How far over book max to load when velocity is down?

[westernrover]

I recently loaded some 223 and fired them through a chronograph with my 5.56 NATO rifle. The published data was for 55 grain Speer SP and a 24" barrel. I used 55 grain Hornady SP and a 16.5" barrel. I'm skipping over a lot of details of my process to get to the point:

The cartridges loaded with 24.9 grains of Ramshot X-Terminator achieved a mean of less than 2640 fps vs. published data of 3278 fps.
The short barrel achieved 80% of the published velocity.

However,

The cartridges loaded with 25.3 grains of H-335 achieved a mean of 2820 fps vs. published data of 3203 fps.
The short barrel achieved 88% of the published velocity.

The cartridges loaded with 25.6 grains of Benchmark achieved 2956 fps vs. published data of 3264 fps.
The short barrel achieved 90% of the published velocity.

I was also able to achieve 90% of published velocity with StaBALL Match, albeit the data was for a different bullet.

I can understand that some powders are going to be more dependent on barrel length than others to achieve velocity. This should be true of slower burning and more progressive burn rate powders. However, X-Terminator is neither particularly slower or more progressive than the other powders I used.

Why is Ramshot X-Terminator delivering velocities 10% farther below published velocities than the other powders? On a comparative basis, the published data shows it should deliver velocities higher than H-335 or Benchmark, but I am getting velocities 200 or 300 fps slower. That's a LOT slower.

Should I keep loading it higher until I see pressure signs or velocities 90% lower than published? Or should I just write it off and load the remaining pound for plinkers?

 

[Walkalong]

Zero over. If you have to have that velocity, try another powder.

 

[GeoDudeFlorida]

I recently loaded some 223 and fired them through a chronograph with my 5.56 NATO rifle. The published data was for 55 grain Speer SP and a 24" barrel. I used 55 grain Hornady SP and a 16.5" barrel. I'm skipping over a lot of details of my process to get to the point:

The cartridges loaded with 24.9 grains of Ramshot X-Terminator achieved a mean of less than 2640 fps vs. published data of 3278 fps.
The short barrel achieved 80% of the published velocity.

However,

The cartridges loaded with 25.3 grains of H-335 achieved a mean of 2820 fps vs. published data of 3203 fps.
The short barrel achieved 88% of the published velocity.

The cartridges loaded with 25.6 grains of Benchmark achieved 2956 fps vs. published data of 3264 fps.
The short barrel achieved 90% of the published velocity.

I was also able to achieve 90% of published velocity with StaBALL Match, albeit the data was for a different bullet.

I can understand that some powders are going to be more dependent on barrel length than others to achieve velocity. This should be true of slower burning and more progressive burn rate powders. However, X-Terminator is neither particularly slower or more progressive than the other powders I used.

Why is Ramshot X-Terminator delivering velocities 10% farther below published velocities than the other powders? On a comparative basis, the published data shows it should deliver velocities higher than H-335 or Benchmark, but I am getting velocities 200 or 300 fps slower. That's a LOT slower.

Should I keep loading it higher until I see pressure signs or velocities 90% lower than published? Or should I just write it off and load the remaining pound for plinkers?

Hornady bullet, Speer loading tables?
You may or may not be over max already. You don’t know where the line is.
I suggest using Hornady data for Hornady bullets. Using mix-matched data is only good for finding a starting point and loading up to an acceptably accurate load.
You didn’t mention how any of these trials were on the target.

 

[jmorris]

I try to not get caught into the speed trap with SBR's, certainly wouldn't load over max data trying to get the same velocity they got out of a 26" test barrel with a 10.5" .223..

 

[Soonerpesek]

8” less barrel than the test loading……..
Should be 350-400 FPS less…….
You are right where they should be…….
………..IMO…………

 

[nettlle]

Zero over. If you compromise the recommended loading data for the velocity carrot you are very much on your own.

 

[westernrover]

8” less barrel than the test loading……..
Should be 350-400 FPS less…….
You are right where they should be…….
………..IMO…………

Well, why am I in one place with H335, Benchmark, and StaBALL Match, but a different place with X-Terminator? Why does the barrel length affect that powder by almost 700 fps, whereas it only affects the other powders by the 350-400 fps like you say?

 

[nettlle]

You may need a faster powder provided that you stay within the reloading specs. That goes along with short barrels. There are faster burning powders than the ones you are trying.

