different powders with a different burn rate even with the same bullet velocity can have different effects on barrel harmonics which can shift the POI. That's just one way. Different bullet with different BCs is another. One group shot from a cold, clean barrel. The other is from a hot barrel can change POI even with the same ammo. There are lots of possible variables that could cause this.

 

[RichardR]

Different powders with a different burn rate even with the same bullet velocity can have different effects on barrel harmonics which can shift the POI. That's just one way. Different bullet with different BCs is another. One group shot from a cold, clean barrel. The other is from a hot barrel can change POI even with the same ammo. There are lots of possible variables that could cause this.

Yup, Mr. Habib is "right on target" so to speak (LOL sorry couldn't resist).

Anyway this phenomena is one of the reasons some target shooters like to use heavy bull-barrels, they are not as prone to harmonic & heat distortion

 

[U.S. Patriot]

If I came off as a jerk, I apologize. I have learned to take all human error out of the equation before you look at the ammo, rifle, etc. as the problem. To the OP, I hope you get it figured out!

 

[sloughfoot]

I spent some time on the range today with my 1X7 Colt, chrome lined, HBAR, 5.56 chambered AR shooting some ammo over the chronograph.

Lake City M193, 5.56, 55 grain FMJ, 1989. 10 shots, Average 3245 FPS

Winchester M193, 5.56, 55 grain FMJ, 1994, 10 shots, Average 3241 FPS.

Malaysian M193, 5.56, 55 grain FMJ, 1982, 10 shots, Average 3109 FPS.

Remington/UMC, .223, 55 grain FMJ, 2000?, 10 shots, Average 3192 FPS.

Also, I tested the following;

M855 Nato, 62 Grain penetrator, TZZ 1995, 10 shots, Average 3189 FPS.

HSM Match, 75 grain BTHP, commercial match ammo, Average 2847 FPS.

This confirms that 55 grain commercial ammo and mil-spec 55 grain ammo is interchangeable. The pressures are virtually identical.

The 62 Grain M855 should only be fired in 5.56 chambers as all the sources also advise.

Read the data carefully, all of the cautions about shooting 5.56 out of a 223 chamber only refer to the M855 ammo.

And I agree with this caution too. But the 55 grain loads can be safely fired out of either chamber. Especially if that is all you got....

 

[mvician]

You measured MUZZLE VELOCITY.

CHAMBER PRESSURE is HIGHER shooting 5.56mm in a .223.
The muzzle velocty has nothing to do with it.

Now take that 5.56 round and shoot it from the tighter chamber of .223 and the pressure goes even higher.

Your line of thinking is dangerous.

 

[VERT]

Change in velocity/pressure can change groupings.

In my lever gun as I move from .38 spl to standard .357 to "heavy" .357, the bullets continue to shoot farther to the left.

I have shoot both .223 and 5.56 in my AR. In my gun the .223 shoot better groups. When I move to the 5.56 the groups begin to open up a bit. But both basically shoot the same POI. At least good enough for my purposes.

 

[sloughfoot]

Pressure/velocity are directly related to velocity/pressure.

Again, all of the cautions about not shooting 5.56 ammo in a .223 chamber are all referring to the M855 cartridge. Not the M193.

Do the research. The chamber leade is longer to accomodate the longer bullet of the M855 versus the the M193.

The M193 is interchangeable with the commercial 55 grain FMJ offerings. Both cases are filled up with powder. The M193 can't have more powder because it is already full.

I come out with this every couple of years when I get tired of reading the nonsense about the M193. I get beat down every time and soon I will stop this time too. And you guys can go back to repeating the same old untrue tune about the M193.

 

[U.S. Patriot]

I grabbed a value pack of 5.56 one day when I was shooting my Savage .223. I knew it right off the bat from the first mag. My rifle was literally jumping off of the bench. There is a definite difference in chamber pressure, and I will not take the chance.

