Re: 7MM-08 Barrel life
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: D_TROS</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steve123</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steve123</div><div class="ubbcode-body">I have a Rock 7mm 1-8.7 sittin in the safe waiting for me to decide what to do.I'm thinking 7x47L-nitriding barrel-28"-throating for 180's-2650 fps.Maybe 5000-6000 rounds barrel life??? </div></div>
Nice.
I'm thinking of a 7 down the road, can 7X47 get more speed on a 162/168 than a -08 happily in a short action? </div></div>
Near as I can see eyeballing it,a 162 Amax can be seated with the bottom of the baring surface of the bullet at or close to the neck shoulder junction is at max mag length for AI mags.With Alpha mags it's going to be 3/4 the way into the neck.So pretty much all the powder capacity can be used.
I'll be relying on a long barrel to get me some extra velocity but it's all conjecture at this point as to what velocities are achievable.The 6.5x47L cases are wickedly strong and <span style="font-weight: bold">handle pressures other cartridges would be giving up the ghost</span> with but will still achieve high velocity with medium loads.From what I know with 6x47L and read about with 6.4x47L,I think it'll do what a 7-08 would.Kinda like my little 6mmART40 sending a 105 Amax at 2900 fps with 30.2 grains of powder.It has less capacity than the bigger cases but it is a extremely efficient case design. </div></div>
3 things.
1) With the availability of Lapua Brass for 260, the 6.5x47 no longer has the edge of higher pressure. The simple fact is that the x47 case is smaller. Yes the Lapua brass will hold a hot load, but now you can hot load a 260 (or a 7-08).
2) at those higher pressures, the brass might be able to handle it, but pressure is pressure, and the barrels will be toasted the same. I do not believe the "sharper shoulder" is that significant. couple hundred rounds max, but the differences in barrels composition/smithing, shooting long strings, weather, etc etc etc could alse be attributed to that. Too many variables to say the one magical fix is a "sharp shoulder." More of the snake oil BS if you ask me. Does the x47 have a niche? sure, anybody who wants a lighter recoiling cal that is accurate. But the 260 is ballistically superior, even if by a small margin. And dont give me the, "well it can be loaded to a longer length" bit either. If you are worried about length/case capacity, load in the AW mags and leave the x47 in the dust.
3)Barrels are expendable. Treat is as such. If you want that amazing barrel life caliber that is also accurate, its been around for decades, its the venerable 308. But if you hot rod anything, the barrel life WILL be cut down significantly. Such is life.
YMMV,
DT </div></div>
I hope the OP will forgive my slight off topic here,Sorry R99.
I agree with you about most of the things you stated but must point out some other factors.
First off I agree that there's no free lunch.More pressure means more throat erosion comparatively but less powder being used might offset that some,neck length,snake oil shoulders,case efficiency,type of powder and burning rate of powder being used all affect throat life to some degree.In real life I think choosing a single based powder and not letting the barrel get really hot has more to do with saving a barrel throat if comparing similar cases.
1. The 6.5x47L case was designed to safely handle 64,000 psi "IIRC" from the get go.I think it's because of the small rifle primer pocket and extra brass surrounding it that makes it strong.The only experience I have is with a x47L is 6x47L so that's what I'll comment about.As a "experiment" testing and working my way up to see where to stop with pressure and to see how much velocity I could get,I shot a few 105's at 3340 fps.I stopped there for fear but could of gone higher.The primers pockets were not loose but there was a sticky bolt and of course excessive primer flow.It would be interesting to see if a Lapua 243 Win case could do the same without being destroyed.I'll say this also and shut up.Using the same lot of 800 brass I haven't lost one cartridge case yet from any kind of wear or pressure related issues in 4 years.Some of the cases I've used for load work up have been fired so many times I've lost count.
Here's some discussions and food for thought about the subject.
http://forum.accurateshooter.com/index.php?topic=2703090.0
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2368697
Anyways...I got exited about a similar project I had in mind with 7x47L and long barrel life(and long barrel)so that's why I posted.The OP's post context was about barrel life and 7-08.If I were to wager I'd say they'd be within 50 fps of each other and have the same barrel life.Anybody that can see the real world difference of 50 fps in the field needs a gold medal and a free ticket to heaven,LOL.
Expendable barrels go with expendable income.Barrel life is becoming a more of a concern daily as the economy wains.
