So our duty ammo used to be a .223 Remington 55gr hollow point.

Our new duty ammo is a 5.56 NATO 64gr "protected point" round from Winchester. Essentially a jacketed soft point.

If the difference was between 55gr and 64gr NATO loading it wouldn't be a big deal but the .223 is a considerably lighter load that the 5.56. At 25 feet the 5.56 55gr NATO load will penetrate a Level III plate, .223 in 55gr will barely scratch it.

We zeroed the .223 at 50 yards, which gave a more or less flat trajectory out to 200 yards.

What can I expect from that zero with the hotter, heavier, load?

Is there a better flat-trajectory zero for the 64gr NATO load?

Depends on centerline distance between bore and reticle but I zero everything at 50 yds. It puts me within my ability to shoot at 200.

I shoot 62gr. Federal Fusion, 62 gr. M855, and 55gr .223.
There is no practical difference at 200. From a rest with a good shooter, I'm sure there would be a difference.

I agree also. Inside of 200 really won't be a statistically significant difference.

If you were shooting long range : 300M and beyond then you would want to pay close attention IMO.

Can play around here:

http://gundata.org/ballistic-calculator/

But your specific barrel lengths will likely matter also. If you are shooting 10" or 14.5" barrels.... your 5.56mm velocities might actually be lower than .223 velocities from a 20" barrel.

So you have to make sure the comparison is apples / apples IMO.

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Thanks for that link Sig209. Was wondering about .357 Max in a rifle with 180 gr over 158 gr. Didn't like performance on game of the 158 gr last two years and I think I'm upgrading to 180 gr XTP. looks like negligible real world trajectory differences. thanks again.

You will probably still experience best results with something very close to a 200 yard zero.

50/200, good approximation, but if you have access to longer range it is always best practice to confirm that zero at longer ranges.


Slight imperfections at 50 can lead to misses at 200, I see it frequently.

quote:

if you have access to longer range it is always best practice to confirm that zero at longer ranges.

Longest designated range that I have easy access to is 100 yds.

My home range is 25 yds and our department range is 45 yds.

I f it won't make a significant difference out to 200 then I'll leave things as they are.

We haven't been issued any practice ammo in the new loading yet. When I get some I'll test it out.

quote:

But your specific barrel lengths will likely matter also.

Some of our SWAT, command staff and secret squirrel types have 14" and even 10" but mine is a boring 16.1"

quote:

http://gundata.org/ballistic-calculator/

Cool. New bookmark.

Is this your new ammo at $33/bx of 20?

http://www.sgammo.com/product/...64gr-jsp-ammo-ra556b

I tried to find something similar in FMJ for a cheaper practice round but has no luck.

quote:

Originally posted by tanksoldier:
We zeroed the .223 at 50 yards, which gave a more or less flat trajectory out to 200 yards.

What can I expect from that zero with the hotter, heavier, load?

The 64 grain ammo may have more kinetic energy, but the 55 grain ammo likely has a higher muzzle velocity. I expect you're getting about 2900 fps MV with the 55 grain in your 16" carbine. SWAG of 2700-2800 fps with the 64 grain ammo.

I ran the ballistics through JBM with zero sight offset to see the true bullet drop.
At 100 yards the heavier ammo should impact within 1/4" to 1/2" of the 55 grain.

At 200 yards the 64 grain ammo likely drops 1-2" more than the 55 grain.

At 300 yards the 64 grain should drop 2-3" more than the 55.

In the overall scheme of things, probably not much drop difference when shot from ARs, for relatively close distance targets.

I gave up my rifle when I left patrol, but we use a 50 yard zero. In our jurisdiction it would be nearly impossible to justify a shot outside of the capabilities provided by such a zero and it allows us to put 50 shooters on the outdoor pistol range at once rather than having to cycle them a few at a time through the rifle range. We qual twice a year (mandatory, there are 2 more "voluntary" sessions to confirm zero). We use the old duty ammo to confirm zero and then use M193 (or even 55 gr .223) to drill and shoot the qual courses. The course is all 50 yards (25 for the flash light course)and in, so the difference in trajectories between the training ammo and duty load isn't all that significant. Expended duty ammo and any rounds that have been chambered in the field are replaced at the conclusion of training. All duty ammo is replaced bi-annually.

Yes. We replace chambered rounds. The recommendation is to rotate any round chambered and not fired to the bottom of the "third" magazine. The thinking is to avoid potential damage to the primer from repeated chambering of the same round over and over again. They have the same recommendation for our handgun ammo, but that is more out of concern for set back.

Something to keep in mind when switching among 223 and 5.56 loads is that not only can their elevation points of impact change, but windage (left/right) POI as well. Even for 100 yards it’s important to zero and confirm POI with one’s duty load, and not rely on training ammunition or other types.

Our duty ammunition is the Speer 64 grain Gold Dot that I imagine is similar to the Winchester. When my LE6940 is zeroed at 50 yards with it, the IMI 77 grain OT POI is about 2 inches left at 100 yards. The same is true of Federal 69 and 77 grain Gold Medal Match and AE223 (55 gr. FMJ). Hornady 55 grain TAP, however, shows no windage deviation at 100 yards.

quote:

Originally posted by tanksoldier:

Longest designated range that I have easy access to is 100 yds.

1.1 inches high at 100 will correspond very well with a 200 yard zero.



I would urge everyone who uses a rifle for serious work to confirm zero at the longest distance possible. I have experienced myself and seen many others try to use 25 or 50 yards and just bank on expected ballistics to work out and be on at longer range.

It often does not work out well from a training or competition standpoint, with small errors being greatly magnified as range increases.