 

[XtremeVel]

Lake City M193, 5.56, 55 grain FMJ, 1989. 10 shots, Average 3245 FPS

Winchester M193, 5.56, 55 grain FMJ, 1994, 10 shots, Average 3241 FPS.

Malaysian M193, 5.56, 55 grain FMJ, 1982, 10 shots, Average 3109 FPS.

Remington/UMC, .223, 55 grain FMJ, 2000?, 10 shots, Average 3192 FPS.

...

Wish I would of saw this thread earlier. I would of hollered to see if you'd be interested in running some Twin Cities from late 60's and LC from early 70's along side to compare.

I wonder if much of the confusion on the M193/.223 isn't due to some of the cheaper, underpowered stuff out there. As far as I have seen, all the more underpowered stuff out there does happen to be .223.

Not surprising it's a controversial issue...Heck, many ammo manufactures don't even appear to know their own offerings. I'm staring at some Precision Cartridge, Olympic, and Silver Bear in 55 gr offerings right now. They all are marked as being .223 Rem /5.56 x 45 NATO.

 

[sloughfoot]

I could meet you about 1600, are you free? I would like to check it out too. Minimum 10 rounds of each? PM me, I will check later.

 

[xring62]

Good velocity check here but velocity /pressure is not always related .Ive loaded 223 & numerous other cartriges for many years and have seen low velocities with high pressure that was TOO high.One thing that can change pressure is the bullets bearing surface ,this I always measure when changing a bullet with the same weight such as in a 55 grain,all brands can be differant on this . .Ive never had any trouble shooting .556 in a .223 chamber but maybe my chamber deminsions would except it. Anyway I reload my own ,being much cheaper and better than mil surplus,less dirty than Wolf.
On bullet impact yes every brand/bullet/bullet weight/case /primer/powder might shoot a differant impact point,Ive noticed very few differant brands /loads that hit at the same point,with my .22's ive seen groups 1-5 inches differance thats why I sight in for the best grouping 22 and dont mix and match.

I spent some time on the range today with my 1X7 Colt, chrome lined, HBAR, 5.56 chambered AR shooting some ammo over the chronograph.

Lake City M193, 5.56, 55 grain FMJ, 1989. 10 shots, Average 3245 FPS

Winchester M193, 5.56, 55 grain FMJ, 1994, 10 shots, Average 3241 FPS.

Malaysian M193, 5.56, 55 grain FMJ, 1982, 10 shots, Average 3109 FPS.

Remington/UMC, .223, 55 grain FMJ, 2000?, 10 shots, Average 3192 FPS.

Also, I tested the following;

M855 Nato, 62 Grain penetrator, TZZ 1995, 10 shots, Average 3189 FPS.

HSM Match, 75 grain BTHP, commercial match ammo, Average 2847 FPS.

This confirms that 55 grain commercial ammo and mil-spec 55 grain ammo is interchangeable. The pressures are virtually identical.

The 62 Grain M855 should only be fired in 5.56 chambers as all the sources also advise.

Read the data carefully, all of the cautions about shooting 5.56 out of a 223 chamber only refer to the M855 ammo.

And I agree with this caution too. But the 55 grain loads can be safely fired out of either chamber. Especially if that is all you got....

 

[PeaShooter]

to the OP. An Appleseed weekend will help you tighten those groups and teach you how to read your targets. It won't help with ammo differences, but at 100yds, you should be able to pick up any standard rack grade rifle and shoot 4MOA with mil surplus ball ammo.

Project Appleseed Home

 

[12many]

No


That's why you zero the rifle for an ammo type, whether it is .223 or 5.56 or different bullet weights.

If you're just plinking it doesn't matter if you mix ammo types. But if you are doing some serious shooting you want to stick to one type of ammo.

Upon reading this is it also safe to assume that reputable reloaded ammo and new ammo will shoot differently. All of the ammo I have put thru mine has been the same brand. of 5.56 so should I expect different results without the "me" factor thrown in?

 

[mvician]

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