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.243 anywhere?

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15 years 1 week ago #2201 by donkey1984
Replied by donkey1984 on topic Re:.243 anywhere?
So in other words your saying that .243's wears out Quicker? i just want to make sure that i am understanding you correctly. also where do you work/teach at msh?

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15 years 1 week ago #2202 by weshowe
Replied by weshowe on topic Re:.243 anywhere?
Gents,

As I alluded to earlier the problem with the .243 is the ER(expansion ratio) of the cartridge based on case volume.

While the .223/5.56 will have a capacity of about 24.0 grains the .243 has a capacity of about 45.0 grains depending on powder used. Case capacity using water can be used as well, but the real problem is that you are trying to push a higher volume of hot gas down a very small bore. Which is why barrel life with a .223 is normally very good. Drive the same bullet down a bore with 45.0 grains of powder (.22/243 bore) and you will burnout the barrel in short order.
In short you are forcing double the volume of hot gas down
bore with the .243 vice that of a .223. Bad ju-ju for barrel life.

Wes

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15 years 1 week ago #2209 by a Guest
Replied by a Guest on topic Re:.243 anywhere?
Who ask I am retired now but teach part time at Motgomery Community College gunsmithing program. Also Sr. eng support for SOTIC part time. I make up barrels 3 days a week and do the special chamber jobs for Lilja rifle barrels. So who ever ask back up the line here it is.MSH

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15 years 1 week ago #2211 by donkey1984
Replied by donkey1984 on topic Re:.243 anywhere?
So a .243 barrel would probably only last about 3 or maybe 4 thousand rounds right? Thanks again for all of the info guys.

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15 years 1 week ago #2212 by a Guest
Replied by a Guest on topic Re:.243 anywhere?
It's gone at 2000 rounds.MSH

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15 years 1 week ago #2213 by donkey1984
Replied by donkey1984 on topic Re:.243 anywhere?
well scratch that idea. Is a 7mm-08 any better?

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15 years 1 week ago #2224 by donkey1984
Replied by donkey1984 on topic Re:.243 anywhere?
i figure a 7mm-08 is 1 more mm bigger in diameter so maybe it is a little easier on barrels and still has a little flatter trajectory. And i still have room in the safe for another one.

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15 years 1 week ago #2226 by a Guest
Replied by a Guest on topic Re:.243 anywhere?
The smart play on this one is to go 260 and extend the gas system 4 inches and its got good barrel life and is close to the 6.5-284. The key is to extend the gas or you'll be stuck at 2600 fps. 2800fps is much better the other way. The 708 is a poor choice on gas guns.MSH

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15 years 1 week ago #2227 by donkey1984
Replied by donkey1984 on topic Re:.243 anywhere?
alright thanks a ton for the info

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15 years 4 days ago #2251 by Scaup58
Replied by Scaup58 on topic Re:.243 anywhere?
>>> The 708 is a poor choice on gas guns.MSH

Interesting comment, care to elaborate? Not that I'm contemplating one, I'm the guy that want's to build a .22 Middlestead, but I am curious.

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