Why Are My .223 Loads So Much Slower Than The Chart?

[UtopiaTexasG19]

Until I get a chance to buy in some different recommended powders for the
.223 such as Varget and the IMR 8208 I have been trying out some H4895 I have on the shelf but my loads are comming out averaging 450-550 fps slower than the Hodgdon charts depending on the charge. I am using the exact new Winchester casings fully sized and checked for lenght, the exact 55gr. Sie SP bullets and exact Winchester SR primer. I also have the lenght at 2.200" as per the chart. I believe that my chronograph is working properly as it is consistant with fps and my electronic weigh scale for powder checks out perfectly so I am at a loss why these test rounds are so much slower than the Hodgdon chart. These rounds in fps are in the same general fps area as some cheap Wolf and Brown Bear I borrowed from a neighbor. The only difference I can see is that the Hodgdon chart states a 24" barrel was used and mine is a 16". Could the barrel lenght make that much of a difference? BTW-These rounds are super accurate in my .223 and I am shooting 3" groups at 50 yards with iron sights. For my poor shooting abilities this is phenominal!

[wncchester]

"The only difference I can see is that the Hodgdon chart states a 24" barrel was used and mine is a 16"."

That's part of it, the fact that your rifle isn't the same as Hodgedon's is the rest. Manual makers tell us what they got in their rig, they haven't a clue how it will work for the rest of us.

[griz]

These rounds in fps are in the same general fps area as some cheap Wolf and Brown Bear I borrowed from a neighbor.

Do you mean that other ammo in your gun clocks about the same speed?

Do you have a 22LR to check the chrono with? That's usually what I do since it is cheap and easy. If plain ol' bulk 22 registers about 1200 from a normal length rifle barrel, I assume the chrono is OK.

[UtopiaTexasG19]

Yes, I do have a Marlin rifle and some .22 Remington bulk long rifle bullets on hand so I'll try some out to check out the chronograph.

[TMD]

Your barrel being 8" shorter then Hodgdon's test barrel is where the difference it. When you shorten the barrel you generally loose about 50 fps per inch.

[tom234]

This might be an interesting read......
http://www.accuratereloading.com/223sb.html

[Doodlebugger45]

At first when you said they were 400 fps slower than the reference, my thought was that just sounds way too much slower. But when you mention the 16" barrel, that sounds about right to me. It's not an exact science, but going down to a 16" barrel will have a dramatic velocity effect for a cartridge like .223. Cutting the barrrel off is not really a linear effect. Going from 24" to 22" is not a big deal because you are just about out of expanding gas anyway for those last 2 inches. But going from 20" down to 16" has a very big effect.

[Jimro]

If you are reloading for accuracy the powders you listed are fine. If you want higher velocity, you'll need a faster powder. Compared to the H4895 you are using, something like H4198 might be able to give you a velocity boost in your 16" barrel as it should achieve a more complete burn and build more pressure before the bullet exits the muzzle.

However, I can't predict whether or not the gain in velocity will have any affect on accuracy or whether or not the gain will be appreciable in your rifle. This is a problem peetzakilla should be all over....

Jimro

[Brian Pfleuger]

I'll give it a go, Jim, thanks.

Generally, the powder that produces the highest velocity in a long barrel will also produce the highest speed in a shorter barrel... the trade-off for keeping that velocity is muzzle blast.

Usually, you can find a powder that gets you close to the same velocity (16" velocity) but reduces muzzle blast. You'll never get close to 24" velocity from that short of a barrel.

This is where QuickLoad really shines. Since I don't have a working PC at the moment, and have never loaded long OR short barreled 223, I can't give much information.

Where you want to draw the line between muzzle blast and velocity is up to you. However, if that load is accurate and near book max, you probably can't expect much more. All you could (probably) do is get the same thing with less blast.

[Unclenick]

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.


I think Jimro is correct. With a 55 grain bullet the powders you mention are too slow for best efficiency. They are great with 69 to 80 grain bullets, but with 55's you will get better efficiency and gain 50-100 fps by switching to Reloader 10X. The problem is you can't reasonably compress enough 4895 in the case to get there, even though the pressure would be safe.

