Teach me about overbore cartridges

[HARPERC]

It always makes me smile watching the .264 Winchester Magnum turn into a conservative choice.

 

[thwatson2]

Overbore is when more powder is used then is burned, therefore lots of unburned powder blast down the throat. Over time it takes its toll

 

[MerlinMc]

I have at least 2 Blaser R8 barrels that are overbore. One is the 26 Nosler, a 6.5mm based on the Jeffery/RUM case and the other is a 22-243. Both are very accurate and hard-hitting for the caliber. These are hunting barrels and the only range time they see is to make sure they are still zeroed. In terms of number of rounds, neither of these is going to last long. In terms of time, they will both last years. If one or both barrels burn out before I do, I'll have another made.

For trips to Africa, I usually bring the 26 Nosler barrel and a 375 H&H if hunting DG. I have shot lots of game with the 26 Nosler, including some very large PG, and it has worked very well. None of my barrels are braked. I would love to have a 375 RUM someday, but that one may have to be braked.

In terms of the R8s, I love the system. It has worked really well for me--accurate, reliable, comfortable to shoot and convenient to have more than one barrel on a trip.

 

[MerlinMc]

Will also mention that I had a R8 257 Wby Mag barrel for awhile. It also shot great and worked well on deer here in NA. Sold it because I wanted to switch to 6.5 (also shoot the 6.5 CM in addition to the 26 Nosler) and because it was a standard weight barrel. All of my R8 barrels are now semi weight.

 

[redleg1013]

To the point of the thread: to teach about overbore.
This, while drawing an arbitrary line, did the best when I was first reading PO Ackley's work.

You are being redirected...

Essentially, you're going to take the H2O case volume and divide by the bullet diameter in inches.

The other thing that I've learned about the "barrel burners" is that a lot of competitors use them, and the strings of fire is what does the majority of the damage. If you were to subject your rifle barrel, continuously, to the heat and pressure it endures while firing, it would last for just over one second, which thermodynamicly makes sense, as heating is not a linear increase, but logarithmic. Sorry, starting to wade out into the weeds.

I would think, given those parameters, a 7-08 might be worth looking at.

 

[JMW67]

I was looking at some available barrels and the 7mm blaser mag seems interesting ammo or brass may be tough to get though

 

[montana west]

if you hand load go 6.5/06 . better than the IMP and your barrel will last a long time / your can get 3000 fps with a 140 bullet. It will for sure = the 257 weatherby in killing power . and you can never have a problem with brass 270 win trimed and 25/06 just necked up. reloader 25 26 and irm 7838 --Hodgdon h1000 will make her hum.

 

[MerlinMc]

The other thing that I've learned about the "barrel burners" is that a lot of competitors use them, and the strings of fire is what does the majority of the damage. If you were to subject your rifle barrel, continuously, to the heat and pressure it endures while firing, it would last for just over one second, which thermodynamicly makes sense, as heating is not a linear increase, but logarithmic. Sorry, starting to wade out into the weeds.

This is a useful trip into the weeds. How barrels get used has a lot to do with how long they last.

 

[Wv shooter]

This is a useful trip into the weeds. How barrels get used has a lot to do with how long they last.

It always makes me smile watching the .264 Winchester Magnum turn into a conservative choice.

I also am a huge fan of the 264WM been loading and shooting one now since 1972 have owned 7 over the last few years used them on ground hogs and deer Great little cartridge

 

[beretzs]

I have a Blaser R8, which is a multi-caliber rifle. I currently have a 30/06 and my next cartridge will be something fast and flat.
As I am researching calibers I'm learning more and more about overbore rifles and how they can blow through a barrel within 800 rounds or fewer. The question I have, as I try to pick a round, is what causes the rapid deterioration of the barrel? Is it velocity of the round or the shear amount of power that is ignited? In the long run I am looking for performance first but If I can have both then perfect because the barrels run about $1,200.
The calibers I have considered thus far is:
6.5x284
Nosler 28
Nosler 27 (new)
264 Win Mag
270 Weatherby

My shooting will mostly bee Midwest deer but want to be ready if an elk hunt comes up.

I'd guess at least 1500 rounds with any of those you listed. As long as you aren't hammering it with piles of rounds at one sitting you'll get a pile of hunting from any of them. If you like to shoot 100's of rounds per year with the rifle I'd still suspect you'll get a few years out of it with decent maintenance.

 

[MerlinMc]

Have you considered the 270 WSM as an alternative to the 270 Weatherby?

 

[Bill Norton]

I have owned a blaser since the late 90s. And a R8 since 2009. Great guns but one thing to remember. They tend to like factory seating ...standard OAL. I had 8 barrels for my R93..most were fabulously accurate. The 257 especially a true one hole rifle. It loved 100 grain bullets. I also had a 264 win. It was awesome 3/4 MOA with **** near everything you fed it....now on the flip side. The 6.5-284 in my R-8...while fabulously accurate with 100-120s. It was 1/2 to 3/4 with 143 ELDs but 147 it was lackluster. The 9.3x62 barrel was quite possibly the most accurate barrel I ever owned. For a bigger bore--a true one hole rifle. Enjoy your R8. I gave up on blaser when they started poking my eyes out on scope mounts,the first set I bought were around $200 the last set was $500. Great accurate system that you do not have to tune that much--and they flat out work. The are also great to travel as they takedown--the first pic is of my first R8 in a 30-06 simi-weight and a last light Gemsbok , next is my wife with my R93 257 WBY in Africa . Out of the list you gave and my experience with Blaser I'd go 264 win mag. Again Enjoy!

Thanks for all the advice. Did you have a 264wm in an R8? Custom barrel?

 

[Aoudad shooter1975]

No mine was in a R93...i had a 6.5-284,30-06,338 win mag, 9.3x62 in a R8--just figured they still made a 264 win mag

 

[MerlinMc]

No mine was in a R93...i had a 6.5-284,30-06,338 win mag, 9.3x62 in a R8--just figured they still made a 264 win mag

Looks like no .264 WM made by Blaser for the R8. Price for a custom would be about the same and one could get the exact length, twist, threads, flutes/no flutes, etc.

https://www.blaser.de/fileadmin/media/pdf/Kaliber-UEbersicht/BLA_PL_EN_Kal_R8_2019-05-07.pdf