Overgassing in hot weather temperatures?

[T2C]

Were your Carbine Barrels Stainless Steel also?

No. The Colt barrels, and others, were chrome lined. The carbines get run hard for about half of the barrel life. Heat is an issue.

[Spooky1]

No. The Colt barrels, and others, were chrome lined. The carbines get run hard for about half of the barrel life. Heat is an issue.

Oh ok, now I understand. Thank you.

[1168]

SPECIAL FEATURES
Our 5.56 mm F1 ball ammunition is manufactured at
Australian Munitions’ Benalla munitions facility and is
currently in use with the Australian Defence Force (ADF) in
the Austeyr individual weapon and F89 Minimi light support
weapon.
Australian Munitions’ 5.56 mm F1 ball ammunition employs
a specifically designed single base propellant with very low
temperature coefficient of ballistics to ensure velocities and
pressures remain consistent within variations in ammunition
te

That briefs well, but even military ammo suffers from temperature changes. https://www.psmagazine.army.mil/News...-affects-ammo/

[mRad]

I should have posted this "mate"=http://www.australian-munitions.com....A4-2pp_web.pdf

Mostly marketing. Notice they don’t go into specifics. The Australian powder marketed by Alliant here in the US that is said to be temp stable has more than double the temperature sensitivity of Hogdon Extreme series, but it is wolds better than any ball powder.

So at the end of the day, “temperature stable” compared to what?


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[ta0117]

So I shot with my friend again today, and though he let me shoot his rifle he doesn't want to switch BCGs, thinks there's some kind of risk of not headspaced together or something. Either way, I loaded the usual Wolf Gold WM193 and shot my rifle and his rifle back to back. Again I can notice a difference, with his feeling softer, despite also being midlength 16", with larger 0.078" gas port, and carbine buffer. The DD's 0.073" gas port and H buffer feels harsher, I'm throwing brass at about 2 o'clock, his gun throws brass at 3-4 o'clock. In fact his rifle firing WM193 feels like my rifle when firing PMC Bronze .223.

I'm not complaining because I think it's some unmanageable recoil. I'm more confused and annoyed why my rifle feels more gassy even though the paper specs should say otherwise. Could it be that his BCG is not as gas efficient? Are 16" midlength DDs known for being overgassed? I've searched around, but as far as I know their 10.3" were overgassed, but nothing on the 16" midlengths.

[lysander]

So at the end of the day, “temperature stable” compared to what?

When a military contractor states their propellants are “temperature stable”, it means the military finds the "instability" within acceptable limits.

WC846 and WC844 are “temperature stable” as far as the US military is concerned, some civilians might disagree.

[mRad]

When a military contractor states their propellants are “temperature stable”, it means the military finds the "instability" within acceptable limits.

WC846 and WC844 are “temperature stable” as far as the US military is concerned, some civilians might disagree.

Yes, I understand what military considers acceptable. And it isn’t very stable. Which is why I said, “compared to what”. The claim in the link is meaningless.


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[lysander]

Yes, I understand what military considers acceptable. And it isn’t very stable. Which is why I said, “compared to what”. The claim in the link is meaningless.

“Compared to what”?

The Australian Defense Minitsry's requirements for propellant stability, obviously.

And, "the claim in the link is meaningless," is incorrect, it means that the Australian Defense Ministry finds their propellant temperature insensitive.

BTW, they are using IMR 8208 XBR, which is a very stable propellant.

[mRad]

“Compared to what”?

The Australian Defense Minitsry's requirements for propellant stability, obviously.

And, "the claim in the link is meaningless," is incorrect, it means that the Australian Defense Ministry finds their propellant temperature insensitive.

BTW, they are using IMR 8208 XBR, which is a very stable propellant.

It doesn’t actually give us data. It’s a claim.

8208 is fairly stable, but there is far better powder for temp stability. I find it strange they aren’t running a true ball powder.


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[opngrnd]

It doesn’t actually give us data. It’s a claim.

8208 is fairly stable, but there is far better powder for temp stability. I find it strange they aren’t running a true ball powder.


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Which powders are more stable? I've always thought of XBR as one of the best off the shelf options commonly available. (Not that it's common anymore.)