For a duty rifle, I would want a rock solid zero.

quote:

Originally posted by sigfreund:
Something to keep in mind when switching among 223 and 5.56 loads is that not only can their elevation points of impact change, but windage (left/right) POI as well. Even for 100 yards it’s important to zero and confirm POI with one’s duty load, and not rely on training ammunition or other types.

Our duty ammunition is the Speer 64 grain Gold Dot that I imagine is similar to the Winchester. When my LE6940 is zeroed at 50 yards with it, the IMI 77 grain OT POI is about 2 inches left at 100 yards. The same is true of Federal 69 and 77 grain Gold Medal Match and AE223 (55 gr. FMJ). Hornady 55 grain TAP, however, shows no windage deviation at 100 yards.

Good point.

Barrel harmonics and other factors can indeed exhibit a shift of vertical and horizontal movement when changing between ammo, even with the same bullet weight.

quote:

I would urge everyone who uses a rifle for serious work to confirm zero at the longest distance possible

We're issued 60 rounds and told to load 28 in a 30 round mag... so I have 6 rounds to play with. I plan to get to the 100 yd range this week.

quote:

Originally posted by Sigmund:
Is this your new ammo at $33/bx of 20?

http://www.sgammo.com/product/...64gr-jsp-ammo-ra556b

That's the stuff.

One of the things you might want to consider is to check with JBM what the point-blank range would be with various zeros.

There is a little used setting in JBM called Vital Zone Radius. In there you set the radius (half the diameter) of the zone that you would call "flat trajectory." This is also known as point blank zone. Let's say that you want to have the bullet hit no more that 2 inches above or below your point of aim from the bore to the maximum point blank range. In other words, you want to know where you need to zero to have the longest possible distance without having to correct anything on your aim.

In JBM, enter 2 in the Vital Zone Radius (2 inches above and two inches below. Then enter all the standard stuff, like bullet, MV, height of sights above bore, etc.

When the results show up, go to the Output Data and look at Maximum PBR. That will be the longest range from the bore where you bullet will be inside of 2 inches above and below of your aim, provided you are zeroed at the Maximum PBR Zero displayed to the right of the Max PBR.

Just for grins and not wanting to mess up all my other data, I set the vital zone to 2 inches for my .308 Match load and then ran the numbers. My maximum PBR is 233 yards, with a zero at 199 yards. What this means is that if I zero at 200 yards (199yds), between 0 and 233yards, holding dead center, my bullet will be maximum 2 inches above or 2 inches below point of aim.

If I use 200yards as my zero, I run the numbers again, and I can see that for a 200yard, I'm 0.2 inches low at 25 yards and .9 inch high at 50yds. 2 Inches high at 100 yards.

So if all you have is a 25 yard range at which you can zero, you now can figure out where you need to be at that range to get your longest point blank range. With my rifle and my .308 load, I would zero a shade low at 25 yards

quote:

Originally posted by tanksoldier:

quote:

I would urge everyone who uses a rifle for serious work to confirm zero at the longest distance possible

We're issued 60 rounds and told to load 28 in a 30 round mag... so I have 6 rounds to play with. I plan to get to the 100 yd range this week.

quote:

Originally posted by Sigmund:
Is this your new ammo at $33/bx of 20?

http://www.sgammo.com/product/...64gr-jsp-ammo-ra556b

That's the stuff.

You are expected to perfect a zero with duty ammo with SIX rounds?

I hope there is never an officer involved shooting involving a hostage that goes bad
The penny pincher who mandated that is borderline negligent.


I wouldn't go to a for-fun carbine match with a zero that weak.

quote:

Originally posted by IndianaBoy:
I would urge everyone who uses a rifle for serious work to confirm zero at the longest distance possible.

Normally I would agree with you, and you are of course absolutely correct that short range zeroes and long range targets are a recipe for bad things to happen. The difference, though, is that patrol rifles are intended to be used at shorter ranges. If I must hit a small target at 25 yards, I’d prefer that my rifle had a positive zero at 50 yards rather than 200 yards. Your point is valid, and under-recognized even by people who should know better, but it works both ways: If I want precision at close distances, that’s where my gun should be zeroed, and I shouldn’t interpolate from a long range zero.

In absolute terms an error at 50 with a 200 yard zero will almost certainly be less than an error at 200 with a 50 yard zero. I nevertheless like my rifles to be zeroed with an eye to their probable targets. I would never attempt a hostage rescue head shot at 200 yards with even a good quality, but garden variety AR, and not even if equipped with a good magnifying optic.

quote:

Originally posted by IndianaBoy:
You are expected to perfect a zero with duty ammo with SIX rounds?

Didn't say that. I have to order some rounds, 6 is what I have to play with right now.

For confirming a zero six is more than enough. Either it's zeroed or it isn't.

We issue 64gr Gold Dot and do most training with M193. We have found the difference in zero at 50 yards to be smaller than the capabilities of most of our shooters.

I happen to agree 6 rounds should be good to get a decent zero. But in no way shape or form is it enough to confirm that the gun functions with different ammo.

quote:

Originally posted by sigfreund:

Normally I would agree with you, and you are of course absolutely correct that short range zeroes and long range targets are a recipe for bad things to happen. The difference, though, is that patrol rifles are intended to be used at shorter ranges. If I must hit a small target at 25 yards, I’d prefer that my rifle had a positive zero at 50 yards rather than 200 yards. Your point is valid, and under-recognized even by people who should know better, but it works both ways

I was considering this several days ago. With a 2.75" site offset and my chosen ammo (Hornady 75gr match) for a 100yd zero, I need -1.6" below POA @ a 25 yard zero. While I've grown accustomed to hold over @ close range, for a defensive rifle I'm thinking about changing my setup for a more CQB focus.