Thoughts on over max "Hot" loads

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So...looking to tap the wisdom from some of the seasoned veterens here.

I'm load tuning for a Kreiger barreled .223 and have seriously pushed beyond what the "book' says is max. The barrel was chambered for the 75gr Amax so I'm loading much longer than average. I started loading 10% below and came up in .2 increments, it started showing primer cratering at 26.1gr of varget (2gr over max) but no other signs of pressure. I had loads that ran to 27.3gr so I continued to work up, at 26.9 the load began to open up from 1" at 26.7gr to 2.25" at 26.9gr, these were shot at 200m. At 27.1 my first round pierced the primer and scared the CRAP out of me! I should add that at 26.5 I had less than 1/8 moa of vertical over 5 rounds

Now here's where I need the advice, I most certainly have a good node at 26.5-26.7gr and the velocity is an amazing 3170! Should I persue this load? Is it to close the point of failure? And could the pressure even without blowing primers hurt my rifle/bolt/bolt lug to action interface?
 
Well it's not uncommon for some sweet loads to go over max.
Seems 27 is you max. As long as you keep tight control over your powder drops you may stay safe.

There are some other over pressure signs that manifest over time, for instance, your primer pockets may become loose.
Keep an eye out for that one. If your brass gets loose, I may reconsider.
Also, knowing it's a right hot load, you best regularly screen your brass for head separation. In the long run, your chamber might not mind, but your brass could wear more quickly and be the weak link that becomes unsafe.

The reality of loading regarding pressure is that the published data really only reflects the test rifle they used which one assumes is set up to emulate a worst case scenario, and really, your rifle may differ greatly.

I've had load data before that proclaimed a certain load to be max, and in my rifle actually behaved like a minimum load and in the end, I too ended up 2g over max before I got it shooting right and there were absolutely no red flags to suggest the contrary.

Published loads are often conservative, you can even tell this just by studying the data carefully. For instance, I've seen advertised max loads topping off at 53000psi, when sammi max is 55000psi, and 223 design can go has high as 60000+psi.

Furthermore, the 75g Amax is a long bullet that gets seated at a much longer OAL. You'd be surprised the difference that makes in pressure. Unless your load data is for that exact bullet chances are you are running much lower pressure then the data states. However, your load with another 75g bullet seated at a standard OAL of roughly 2.25" may surely turn your rifle into a grenade.

So, in practice, I've found that published data is at least a grain lean of actual max, but don't quote me on that, and what is max on paper isn't actually max in real world. I'm not going to tell you to go ahead and continue what you're doing, but tread carefully, only your experience, and an intimate relationship with that particular rifle is going to tell you if it's ok.
One thing is for sure, if indeed it's a safe load for that rifle, awesome, but do not attempt to shoot it in any other rifle.

Knowing your velocity suggest you have a chrony, if you compare the FPS of a reload to the FPS of the data, that can give you some idea of how your rifle compares to the test rifle. For instance, if the Data says 2500fps, and you're getting 2200, then you know you're rifle is running a lot cooler then the load data.

Another thing to keep in mind, is that a rifle has multiple nodes, you don't have to run hot if you don't want you, you should be able to find another node in the mid range somewhere. That will let you run safe pressure and still be accurate.
You might need a faster powder to hit that spot just right tho'. Varget is awesome and all, but it's not the only powder on the market that is great for 223. I've shot some of my best groups with 3031 and 4198, lighter bullets of course. I've shot probably a thousand 80g and 75g Amax bullets using 8208.
 
75gr hornady bthp factory loads are running 2900 and change through the same rifle, but I'm loading at 2.51" coal vs the 2.25 that the factory rounds are loaded at. With the factory load I get zero primer flattening or cratering.
 
Conte said:
Another thing to keep in mind, is that a rifle has multiple nodes, you don't have to run hot if you don't want you, you should be able to find another node in the mid range somewhere. That will let you run safe pressure and still be accurate.
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This is what I kept thinking as I read the OP. What benefit is there in opting for the spicier of (probably) 2 nodal velocities ? Is it necessary in sub 30 cal shooting for some reason ?
 