In 2006, Handloading Magazine had a Charles Petty article in which Petty used 24 grains of Reloader 10X and various primers under a 55 grain V-max bullet. It appears to me you could get 100 fps more with that load, but since it isn't a load tested in a pressure barrel, you should work up to it from 23 grains, which is Alliant's published "recipe" with CCI 400 primers and IMI cases. Do the workup in 0.2 grain steps. (IMI cases tend to be heavy, so I wouldn't be surprised to see a Winchester case use a little more powder than the Alliant recipe does just to match its pressure anyway.) Petty used a range of primers and got 150 fps difference just based on the primer choice, as some cause higher pressure than others. Your WSR's should be fine.

Also, be aware that the .223 Remington's SAAMI Maximum Average Pressure (MAP) of 55,000 psi is an oddball because it is so close in magnitude to the the SAAMI copper crusher MAP of 52,000 CUP. Usually when you change from CUP to psi, you see a bigger jump than that. The .243 Win, .270 Win, and .308 Win all were rated for 52,000 CUP MAP, too, but their PSI MAPs are 60,000 psi, 65,000 psi, and 62,000 psi, respectively. I suspect something funny with the .223 measuring setup. The European CIP uses 430 MPa (62,366 psi) for both .223 Remington and 5.56×45 NATO as the MAP. Having fired European surplus .223 ammunition safely, I don't feel particularly at risk for using their MAP instead of SAAMI's. When you do, it lets the powder charges grow about 6% (though watch out for that to be high when the load is compressed). Velocity increases in rough proportion to the powder charge, so that's another 180 fps out of 3000 without exceeding the European numbers.

Anyway, back to your OP. Below is a chart of velocity vs bullet position in the barrel for the Hodgdon 4895 load. It predicts your shorter barrel will account for 280 fps of the velocity difference you got. The other 100 to 170 will be due to your chamber and bore dimensions, or your chronograph, or both.

[mehavey]

For a true 16" barrel, try these:

Cartridge .223 Rem. (SAAMI)
Bullet .224, 55, Sierra SP 1360
Cartridge O.A.L. 2.200 inch
Barrel Length 16.0 inch
Constant 52,00psi Pressure

Powder        Wt(gr)  %fill	V(fps)	P(psi)	%Burn
IMR 4198	21.0	97	2,914	52000	99
Reloder-10x	22.4	98	2,940	52000	99
Accurate 2015	23.4	100	2,918	52000	98
Hodgdon H322	23.6	101	2,951	52000	96

THESE LOADS EXCEED SOME MANUALS
CHECK YOUR RELOADING MANUAL FIRST !!
.

[UtopiaTexasG19]

Thanks for all the replys, also the very interesting figures!

[243winxb]

A gas system might give lower fps then a bolt action.

[mrawesome22]

If for no other reason, Quickload is good software for giving burn times in different barrel lengths.

But as stated, you need a faster powder for your short barrel to get complete burn.

[Jim243]

A gas system might give lower fps then a bolt action

Very good point. Also if you crimp or not, I am not saying you should but a mild (light) crimp would give the powder (H-4895) a thousanth of a second to build up to higher pressure and give more speed. The other factor is that Hogdgon used a 1:12 barrel in their tests and most of us use a 1:9 twist barrel which would take more energy to get that bullet through the barrel and show slower speed on the chrono, so between all these factors and the shorter barrel, I would not be supprised at what you found.

Varget and Benchmark would give you a faster reading, but be carefull since the max for these powders are a COMPRESSED load.

Jim

[Unclenick]

Actually, it turns out chamber dimensions and freebore length swamp out either gas system or rifling considerations. I've gone through the rifleing calculations before on another board.

