Risk of using a hot load?

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canoetrpr

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Loading Nosler AB 140gr for a 280AI and found a good load at with 63 gr of IMR7828SSC. OAL is 0.025" off lands.

The load is a bit on the hot side; seems just 0.5 gr too hot as I start seeing very slight bolt face marking on the brass. Bolt is still easy to open.

Chronyed at 3170 fps. Another 0.5 gr takes me to 3230 fps and there is more prominent bolt face marking on the brass.
I'm going to be running this load in Wyoming in a couple of weeks antelope hunting. Temperature will be similar to now maybe less and elevation will be +1000 m.

The velocity the load generates is under the max velocity from Noslers book (about 3250) but from the slight bolt marking it is clear that the pressure is running bit high.

I'd like to use the rest of the time practicing rather than doing load dev. Would you guys risk running a load that is slightly on the hot side?
 
Whose brass are you using to build this load?

Some brass is considerably softer than others, and shows those marks more readily than others.

Regards, Dave.
 
Are you using Nosler brass? Nosler brass is soft, and I could not top 3140fps with 140gr bullets in either of my Coopers in 280AI, without the brass extruding, or the primer pockets growing.
 
When you start getting substantial increases in velocity (50fps) with .5 grain powder increase, you are verging on or well beyond max pressures. That velocity jump is telling you volumes so pay attention to it.

Ganderite knows his stuff but I am very surprised he isn't telling you to back off at least 2 grains.

When a half grain increases pressure enough to give that much velocity increase you are asking for trouble. It may not get you on the first reload but after that every shot fired through that case is a gamble. NO, I very much doubt the rifle will blow up or that you will even get lug set back but I can see incipient case head or neck separation right when you need it least.

Dropping back a couple of grains will likely hardly effect your velocities or zero. But I guess if I were in your position, strapped for time I would do something similar. Mind you, if I saw any sort of marks on the face of my case, I would have backed off immediately. But I also understand SH+T happens and we have to live with what has come about.

The parent cartridge is a conundrum in itself. The listed loads for it are well below the safe potential of the cartridge. Supposedly this is because it was introduced in weaker actions. The Ackley Improved version is just more of the same. By the way, I like Nosler or Norma brass.
 
I am not usually alarmed by marks on a cartridge bolt face, or by 50 fps increases in MV with a 0.5 gr increase in powder (I see MV's increase by 250 fps with three grs quite commonly), but..........

The Hodgdon Reloading Site puts the max load for a 140 gr bullet in a 280 AI with IMR7828SSC at 59.8 grs and just under 3000 fps.

Nosler's load data varies a lot from Hodgdon's.

Looking at Nosler's load data for the 264 Win Mag, and going by "gut feel" and experience, it doesn't seem right that the 280 AI with a 140 gr bullet at 3250 fps could outrun the 264 Win Mag by 200+ fps, and with such a fast powder. The 264 Win mag has a smaller bore size, but quite a bit more case capacity. To me, the two cartridges should have about the same MV with the same bullet weights, so the Hodgdon data seems more "right".
 
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280 AI load data from Hogdon 140gr bullet
Charge max charge
IMR IMR 7828 SSC .284" 3.330" 56.2 2,738 48,600 PSI 59.8 2,967 60,200 PSI

Nosler
max load 64.5 gr with 140 gr
Quite a difference, if your ammunition was to get warm left in direct sunlight on warm day you could have problems, primer blow,case jam in chamber or even worse.I would back off load some. deer or moose wont know difference between 100 fps
 
Sometimes Nosler brass gets a bad rap for being soft, but I don't believe that to be the case. Rather Nosler brass has a bit less capacity than it's competitors, thus a load that's fine with say Winchester brass causes loose primer pockets in the Nosler brass when both are cases are loaded alike. A pal of mine made up some .270 loads in Nosler brass soon after the stuff became available, and got 3200 fps with 130s from his 20" SAKO Mannlicher! I asked if he had worked up the load, and he said no, just used the load he had used previously in Winchester brass. It might be interesting to compare the capacity of Nosler brass with say fire formed Winchester brass by filling both to the case mouth, with a fine ball powder. I'll bet the Winchester brass holds more.
 
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Think I'm going to load some 61.5, 62 and redo some 62.5 and check what I get the best groups from and use it. Will probably go with 62 for practice for now for prone and sitting.

Doubt the groups will widen enough to make a difference to my accuracy in field positions during practice. This thing shoots at MOA or close pretty easily with most charges. However for the actual load I hunt with I am a tad obsessive and want to get the best accuracy at the fastest velocity I can safely :)
 
I guess I'm a tad surprised on this Nosler brass thing. I mean my projectile is Nosler AB, brass is Nosler powder is the same (though non SSC version) listed in their book and I can't seem to push velocities listed by them at the high end. Guess the chamber in my gun is tighter than the one they used.

Still a tad confused that even if that is the case and my pressure is running higher than their data at say 62.5 (about mid way between their min and max number) that I am not getting the same velocity they at their max. I no reloading expert but I would have though that the same pressure with the same powder, brass, projectile would generate velocity which is close? Also figured they would have left a margin of error at their max listed load before they saw pressure signs.

Still learning; lots to learn.
 
canoetrpr said:
I guess I'm a tad surprised on this Nosler brass thing. I mean my projectile is Nosler AB, brass is Nosler powder is the same (though non SSC version) listed in their book and I can't seem to push velocities listed by them at the high end. Guess the chamber in my gun is tighter than the one they used.

Still a tad confused that even if that is the case and my pressure is running higher than their data at say 62.5 (about mid way between their min and max number) that I am not getting the same velocity they at their max. I no reloading expert but I would have though that the same pressure with the same powder, brass, projectile would generate velocity which is close? Also figured they would have left a margin of error at their max listed load before they saw pressure signs.

Still learning; lots to learn.
Click to expand...

Trying to make sense out of minimum and maximum loads in manuals, given and achieved velocities and max pressures will drive you insane. Some cry openly, others internalize and turn to drugs and alcohol. Marriages break down, despondency sets in. Then it starts to get bad. Is that what you really want?

Your loads might be midrange in Noslers data, but they are over 3 grains and 200 fps over the data on Hodgdons website. When you get ejector marks, you've been done for awhile. You may get away with it forever, lots of guys do. On the other hand, compressed hot loads of 7828 can do some very unpleasant things when they sit for awhile. Manuals are all over the place on data and velocity, but you have to listen to your gun.

You've been warned. When the manuals say "use maximum loads with caution" it doesn't mean pull the trigger slower. It means you might not get there. You also may exceed it, and find another manual that agrees with you.
 
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