280 ai pressure

kman300

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Can someone explain this to me? The nosler 280 ai data and ammo is for 65k psi. 280 rem is 60k psi. After you fire form 280 rem in the ai chamber can you load that brass to 65k or is is only designed for 60k. And if this is the case, is the correct thing to do, other than paying for overpriced nosler brass, to neck up 270 to 30 and then down to 280 for a good fireformed case?
 
They say the .280 Rem is held to a lower pressure because of the semi auto rifles it was designed for.
That always struck me as odd as the same rifles were available in .270W.
 
Can someone explain this to me? The nosler 280 ai data and ammo is for 65k psi. 280 rem is 60k psi. After you fire form 280 rem in the ai chamber can you load that brass to 65k or is is only designed for 60k. And if this is the case, is the correct thing to do, other than paying for overpriced nosler brass, to neck up 270 to 30 and then down to 280 for a good fireformed case?

I had a Remington 760 pump in .270 Win with a rated chamber pressure of 65,000 psi and yet the rifle in 30-06 was only rated at 60,000 psi. And the lower pressure on the 30-06 was due to all the older firearms still being used.

Don't worry about the brass different head stamps, these cases are made to take the higher pressures. Just use the link below and measure the case just above the extractor groove to find that brands pressure limits.

"BUT" different manufactures use different grades of brass for the cases meaning brass hardness.

Simple Trick for Monitoring Pressure of Your Rifle Reloads
http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads

Below is a photo from accurateshooter.com, the reloader was a long range competitive shooter and he loaded the case until the brass flowed into the ejector and then backed off 1 or 2 grains of powder. This is basically the same test as the Hodgdon's link above showing base expansion.

NOTE, I use Lake City Brass in my AR15 rifle because it is the hardest brass you can get. But if i use softer brand .223 cases with the same load it will leave the same mark on the base as the case below.

index_zpsaiocbozg.jpeg


Below is a exaggerated image of the what measuring just above the extractor tells you.

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Bottom line, make a workup load after you fire form your cases and check for signs of pressure.
 
Generally speaking, the rifle is rated by the cartridge it's chambered for. Stanadards for each cartridge are set so that firearms and ammunition manufacturers have a "standard". It would be stupid if ammo makers loaded a cartridge to 70K psi but a rifle manufacturer chambered it in an action that was only good for 65K psi.

SAAMI and CIP pressure standards are just that - standards. It doesn't mean the brass can or cannot be used at a higher pressure - it means that's the maximum pressure set by industry as the standard for that cartridge. For some low pressure cartridges like 9.3x57, 30-30, etc - it is very possible to hot-rod your hand loads substantially and still be very safe IF you are using a strong rifle and good brass.

Pressure standards are generally set for the weakest action rifle they were commonly chambered for. US Springfield trapdoor rifles were the first 45-70 rifle, and the 45-70 pressure standard is set appropriately low. Yet the 45-70 cartridge is commonly loaded at double that pressure in rifles with stronger actions.

IIRC the 9.3x57 has a standard max rating of under 40K. If chambered in a M98 Mauser rifle and good modern brass is used it would be quite safe to load that cartridge up to 30-06 levels, even though that's probably 40%-50% over the CIP "standard" pressure rating for that cartridge.

That's why there is a difference between the pressure standard for 280AI and 280.
 
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So 270 brass is not stronger than 280 brass and there is no reason to buy a bag of 270 over 280 for loading 280 ai. Correct?
 
I have loaded my Remington 700 30-06 "warmer" than 60,000 psi, and as you can see below it has a big red warning about loading to 65,000 psi

That being said with a workup load and measuring base expansion you will be able to see what your brass can take pressure wise. Normally I never load "hot" because I want my brass to last and load lower than book. And where I hunted in the woods 40 yards was the average range a deer was shot at so you didn't need magnum velocities. Just remember each rifle and load with generate different chambers. As a example my Savage .223 with a 1 in 9 twist has a longer throat than my AR15 rifles and can be loader "warmer" than loads listed for .223 rifles with 1 in 12 or 1 in 14 twist barrels with a much shorter throat.

NOTE, now ask yourself "why" the 30-06 below was tested at a higher than rated pressure. (because someone asked the same question the OP did about the 30-06) ;)

EPcuYSG.jpg


Below my buddy CatShooter to put a end to a heated "discussion" posted the information below. So you can see how brass hardness varies and how much pressure the case can take before reaching its elastic limits before you have brass flow. As you can see military 5.56 brass is made harder than any commercial .223 case and also has a thicker flash hole web for added strength.

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests
http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/
 
So 270 brass is not stronger than 280 brass and there is no reason to buy a bag of 270 over 280 for loading 280 ai. Correct?

Just use your .280 brass, some cheap bastards neck down 30-06 brass to make ..270 cases. I'm a cheap bastard and 67 years old and have been reloading for over 46 years, and have never ruptured a case or had a case head separation in all that time.

So again, measure your base expansion to see what pressure it can take. Normally of the US made cases Winchester has the hardest brass, then Lapua.
 
So 270 brass is not stronger than 280 brass and there is no reason to buy a bag of 270 over 280 for loading 280 ai. Correct?

The pressure standard is determined by the action/gun, not the brass cartridge. The brass cartridge is more of a seal to hold the hot gases from leaking out. The chamber/action/bolt is what takes the stress.
 
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