I ran a .38 wadcutter at 800 fps. It had 210 ft-lbs of energy. With an 18" twist, the rotational energy was 0.57 ft-lbs. Changing to a 16 inch twist it went up to 0.72 ft-lbs. So, broadly speaking, the difference was 0.15 ft-lbs or about 0.07% of the muzzle energy. That corresponds to a change of about 0.3 fps per second in the muzzle velocity. I haven't run the numbers on a rifle bullet, but you can see the difference isn't going to equal shot-to-shot powder charge velocity errors. The post is #11, here, if you are curious.

For the gas system, it is a bigger effect, but still underwhelming. I calculated it once for the Garand. It seems to me the system siphoned off about 10 ft-lbs of energy from the barrel, which would be about 5 fps difference out of 2640 if it all was taken from the 173 grain match bullet. The real influence is less than that because the bullet is already near the muzzle when the gas port is exposed to barrel pressure, so that energy is subtracted mostly from the energy that was going to be thrown away in the muzzle blast. I'd guess 1 ft/s actual effect on the bullet velocity in that rifle is in the ballpark. For the M14 and M16, the gas ports aren't as far forward, so there is more time to influence the final velocity of the bullet, but the numbers will still be small. That's because the bullet gets most of its acceleration early in the bore at the higher peak pressure, as my previous graph showed, so the gas port is sampling pressure that is already well below the peak and can influence only the smaller portion of bullet's final acceleration.

Chamber dimensions, including volume and freebore length are the primary influences that alter load manual and commercial velocities in your gun, assuming you allow for any difference in barrel length. On the plus side, low velocity indicates the gun is running below the pressure the factory test barrel ran at, so less wear and tear. You could compensate for that, but the problem is being sure the difference is real. I've seen a chronograph err 200 fps in side-by-side comparison with a known accurate one (Oehler 35P). Unless you have some kind of calibration method for the chronograph for that kind of comparison, you can't safely increase the powder charge to match the expected velocity and know the pressure is OK. If you do have a known good chronograph setup that matches the SAAMI setup well, then, theoretically, as long as you didn't change powders you could do that workup.

[Jim243]

Now I am in trouble, Unclenick, I am the last person that would conter what you say, but I fail to see the comparison between a 5 inch 38 special to a 6 inch 38 special being comparable to a 16 inch and 20 inch 223 one in 1:12 to 1:9, also that change in pressure 72/57 is a 26.315789% change not 7% or so my math tells me.

And while I am not a fan of Garand's because of their weight (used them in ROTC), I can not see a rifle made to have a chamber that leaks gas because it's cut to Mil-specs to take any and all ammo being comparable to the AR who's chamber is quite a bit smaller and uses DI to move the bolt as opposed to the Garand that does not use a DI system.

Sorry but just my opinion
Jim

[UtopiaTexasG19]

BTW-After numerous folks, both through email and posts on other forums, recommended a try at Winchester 748 instead of the H4895 I went to town today and purchased a 1 pound jar of the W748. I'll load up 12 in the H4895 and 12 in the W748 tomorrow morning and compare the chronograph readings under the same circumstances and see what happens with this particular AR15!

[Brian Pfleuger]

748 is great in 22-250, I can tell you that much... 1/2 MOA at 4,435 fps with a 35gr Nosler BT.

[mrawesome22]

I've been messing around with Quickload and the 16" barrel.

Looks to me like H4198 would be optimal with that barrel length. I came up with slightly over 3000fps with 100.4% case fill with 96.08% powder burnt. 52k PSI.

I think you'll have good results with the 748 though. Quickload shows 2981fps at 52k PSI with 92.7% powder burnt.

H4895 looks awful lol. No wonder the poor results. At 100.7% fill, it calculates 39k PSI, 2657fps, and 87.33% powder burnt. HORRIBLE lol.

[m&p45acp10+1]

I have not crono'd any of them, but I have loaded a ton of rounds for friend's AR rifles. So far all did well with Reloader7, and H-335. All of them shot way more accurately then we were capable shooting.