 

[westernrover]

Hornady bullet, Speer loading tables?
You may or may not be over max already. You don’t know where the line is.
I suggest using Hornady data for Hornady bullets. Using mix-matched data is only good for finding a starting point and loading up to an acceptably accurate load.
You didn’t mention how any of these trials were on the target.

It would be great if I had published load data for all the powders and all the bullets, but it doesn't work that way. The data I used and quoted is all from Hodgdon, not Speer or Hornady. I used Hornady bullets, but Hornady does not provide data for all the powders that Hodgdon does. They provide extraordinarily little data at all, and even that they charge for. It's reasonable that I use Hodgdon's data with Hodgdon's powders. Now Hodgdon provides data for a lot of powders, but not every bullet in existence. I decided that the Speer 55 gr. SP is reasonably similar to Hornady's 55 gr. SP and that I could use that data. If a person were to be a stickler about not using anything but data for a specific powder and a specific bullet, I'm ok with that, but I would feel pity for them.

I mentioned that I omitted a lot of details to get to the point. I didn't neglect to start at a lower charge mass and work up. That procedure is always worth following and even more so when changing a variable like the bullet maker.

Consider also that the published data is for 223 and my rifle is 5.56 NATO which should allow for several thousand more psi. I'm aware that I have no way of knowing how much more psi any additional charge mass would result in. I can model it in Quick Load, but I don't have anything like an RSI pressure trace. Nevertheless, I do have the means to look for pressure signs like hard extraction, extractor marks, primer cratering and flow. I didn't observe any of those things in any of my loads. I'm not surprised because there is a safety factor in the components and rifle chamber that published loads are unlikely to exceed.

 

[nettlle]

Give the chronograph a rest, load to the reloading manual specs, and then load for accuracy. Is velocity your main goal?

 

[westernrover]

You may need a faster powder provided that you stay within the reloading specs. That goes along with short barrels. There are faster burning powders than the ones you are trying.

3 of the powders I tried are adjacent on the burn rate chart. StaBALL Match is considerably slower burning. I could have tried a faster burning powder, but I think I was right not to expect higher velocities from one.

Let me be clear that I'm not trying to get 3200 fps out of my 16.5" barrel. The velocity of Benchmark at over 2900 fps with a 223 book load is more than I expected and all I need to be satisfied. I'm really quite happy to get velocities that are 90% of published data for a longer barrel.

But I didn't with X-Terminator. What's wrong with it? Too slow burning? Why did StaBALL do better then?

 

[westernrover]

Give the chronograph a rest, load to the reloading manual specs, and then load for accuracy. Is velocity your main goal?

Not at all. But 223 is dependent on velocity for terminal performance. As I've written, all the powders I tried are delivering satisfactory velocity except X-Terminator. ~2600 fps with a 55 grain bullet is lousy. For a max load, there's something wrong there. When other powders beat it by several hundred fps, there is something wrong.

 

[thump_rrr]

I recently loaded some 223 and fired them through a chronograph with my 5.56 NATO rifle. The published data was for 55 grain Speer SP and a 24" barrel. I used 55 grain Hornady SP and a 16.5" barrel. I'm skipping over a lot of details of my process to get to the point:

The cartridges loaded with 24.9 grains of Ramshot X-Terminator achieved a mean of less than 2640 fps vs. published data of 3278 fps.
The short barrel achieved 80% of the published velocity.

However,

The cartridges loaded with 25.3 grains of H-335 achieved a mean of 2820 fps vs. published data of 3203 fps.
The short barrel achieved 88% of the published velocity.

The cartridges loaded with 25.6 grains of Benchmark achieved 2956 fps vs. published data of 3264 fps.
The short barrel achieved 90% of the published velocity.

I was also able to achieve 90% of published velocity with StaBALL Match, albeit the data was for a different bullet.

I can understand that some powders are going to be more dependent on barrel length than others to achieve velocity. This should be true of slower burning and more progressive burn rate powders. However, X-Terminator is neither particularly slower or more progressive than the other powders I used.

Why is Ramshot X-Terminator delivering velocities 10% farther below published velocities than the other powders? On a comparative basis, the published data shows it should deliver velocities higher than H-335 or Benchmark, but I am getting velocities 200 or 300 fps slower. That's a LOT slower.

