Let's talk about High pressure catridges. taking the 308 win to 62000psi (saami max)

[FredHammer]

Naw, running those bullets is no different than a 308 bullet in a 299 or 298 bore, running high speed. In subsonic mode is where it gets interesting.

Interesting and good to know. Do/did you back off the charges a little?

 

[ARShooter91]

Yep, military 6.8X 51 is the head stamp on the case ...civilians have the 277 Fury in 2 varieties, all brass and hybrid SS heads ...not likely that you'll whittle some out on the lathe.
But you can buy them, not always readily available, like most everything else. But they can be formed to 308, 6.5 CM, 358 win, as I have, or any 308 based cartridge, 277 length or shorter. They appear like these with the marked ladder load for the case. Yep some 308 loads contain 55 grs of powder, they have more capacity than brass cases. Live and learn...the cartridge world is changing. Better powder blends are needed to make these really go like the 277 powder used in military cases. The military is running machineguns with these 80,000 psi loads.
The 6.5 CM will run 140s at 3156 fps 24" barrel and the 308 will run 200 SMK 715 BC to 2952 fps. And 168s to 3256 fps.in long barrels, and 4000 ft-lb of energy out of a 308 case.
So who needs the big old full brass style magnums? Big magnums could be much smaller in size and be more powerful, in hybrid form.
Similar performance less powder and brass...if all this moves forward. Or dies on the vine... but the 277 hybrid case and 80,000 psi is the real deal.
These cases will take more than 80,000 psi with ease... so be careful with any endevor you pursue, in the hybrid case arena.
For educational purposes only, enter at your own risk.
Definitely not a place for morons, and nothing can beat the Hornady’s "New" lines of ARC. & PRCs ..it says do on the box, and in their advertising, & ballistics hype talks, propaganda, & charts...but none of its new or improved...but the hybrid case and 80,000 psi IS...

Have you shot enough of these to see the effect on barrel and bolt life? Sounds good but does it turn a 308 into a 243 or 22250 concerning barrel life

Also do you shoot suppressed?

 

[Gunfighter14e2]

Interesting and good to know. Do/did you back off the charges a little?

Yes 5%, then just worked up as normal. The 123gr ak47 copper flashed steel core rounds shot great, in a 308, as did the same type of heavy 54R projos in a 300wm. The 123's in a 300wm loaded to afterburner, are worth having around.

 

[45-90]

I fully understand progress, and why the military is wanting more reach. Not being up for a knife fight or lacking the skill sets to work closer, yes more reach would be comforting.

It defeats Russian body armor...you can buy the civilian version, semi auto, for a mere $8000 or $9000, Plus $3 per shot ... if it were available...but I'm not sure what varieties the public gets. A person has fired the ammo in his 277 Fury and it was 150 faster than printed on the box from a 16" barrel.

 

[45-90]

Have you shot enough of these to see the effect on barrel and bolt life? Sounds good but does it turn a 308 into a 243 or 22250 concerning barrel life

Also do you shoot suppressed?

I do not run a suppressor, but you can buy the civilian version of this rife, in semi auto with a suppressor installed...the only way it comes. Very expensive and so is the factory ammo.
They also have a special bore treatment, Sig says is good for 12,000 rds ...(sounds like Hornady) they have to meet set military standards for accuracy, and velocity, same as any military round...It's a military weapon. So one day it will be as cheap as 5.56 or 7.62...only better.

 

[Gunfighter14e2]

It defeats Russian body armor...

Russian body armor does not concern me, one bit. Those who made/make it an issue, concern me though.

 

[ARShooter91]

I do not run a suppressor, but you can buy the civilian version of this rife, in semi auto with a suppressor installed...the only way it comes. Very expensive and so is the factory ammo.
They also have a special bore treatment, Sig says is good for 12,000 rds ...(sounds like Hornady) they have to meet set military standards for accuracy, and velocity, same as any military round...It's a military weapon. So one day it will be as cheap as 5.56 or 7.62...only better.

Yeah I mean necking up to a 308 and not significantly increasing powder charge says barrel life shouldn't be too bad. Million dollar question is what does 15k additional pressure do vs 15gr more powder.

 

[45-90]

I got to find the post, but if I understood it correctly, someone was using 277 fury cases, with the stainless case head, and getting high velocity with 30 cal bullets in the modified cases. (Maybe it was @45-90 ?)

Not exactly a 308.
But maybe those cases can be made for 308 so that 70,000 psi or higher is ok?

Got to find that post…

It was me, and the cases can be made in 308 easily...and 6.5 CM, and 358 Win as I have done...other calibers too.
It's been discussed on how it's easily accomplished...and ya don't have to go full 80,000 psi, to see an improvement. Ain't gonna explain it over and over, took pictures to show what I used...these are 6.5 CM neck turned and finished, needs OAL trim...and 308 fired cases, plus a 358 Win case necked up. I like Lee resizing lube for the task as shown.

