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Old December 4, 2012, 11:22 PM   #1
kilotanker22
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max loads no pressure signs?

Hello all I worked up a load for my 270 wsm win model 70. I started low and worked up in half grain increments. The bullet is a 150 grain hornady SST and the powder is mag pro.

I have reached the maximum load listed in my manual of 68 grains of magpro and the bullet seated to the cannelure also using CCI 250 primers.

My question is whether or not this can be typical and if with no sign of pressure at 20 degrees should my pressure drastically change as temperature changes?
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Old December 4, 2012, 11:42 PM   #2
jepp2
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Quote:
My question is whether or not this can be typical and if with no sign of pressure at 20 degrees should my pressure drastically change as temperature changes?
If you checked 3 other manuals, I expect you would find 3 different maximum charges and some might be substantially different. So you may or may not be at the maximum for your rifle.

As temperatures increase, pressures will typically increase. Some will increase dramatically. But you didn't specify how much temperature change.
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Old December 4, 2012, 11:58 PM   #3
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The problem with visual signs of pressure is that by the time you start to see them you are already way into the danger zone. Certain powders will gain or lose pressure with temperature swings. In extreme cold I would stay well below the max load from any manual.
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Old December 5, 2012, 12:05 AM   #4
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Drail is right. Just because your not seeing any signs does not mean the first sign you see is you firearm failing.

Load for accuracy not to see how fast you can push the bullets. Typically you find the best shooting load somewhere between the minimum load and the max.

Different powders, primers, brass and bullets all play a roll in finding your guns best load. They also make the hobby of reloading interesting and enjoyable.

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Old December 5, 2012, 12:21 AM   #5
kilotanker22
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Well seams the only way to tell if I am licking on dangerous pressure is look for signs. But nothing no stiffness in the bolt or case signs. Plus shoots pretty good. Around one inch at 100.

Also I am talking 40 degree temperature change.
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Old December 5, 2012, 12:29 AM   #6
Brian Pfleuger
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Quote:
Originally Posted by Xfire68
Just because your not seeing any signs does not mean the first sign you see is you firearm failing.
Well, that's a little extreme.

Unless there's something seriously wrong with your gun there should be noticeable changes long before you blow it up. The particular signs that show up first will vary based on your components but there should certainly be signs.

You're not going to be in any danger with normal temperature changes either. Going from 0 to 90 degrees would dictate caution. Going from 40 to 60 to 70 isn't going to blow up your gun.
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Old December 5, 2012, 02:13 AM   #7
RC20
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What I am hearing now is that the best indicator is non linear chrono results.

If you were dropping into the zero degree range and below you might have issues with some powders, otherwise not.

And the max loads these days are still pretty conservative.

As stated, its not speed its accuracy that counts and speed does not make up for bad shooting.

What high velocity does is use up barrel faster. How much, hmm, probably not enough to matter in a hunting rifle, could be a factor in target shooting.

So, somewhere around a decent speed and accuracy and ok if its on the higher end.

Considering what they proofed the old 1903s at WITH the so called "brittle" receivers and still passed just fine, its damend hard to mess up a gun.

Which tells you what an amazing effort some people go to do it, you are fine.
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Old December 5, 2012, 08:22 AM   #8
mehavey
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Actually, the OP is not quite at the Max MAX by some references,
...but he's getting up there.

I'd fire the same case a half-dozen times and check for primer pocket fit thereafter.
That will tell him how close to the edge AT 20°F

He could be 7-9,000psi higher than that come summer
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Old December 5, 2012, 09:51 AM   #9
old roper
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What little I've loaded Win cases for the 270WSM their pretty tough and hard to read pressure signs.

Accurate site list 63gr to 70gr MagPro with 150gr bullet max velocity 3136fps and Nosler list 64gr to 68gr MagPro with their 150gr Bullets max velocity 3187fps. Nosler spec barrel used.

If possible you might want to check velocity.
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Old December 5, 2012, 10:12 AM   #10
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Kilotanker22,

You can look at my list of pressure signs. All brass is not equal, and you can often get pressure signs earlier in some brands than in others, which is why it's a good habit to knock a load down 5% and work back up when you change a component make or lot number. These days I usually use 6%, then increment in 2% steps when checking pressure. That way it's just 4 rounds to land back where I was.

Some powders have temperature compensation and some don't. Denton Bramwell found barrel temperature to be a bigger factor than powder temperature in his tests. So how you allow for temperature isn't simple to work out. It's both the powder and your rate of fire and how long rounds have to sit in a hot chamber that this will all depend on.

An old rule of thumb is to assume pressure will change about 1% for every ten degrees Fahrenheit, but that assumes each shot is from a cold barrel. Given the variables, therefore, you do best to develop loads and try them in your worst case warm barrel conditions for the kinds of rates of fire you actually use.
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Old December 5, 2012, 10:15 AM   #11
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It's quite likely that you could go higher but you got to watch out. Things can and do change very fast. But why the heck would you want to? Need more gun, get more gun. Pushing cartridges and guns beyond book is a little moronic. Not like choices don't abound or your .270wsm is a weak sister.
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Old December 5, 2012, 10:44 AM   #12
F. Guffey
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20 degree? (no sign of pressure at 20 degrees) AT 20°F, and then there is the Tea Cozy,

http://en.wikipedia.org/wiki/Tea_cosy

The secret to successful ice fishing is ‘keep your worms worm’ if a reloader wants to know what effect reloading in warm weather will have in cold weather, keep your ammo warm, carry your ammo to the range in an insulated/warm container, heat up some bricks, place them in the bottom of a cooler, use a thermostat, purchase the infa-red $27.00 dollar Harbor Freight/battery powdered temperature checker. When at the range fire the rifle a few time to get the operating temperature up to speed, then start the test.

I have heard it all my life “I am going to Colorado and I just do not know what effect the cold weather is going to have on my ammo”, develop loads for cold weather, develop loads for warm weather and develop loads for hot weather, then there are powders that are effected by temperature. The British made an attempt at replacing the 303 British round with a round that was said to be similar to a Ross round. The round was not suspect, the rifle needed improvement, but, the British was/did not change the powder, the powder cooked off before the trigger could be pulled and the barrel did not last long, pressure? was off the chart.

Though Winchester/Browning was a just a buggy ride down the pike from Springfield, Springfield thought they were the only makers of fire arms, and the English never heard of DuPont,

Even though one of the DuPont's went to Europe to learn the process for making smokeless powder.

http://ezinearticles.com/?Sales-Trai...les&id=1369924

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Old December 5, 2012, 11:10 AM   #13
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The secret to successful ice fishing is ‘keep your worms worm’....
I do have to admit. Mr. G, that your posts never fail to entertain.
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Old December 5, 2012, 11:10 AM   #14
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http://www.cowart.info/Florida%20His...0Biography.htm

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Old December 17, 2012, 11:19 PM   #15
reynolds357
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Accurate is listing 70gr or magpro as the max for the 150.
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