Should I keep loading it higher until I see pressure signs or velocities 90% lower than published? Or should I just write it off and load the remaining pound for plinkers?

Was NATO brass used?
Was it all the same headstamp?
Did it all have the same internal capacity?

 

[nettlle]

I have loaded for 16" barrels. When you get into barrels that short you are kind of getting off the reloading manuals charts. I wouldn't use the powders you are using.

 

[westernrover]

I think the advice to go 0 over is good. That's why I haven't continued to load X-Terminator higher until I got good velocity or saw pressure signs. But as long as I don't go there, I'm left wondering why it's not working.

Also, consider that our government goes far over and above published 223 load data. I'm not proposing following them, but it is worth contemplating why they do that. Personally, I don't like firing their over-pressure loads in my rifle. What's more, I can get better velocities with less pressure using a better powder than they do. So I have no reason to follow them. But why do they do it? To beat up equipment and get more contracts for their vendors to keep the MIC going? I sort of doubt that. What do you think?

 

[westernrover]

Was NATO brass used?
Was it all the same headstamp?
Did it all have the same internal capacity?

Yes.
All Lake City.
All fired one time since new in my rifle's chamber and bumped 1 thou.

 

[Jim Watson]

Not at all. But 223 is dependent on velocity for terminal performance. As I've written, all the powders I tried are delivering satisfactory velocity except X-Terminator. ~2600 fps with a 55 grain bullet is lousy. For a max load, there's something wrong there. When other powders beat it by several hundred fps, there is something wrong.

Simple. Don’t use Xterminator, quit trying to force it.

 

[Soonerpesek]

Well, why am I in one place with H335, Benchmark, and StaBALL Match, but a different place with X-Terminator? Why does the barrel length affect that powder by almost 700 fps, whereas it only affects the other powders by the 350-400 fps like you say?

Could be that X-Terminator needs more barrel length to get going…?
Is it a slower powder…?
ETA: does it need a magnum primer…?
I don’t have any experience with it…
I was only stating what my opinion was about the speed loss via the shorter barrel…
You can always disregard my statements if you wish, it won’t hurt my feelings…..

 

[westernrover]

I have loaded for 16" barrels. When you get into barrels that short you are kind of getting off the reloading manuals charts. I wouldn't use the powders you are using.

Why wouldn't you use those powders? Isn't H335 the closest thing to WC844 that's used in M4's all the time?
As for Benchmark and X-Terminator, they're as close to H335 on the burn rate chart as possible.
I was able to get great velocity out of Benchmark within published limits, comparable to Lake City ammo that's loaded with over 28 grains of WC844.
What powders would you use and why?

I contemplated using something from the T-32 family of powders. I could hope they would result in better accuracy, but I probably have some other factors interfering with that to be addressed before a powder could make a meaningful difference.

 

[westernrover]

Simple. Don’t use Xterminator, quit trying to force it.

That's exactly what I did. But it doesn't answer why. I proposed that I would just use up what I have left of the pound for plinker loads, but I also want to see what I can learn from my results.

 

[LV Gun]

Don’t ,,, I never load over maximum rifle or handgun. I had a friend do it even though I told him not to but he was a velocity freak when he pulled the trigger, all hell broke loose and I mean broke loose.

 

[GeoDudeFlorida]

It would be great if I had published load data for all the powders and all the bullets, but it doesn't work that way. The data I used and quoted is all from Hodgdon, not Speer or Hornady. I used Hornady bullets, but Hornady does not provide data for all the powders that Hodgdon does. They provide extraordinarily little data at all, and even that they charge for. It's reasonable that I use Hodgdon's data with Hodgdon's powders. Now Hodgdon provides data for a lot of powders, but not every bullet in existence. I decided that the Speer 55 gr. SP is reasonably similar to Hornady's 55 gr. SP and that I could use that data. If a person were to be a stickler about not using anything but data for a specific powder and a specific bullet, I'm ok with that, but I would feel pity for them.

I mentioned that I omitted a lot of details to get to the point. I didn't neglect to start at a lower charge mass and work up. That procedure is always worth following and even more so when changing a variable like the bullet maker.