 

[45-90]

Swaging a bullet down "in barrel" to obtain a higher BC?
I swage .458" jacketed bullets to .452" all the time plus a bunch of others..
Example 450 bushmaster 16 twist 500 gr jacketed SP 458 to 452 in a die... not in the gun...plus they probably wouldn't chamber.
I swage them down before shooting...in a Rockchucker press, lube em up run through the cheap available Lee bullet sizing dies, or make your own or polish them to any size ya need.
50BMG takes more pressure when sizing, so there moved to an arbor press... the rest a piece of cake.

 

[redneckbmxer24]

Wait so there’s actually people who don’t start their testing at max and push 3-4gr above? Weird.

 

[brianf]

I think I’ve read most of this

Everyone talking pressures/numbers.

There is no way to actually know the pressure unless your are sending it out

You can run numbers in programs etc but you have no way to know if it’s correct. They should be used as a generic direction.

Additionally pressures are not linear. It’s not a nice smooth line. It’s relatively linear until it’s not and then it’s a “exponential increase”.

And once you increase enough “thinking you know the visual signs”, you might have lug setback of a few thousandths. That then snowballs to more pressure issues.

Pressure trace is pretty good but even the inventor says it’s not accurate above 70 if I remember.

For real testing each shot costs about 3-500$ depending on the sensor costs and other factors.

All in all don’t think your rifle is special or your chamber, barrel, brass, primer, loading technique is special. That will only get you in trouble sooner or later.

If you magically are getting more velocity than everyone else..your WAY over pressure.

Just my 2 cents

 

[The Spirit]

in my thinking. Basically all began with the the 762 Russian. That goes from 7.92 to 7.62. In this case from 308 to 0.296. both the same area reduction

 

[Gunfighter14e2]

Additionally pressures are not linear. It’s not a nice smooth line. It’s relatively linear until it’s not and then it’s a “exponential increase”.

And once you increase enough “thinking you know the visual signs”, you might have lug setback of a few thousandths. That then snowballs to more pressure issues.

This.
Long ago messing with a 7mm rem mag I went from no pressure signs at all, to blowing a primer w/ 1/10 of a grain more of IMR 4831 pushing a 175. Thinking I just weighed the powder wrong, same thing happened again. Dropped 1/10 and everything looked normal again.

I fully understand moving forward w/ technology when there is a defined or perceived need. However it matters little what troops are fielded with if they can't basically shoot under stress, in the first place. Then you have that whole concept of a 22 behind the correct ear/s or laced food would stop wars before they were started, but that does not fund XYZ pocket's or make work for all those who eat from producing all logistics, tending the wounded, or dead body's, ect.
OK, time for me to go, as I see the white coats coming to take me for morning treatment. One is a 11/10 top Heavy Asian chick, being crazy has its perks.

 

[E. Bryant]

Does the force which really breaks barrels or is it dangerous?

If you do not understand the various mechanisms by which over-pressure rounds might damage a firearm, then you need to do a lot less posting and a lot more reading (starting with some basic mechanical engineering texts), or stick to factory loads.

 

[B y r o n]

What pressure do you think folks are getting when they are reporting heavy bolt lift, stuck bolt, blown primers etc.?

 

[45-90]

Wait so there’s actually people who don’t start their testing at max and push 3-4gr above? Weird.

Yep...kinda, sorta, ..in a way... but almost not really...but my 300 WM has to be faster than my 308..
So I gotta alter the 300WM load so we can add more powder to the case, and beat the 308.
Then mark the top load cause I know it's over pressure...even predicted by QL with all the parameters plugged in.
When tested the velocity is really high, 3280 fps for a 200 gr SMK in the 300WM.
Yep, left a light ejector mark and stiff bolt lift. Primer looked ok, but pretty flat. The case had already been fired several times.
So, deprimed the case, the primer pocket was now too loose... as figured when gauged. Definitely past max with all the loading parameters pluged in, even with the extra long cartridges to add more volume to the case.
Wildcats no load data at all, limited powders, reminds me of the old PO Ackley experimental days. I have seen a local guy do this...well I ain't gonna say, cause some will follow, that dangerous procedure.

 

[The Spirit]

I think that's very good idea. I guess that this could be better than 300 win mag, Because it would raise the bc and throwing lighter bullets, and you just need to change the barrel, because you already have the handload tools for a 308

 

[sinister]

The international Palma shooters have long built 308 Winchester rifles to push a 155-grain Sierra boat-tail match bullet fairly fast out of a longer 28 to 30-inch barrel. Typically that's out of a specialized single-shot action (Stolle Panda, Stiller, Barnard, Nesika, RPA, Paramount, etc.).

Start with a long-throated tight-bore .298" barrel finished at 30-inches. Long-load a Sierra 155 Palma bullet (or perhaps a 155 Lapua Scenar) over 46 grains Varget. That bullet will go close to 2900 feet per second. Don't know the pressure numbers but that's with conventional brass (not hybrid) cases.