Conte said:
Another thing to keep in mind, is that a rifle has multiple nodes, you don't have to run hot if you don't want you, you should be able to find another node in the mid range somewhere. That will let you run safe pressure and still be accurate.
Click to expand...

Bingo!

The problem with the normal warning signs of overpressure (flattened primers, cratered firing pin indentations, loose primer pockets, etc) is that they are not scientific measurements, merely wet-finger-in-the-air indicators. You can get overpressure for your rifle without any of them and venturing into max-plus loads and depending on them for safety is pretty dodgy to my way of thinking.

Some rifles will take considerably more propellent than the book maximum and do just fine. Others will be overpressure well short of the stated max. As well, high pressure strain accumulates, by some accounts. I'm neither a metalurgist nor a mechanical engineer, so I can't comment on that, but it's something to keep in mind.

Finally, yes, the book loads are conservative, but so am I and as Conte suggests, if there is a below-max sweet load producing the same level of accuracy, then that's the one I look at. I only get issued two eyeballs and one set of fingers.
 
This is a question that comes up from time to time, and the only prudent answer is for you to consider your rifle an individual rather than a clone, and consider published load data a guideline rather than a written in stone commandment. That data must be safe for everyone's rifle, not just yours, the trouble is that there are manufacturing tolerances between like rifles.

When I work up a load, I prefer to find the maximum load where pressure signs become evident; sticky case, ejector marks, etc, then I back off a full grain and consider that reduced load my working load. If its a load to be used in a hunting rifle, I seat to the cannelure, if there is one, and crimp. If there is no cannelure, I seat the bullet short enough that the round will cycle through the magazine without hanging up. If the load is for maximum accuracy in a target rifle, then I seat the bullet into the lands, and don't worry about the magazine length. This provides a margin of safety should I run into a cartridge case that has a bit less capacity or a bullet that is a bit heavier than normal, and anything I do from that point on, as it relates to adjusting the powder charge, or the bullet's seating depth, reduces pressure. The exception to the rule is when I'm searching for an accuracy load, as best accuracy in a target rifle is frequently with the load that produces the highest acceptable pressure. Having said that, a load should never leave marks on the case, but where it differs from the hunting rifle load is that it might only be only a couple of tenths of a grain below the load that produced pressure signs. Naturally this means that you must take steps to ensure the uniformity of both cartridge case capacities, powder charges, and bullet weights.

There are disadvantages to running at high pressure, even though you might see a slight accuracy gain. Brass has a shorter life before the primer becomes too loose in the pocket. A greater powder charge results in faster throat erosion. If you choose a corse, slow burning powder for case capacity, with a heavy bullet and deep seating, the load will be compressed; compressed loads take more time to assemble and in my experience can be less consistent.
 
ATOM said:
,,,,,,,As well, high pressure strain accumulates, by some accounts. I'm neither a metalurgist nor a mechanical engineer, so I can't comment on that, but it's something to keep in mind.,,,
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I'm neither a metallurgist nor a Mechanical Engineer either, but I'm on side with the pressure accumulation theory. Our HP (High Pressure) pressure vessels, including divers' bailouts, are regularly pressure tested. With time and use they loose their elasticity (work harden) and must be taken from service and destroyed.
 
If you need high velocity that much, perhaps it would make sense to consider a larger cartridge. Easier, safer, more readily available information for the velocity you require.
Grouch
 
i used to be one of the ones that pushed the limites. now i get a larger cartridge as it seems much safer. when you get larger cartridges your shoulder tells you when to stop.
 
The Barrel does show another node between 25-25.5gr, speed is 2960-3000. For those of you that know the .223, high 3100's is close to matching published data for the 22-250 and 75 gr bullets...pretty easy to get pulled in to flirting with that. I loaded 40 rounds at 26.6gr last night, now I'm thinking maybe I should pull them.
 
chappy said:
i used to be one of the ones that pushed the limites. now i get a larger cartridge as it seems much safer. when you get larger cartridges your shoulder tells you when to stop.
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Yeah, It took me quite a while to choose between the .223 and the 22-250, It came down to cost per round/barel life and I don't regret the decision, if I have to back off to the lower node then I will. If I had the 22-250 I would probably be asking if 3500fps was within reason.
 
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