Consider also that the published data is for 223 and my rifle is 5.56 NATO which should allow for several thousand more psi. I'm aware that I have no way of knowing how much more psi any additional charge mass would result in. I can model it in Quick Load, but I don't have anything like an RSI pressure trace. Nevertheless, I do have the means to look for pressure signs like hard extraction, extractor marks, primer cratering and flow. I didn't observe any of those things in any of my loads. I'm not surprised because there is a safety factor in the components and rifle chamber that published loads are unlikely to exceed.

This is a very long way of saying you don’t actually know how close you are to the line between acceptable pressure and excessive pressure. Which is exactly what I was pointing out: you don’t know.
The “why” is simple: the bullet, case, powder and barrel are not as efficient with one combination of components; it’s a good combination but not a great combination.
I would suggest a phone call to the ballistics team at Hodgdon. They might have a better answer.
Is all of the hostility in your post really necessary? You’re asking a question then lecturing the people trying to answer it.

 

[RetiredUSNChief]

Well, why am I in one place with H335, Benchmark, and StaBALL Match, but a different place with X-Terminator? Why does the barrel length affect that powder by almost 700 fps, whereas it only affects the other powders by the 350-400 fps like you say?

Because you're using different powders, each with their own burn characteristics and performance statistics under specific conditions.

This is, in fact, why there are different powders in the first place.

I'm not a reloader (yet), but I am an engineer (and I've occasionally stayed at the odd Holiday Inn Express). Powders are designed and tested under various conditions. If you change ANYTHING about those conditions, then the results are likely to be atypical of their test data.

Change even the manufacturer for the bullet and the results can be atypical. Most certainly, changing barrel length is likely to alter performance.

Varying the load beyond the limits specified MAY give you the specific results you're seeking, but at the very real expense of excessive stresses which the recommended powder loads were designed NOT to exceed.

We just had training at work today after an extensive investigation, developed specifically because a shipyard worker lost his life last December. Many important things came out of this, one of them being that deviating from established processes without authorization can set up conditions for tragedy, and that such deviations can result in systemic complacency when the people committing them don't see any initial harm resulting from their actions.


Don't violate those load limits. They are there for very important reasons.

 

[westernrover]

I didn't intend my posts to be hostile. If I'm not willing to accept an unreasoned answer, I hope that isn't received as hostility. While I agree that there are some things I don't know, I'm not completely ignorant of the pressure. Pressure does produce evidence. I am also aware of the possibility that I reached the book maximum while still being considerably under pressure. There is a distinct possibility that is the reason why the velocities are below expectations. If we define efficiency as the relationship of the potential energy of the powder to the resulting kinetic energy of the bullet, I want to know why the X-Terminator load is so much less efficient than expected. One possible answer is that the energy input is much lower than I expected. In that case, it's not much less efficient, but it's simply lacking in energy input. If the energy input is truly there, I can't think of a reasonable explanation for such low efficiency. This thread hasn't provided me with one yet.

 

[westernrover]

Velocity is a result of pressure over time. If we were to plot time or bullet travel on one axis and pressure on the other, we could integrate the area under the curve to derive the total impulse, that is, the force over time. It's this impulse for the length of the barrel that determines the muzzle velocity. If my charges of X-Terminator behind the bullet were producing a maximum average pressure that reached the SAAMI-specified limit, there are two explanations for why the total impulse would be as much lower than the other loads as observed.

First, the X-Terminator loads could be taking an extremely long time to build in pressure. This would reduce the area under the pressure/time curve between ignition and peak pressure. This is highly unlikely because the time from ignition to peak pressure is usually extraordinarily short. To account for the difference in impulse, X-Terminator would have to be so much slower burning that it would exhibit signs like hang-fire. StaBALL Match is considerably slower burning than X-Terminator, and it did not show such signs. A powder slow enough to cause this effect is unlikely to ever fit enough into the 223 case to ever achieve the SAAMI pressure limit.

Second, the X-Terminator loads could be dropping in pressure much more rapidly than the other loads. This would be characteristic of a much faster burning powder. Because most of the charge is converted to gas earlier, the pressure curve after the peak and further down the timeline contains much less area under it. However, there is no indication in the burn rate charts that X-Terminator has such a fast burn rate. This is exactly what I would expect from Accurate 2015. If X-Terminator has this much faster of a burn rate, then I could quickly get into trouble loading it over the published maximum. However, burn-rate charts and published velocities for X-Terminator do not indicate that it has this faster burn rate and expected lower velocities.