[Unclenick]

Originally Posted by Jim243

Now I am in trouble, Unclenick, I am the last person that would conter what you say, but I fail to see the comparison between a 5 inch 38 special to a 6 inch 38 special being comparable to a 16 inch and 20 inch 223 one in 1:12 to 1:9, also that change in pressure 72/57 is a 26.315789% change not 7% or so my math tells me.

Jim,

If you reread my post you'll see I was saying the difference of 0.15 ft-lbs is around 0.07% (not 7%) of the bullet's muzzle energy (210 ft-lb), not of the change in rotational energy itself. The relevance of the .38 is merely to illustrate, in general terms, that the energy stolen from the powder to rotate a bullet is a pretty tiny portion of the energy that goes into accelerating the bullet forward, so it wont detract from muzzle velocity much. That will hold true for the .223, .308, .30-06, or any other rifled gun.

I could have picked one of the rifle calibers instead, but chose the .38 wadcutter example so the bullet would be a straight cylinder, as the energy computation for a rotating cylinder is simple algebra. A pointed bullet has a higher percentage of it's mass nearer the axis of rotation, so it will consume even less of the powder energy in gaining rotational velocity, relative to a cylinder the same weight. I can do a spitzer or a boattail of known ogive radius and radius origin for you if you need to see it, but it involves using calculus to integrate the mass shape with respect to its radius to find the rotational energy. I was merely trying to avoid complicating the demonstration with all the fancy symbols as most won't be interested in trying to follow it anyway. I assure you the principle will hold up: that rotational kinetic energy will be tiny compared to muzzle energy, and therefore will have only a very minor effect on muzzle velocity. Less than normal shot-to-shot velocity variation does.

As to the gas systems, whether you choose the Garand, M1A or M16, what your are interested in is how much kinetic energy the gas system steals from the powder on behalf of operating the bolt. Same as with rotational energy, the square root of that will give you the worst case effect on velocity at the muzzle (though in real life it will rob only some from the bullet and get the difference robbing the muzzle blast of energy). The Garand mechanism is dissimilar to the AR, but it's behavior (or the M14's) gives you a sense of the magnitude of energy levels involved operating a bolt automatically. Again, the point is just to illustrate it is a pretty small portion of the energy that goes into the bullet, rendering the influence on velocity pretty small.

[UtopiaTexasG19]

I went out this morning with fresh re-loads to compare the H4895 to the
W748 many had recommended since it appears to burn a bit faster and might provide a bit more acceleration out of the 16" barrel in my AR15. I used some previous loads to test the chronograph and was able to pull it in to 8 feet from the end of the muzzle before I received any error messages so I moved it back out to 9 feet for the readings. The 12 bullets in H4895 were loaded to 26.0 grains and the 12 bullets in W748 loaded to 26.3 grains which is the only load shown on my Hodgdon/Winchester chart for the W748 pushing the 55gr. bullets on hand. All were shot at 100 yards and my results do not match what others say the "quick load" program estimates for these powder loads and this lenght barrel.
The H4895 loads averaged a bit over 50fps faster than the W748 loads. The average on the H4895 loads were 2912fps and the W748 loads were 2854fps. My pattern on the targets was tighter with the H4895 but I get tired quickly, have a paulsy, and am just an average shot so that is not definitive. This has been very interesting so far but now wonder why I get slightly better results with the H4895? Oh well, more investigation.....

[PA-Joe]

Barrel harmonics has a lot to do with it. Each barrel vibrates at a differnt rate and if you're lucky you will be able to find that sweet spot.

[Brian Pfleuger]

Quickloads estimates are only accurate to your gun if they're customized to your chamber and load data. Still, the estimates of differences between the two powders should be more or less accurate with the default assumptions.

As to the accuracy difference, it's likely that best accuracy with any given powder may not be at max charge. I personally think you should find one that's CLOSE to max, or what's the point?, but that's my opinion.

On the chrony distance, don't worry about messing around with the distance. 15 feet is pretty much the standard. The fps lost between 9 and 15 feet is irrelevant and you'll never have to worry about muzzle blast affecting your readings.