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December 23, 2011

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Chuck

Actually, it's been judged that rifle barrels last about 5 to 5.5 seconds before accuracy is sufficiently degraded to warrant replacement. Computing that is a bit complicated because in the process of determining the total time each bullet is in the bore its acceleration must be figured in, and it accelerates the entire time it is traveling from chamber to muzzle. Just because the bullet exits the barrel at x feet per second doesn't mean its entire barrel time may be computed using that figure. If one did use that figure, however, and also assumed the upper time limit (5.5-6 seconds) one's estimate of barrel life wouldn't be off by much.

sDee

Clearly the .300 Hawk is very energy efficient. Energy efficiency reduces climate change. Sure, Hawks are expensive and they won't work in guns we already have, but we cannot wait for the market to sort this out. The government must take action to save the planet.

I demand legislation to:
(1) ban all other energy wasting .300 & .308 cartridges
(2) provide federal subsidies to make .300 Hawks cheaper to buy
(3) offer tax credits for rechambering or purchasing new barrels

Now don't get too impatient. We'll need to give the lobbyists and politicians time to invest in some Chinese ammo plants to crank out the .300 Hawk using cheap toxic powder.

john jay

sDee:

a little smile creases the part beneath my nose.

laughing.

an able commentary on the state of the world in any number of ways. smiling, ruefully. very able.

personally, if i get to be dictator i will simply assert that all cartridges save the .280 british and the 7mm remington magnum, and the 6.8mm remington spc be banned.

to heck w/ patience.

render the lobbyists for heating oil, and screw the chinese.

merry christmas to you and yours, and a prosperous new year to you, sDee, and many happy returns.

thanks for the read, & thanks for the comment.

john jay

john jay

chuck:

with regard to average duration of the bullet in the barrel, i agree in general with what you say.

with this caveat.-- and, that is, that is "depends" a bit, "depending" upon the cartridge. "overbore" cartridges shooting a long for caliber bullet can use all the barrel they can get to squeeze out the last little bit of velocity. i wouldn't think, for instance, that in terms of velocity that a 28" barrel on a 7mm mag would be "wasted." on the other hand, a .308 winchester really doesn't need much more than an 18" barrel to get most of the velocity from any given bullet, ... , any gains from appreciably longer barrels are pretty marginal.

and, while what you observe about velocity in the barrel is in the main pretty true, but it doesn't take the bullet very long at all to gain most of the speed its going to get, that being a very big reason that pressure in the barrel and the chamber fall off pretty quickly as the bullet accelerates down the barrel.

but, in the main, i should think your observations pretty much hand in hand in mine, and i will admit that i didn't press the issue of overall time as much as i might have, because i didn't want to run into "the great wall of incredulity." i was full expecting that if i got any comment at all, i would get, "but uncle fred's been shooting the same rifle for 35 years now, and it's o.k."

i agree with you, very much in principle. measured in terms of "real time" exposure to all that goes on in a barrel in the very brief duration of a rifle shot, it does take very much time at all to destroy the utility of a barrel in terms of peak function. 5 to 10 seconds will do it.

it has been remarked in many places that loading manual technicians had very had times researching loads on the .264 winchester magnum, because they tended to wear out barrels in as few as 500 rounds of ammo.

500/1,500's of a second, or even 500/1,000's of a second, cumulatively speaking, is not a very long time.

at all.

john jay

p.s. thanks for the read, and thanks for the comment. it is much appreciated.

and, merry christmas and happy new year, to you and yours.

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