 

[45-90]

Depends on the chamber... when you are pushing the pressure.
I FIRED 17,000 match loads of 308 Win to 1400yds many yrs ago.
Depending on barrel and chamber up to 48.5 gr Varget, for awhile..
Varget was $112 for 8 lb jugs...and discount when 3000 155 Lapua bullets were purchased, got some for 26 cents ea.
Bought my own reamer to do all the rest of the barrels. So 47.5 to 47.7 gr of Varget 27" finished match barrels 2975 to 3000 fps, Lapua brass, Lapua 155s, Fed match, & Varget. Nothing changed after that.
.298", .299" bores were common...but I went with .300" nominal, some 13 twist, I stuck with 12 twist, maybe an advantage at 1400yds...maybe?
Brass would last 40 reloads, with minimal sizing, no annealing.

 

[357Max]

The international Palma shooters have long built 308 Winchester rifles to push a 155-grain Sierra boat-tail match bullet fairly fast out of a longer 28 to 30-inch barrel. Typically that's out of a specialized single-shot action (Stolle Panda, Stiller, Barnard, Nesika, RPA, Paramount, etc.).

Start with a long-throated tight-bore .298" barrel finished at 30-inches. Long-load a Sierra 155 Palma bullet (or perhaps a 155 Lapua Scenar) over 46 grains Varget. That bullet will go close to 2900 feet per second. Don't know the pressure numbers but that's with conventional brass (not hybrid) cases.

Haven't ever tried any of those Palma bullets. Recently @GBMaryland was kind enough to give me some 160gr Warner Flat lines to try.
First outing with them I was pretty impressed. Warner's load data listed about 30 powders & CFE223 was near the top for speed. Oddly Lever was not on the list, so of course that's what I used. CFE & Lever are pretty damn close with the edge going to Lever with regards to speed & forgiveness at the upper end.
Anyway I ran 3 loads in some Virgin primed MAI (Norma) 308 LR brass. Neck mandrel &od/id chamfer was only prep.
26" Osprey 10 twist 308 Win PVA barrel.
160 Flat Line loaded 2.954" = .018 off lands. G7/.278 G1/.556
Primer ?
Lever
47.4 = 3002 SD(P) 5.8
47.8 = 3024 SD 10.4
48.2 = 3055 SD 15.1 Primer flat, but no cratering, no hard bolt lift. SD headed up. Pockets tight.
None of the above are compressed loads 48.2 is close.

I'm happy with 3000

What I've noticed with Lever in 308 is that when you find it's happy place the burn signature is super clean.

Below pic of 47.4 Lever 160 FL load.

The 3 on the right are the 47.4 Lever (pretty much zero carbon), compared to the 3 on the left 45.4gr RL 15.5 with 177 smk @2760.

Edit: Here is a snip-it of Warner load data for a 26" barrel with the 160's
Notice I'm loading .100 longer. The Norma case capacity is on the smaller end of the spectrum for 308 though.

 

[brianf]

Haven't ever tried any of those Palma bullets. Recently @GBMaryland was kind enough to give me some 160gr Warner Flat lines to try.
First outing with them I was pretty impressed. Warner's load data listed about 30 powders & CFE223 was near the top for speed. Oddly Lever was not on the list, so of course that's what I used. CFE & Lever are pretty damn close with the edge going to Lever with regards to speed & forgiveness at the upper end.
Anyway I ran 3 loads in some Virgin primed MAI (Norma) 308 LR brass. Neck mandrel &od/id chamfer was only prep.
26" Osprey 10 twist 308 Win PVA barrel.
160 Flat Line loaded 2.954" = .018 off lands. G7/.278 G1/.556
Primer ?
Lever
47.4 = 3002 SD(P) 5.8
47.8 = 3024 SD 10.4
48.2 = 3055 SD 15.1 Primer flat, but no cratering, no hard bolt lift. SD headed up. Pockets tight.
None of the above are compressed loads 48.2 is close.

I'm happy with 3000

What I've noticed with Lever in 308 is that when you find it's happy place the burn signature is super clean.

Below pic of 47.4 Lever 160 FL load.
View attachment 8329615

The 3 on the right are the 47.4 Lever (pretty much zero carbon), compared to the 3 on the left 45.4gr RL 15.5 with 177 smk @2760.
View attachment 8329616

Edit: Here is a snip-it of Warner load data for a 26" barrel with the 160's
Notice I'm loading .100 longer. The Norma case capacity is on the smaller end of the spectrum for 308 though.

View attachment 8329617

What kind of accuracy did you see with the 30.

Couldnt get them to shoot that well

Would not stay below .7 or so at 100

The smaller stuff shot much better /groups

 

[357Max]

What kind of accuracy did you see with the 30.

Couldnt get them to shoot that well

Would not stay below .7 or so at 100

The smaller stuff shot much better /groups

I was just looking for pressure/speed, but all were under 1”.
The 160FL look promising.
Not spectacular & IIRC the 3000 load was best.

Next time out I’ll trying seating depth from jam to -.120 in .030 steps.

I’ve found the solids can be picky. Haven’t found an accurate load yet with the 178 PVA Seneca’s.