Sherman Wildcats pressure limits?

[adam32]

Common sense destroys the only peak pressure equals velocity argument, who hasn't loaded two powders to the same pressure and gotten different velocities, that alone tells us there is more than peak pressure to velocity.
How many times has anyone who reloads loaded a powder, pressures it out with low velocity and low load density then without thinking why just grabs the next slower burn rate and runs it up.

Common sense isn't very common...and you know who I am and know this isn't my first rodeo.

And now you're comparing two different powders...what happened to the "all things being equal argument"?

I don't really care anymore...at this point there's no proof either way it seems.

 

[can1010]

here are some numbers using only default settings
6.5 RSAUM
147 ELDM 2.950 OAL
RL-26
59.O gr 59659 psi 2970 fps
61.0 gr 66813 psi 3063 fps
a blind man would see the case head signs are different at 7000 psi increase.
now change how the powder burns
60.2 gr 58998 psi 3105 fps
and it burns farther down barrel.
I am here to learn and thanks to some of the people here I now better understand what is happening with my own projects
THANKS GUYS

 

[Heavyiron]

I still believe in useful wildcat cartridges, the sherman and ackley are very useful toward getting magnum veloicities . You can carry one more cartridge in the magazine and have one more shot.
My next project will be a sherman on the 06 case design. Just trying to figure out what caliber.
Handloading is common sense, reading cases is not some dark, back room experiment. When cases expand 0005 you have reached max velocity.
A friend of mine kept nagging me about the 280ai being way up in pressure with the signs that i was reading. One trip to the gun club with their pressure trace ended the argument when my ammo tested at 58000 psi...!

 

[bigngreen]

Common sense isn't very common...and you know who I am and know this isn't my first rodeo.

And now you're comparing two different powders...what happened to the "all things being equal argument"?

I don't really care anymore...at this point there's no proof either way it seems.

Well, if by your reasoning only pressure = velocity then regardless of powder 60k of pressure will produce x velocity across the board and we all know at a basic level that's not how it works since pressure is not the only driving force behind velocity.
Apply that to an apples to apples case volume and you can manipulate other contributing factors and see a velocity gain, I can load the same exact load in the SAUM and SS and despite volume being exactly the same the velocities are not close enough to be inside a barrel to barrel difference. I've done two nearly identical builds in a 7saum and 7 SS and using the same lot of brass and powders performance is obviously different.

There is abundant proof all the way from the most basic level of relaoding if you don't make your mind up based on a less complete understanding of the subject. You asked if anyone had ran pressure traces and I have on some cartridges including the Sherman but you don't like the answers cause they aren't fitting your understanding. Others have pressure traces in this thread and have seen things that make a difference that you wouldn't think would and other things making a big difference that others disregard.

 

[highdrum]

I'm curious if I take a full length 7saum case, run 40° shoulder, use 0.007/inch taper, which is very similar to Richs case, it will get another 50fps over the SS cartridge. Powder capacity should go up 4gr or so to 75gr total. I've also pondered doing the same to a 7 blaser case, it would end up around 87-88gr capacity.

 

[bigngreen]

Basically that's a WSM, I've built a couple throated WSMs for the 215 Berger stretched out and it's running very similar to the 300 SS but that's my only kinda close comparison between a WSM capacity and the SS.

 

[highdrum]

Rhian I do agree, but the minimal case taper helps the case grip the chamber walls, holding more pressure in the walls, less to case head, which is where we visually see excess pressure. Holding more pressure there will save primer pockets and extend brass life. There is no free lunch, velocity comes from pressure, safely containing that pressure is what the SS cases do, in my opinion. Peterson designed their 300 norma brass to withstand multiple firings at 77k psi. Not saying people should push it that hard. But custom quality actions with properly designed cases and quality brass can shoot loads at 70k psi somewhat safely in my opinion, if they so choose to.

 

[bigngreen]

We can definitely get the brass to show less thrust related pressure signs, case swipe and hard bolt lift but the case head expands from pressure not thrust so regardless of design the unsaported case head moves at a given design pressure and there is no design variable we can change in a case to change that.

 

[MagnumManiac]

A quick calc on QL shows a 7,000 psi increase on a SAUM case with a 140 Berger equals right at a 100 fps velocity increase with everything else staying equal...100 fps isn't a small jump...about the difference between a SAUM and SS isn't it?

If this is where you are obtaining your wisdom from.......QL, then this is why you simply cannot understand how pressure works.
QL can be out on the order of 20,000psi. I discovered this when I bought Pressure Trace II software and the piezo crystals.
QL is no more than a wide GUESSTIMATE of pressure and loads, in one instance for a 264WM load, the 'excessive pressure, do not use' load was in fact 200fps slow and over 28,000psi below max pressure.

I take QL predictions with a large grain of salt.

Anyway, I'm done arguing about pressure with you, you obviously have no handle on what is actually happening in a cartridge case when the powder burns.

Bye, bye.

 

[adam32]

If this is where you are obtaining your wisdom from.......QL, then this is why you simply cannot understand how pressure works.
QL can be out on the order of 20,000psi. I discovered this when I bought Pressure Trace II software and the piezo crystals.
QL is no more than a wide GUESSTIMATE of pressure and loads, in one instance for a 264WM load, the 'excessive pressure, do not use' load was in fact 200fps slow and over 28,000psi below max pressure.

I take QL predictions with a large grain of salt.

Anyway, I'm done arguing about pressure with you, you obviously have no handle on what is actually happening in a cartridge case when the powder burns.

Bye, bye.

Nope, and I agree about QL being off. I've seen it multiple times. I'm just stating that 7,000 psi makes a bit more difference than you think.

Bye bye, fan boy.

 

[MagnumManiac]

Nope, and I agree about QL being off. I've seen it multiple times. I'm just stating that 7,000 psi makes a bit more difference than you think.

Bye bye, fan boy.

Fan boy hey?!

I guarantee face to face you wouldn't have the balls to say that to me, so I'll just say, good luck loser.

Gudentag.

 

[ruby76]

Some of this I find quite interesting. I'd like to learn more about which powders typically "pressure up" different/sooner/ later than others. I have a 338SS and with my crappy RP brass I have seen pressure signs with some powder earlier than with others and with different velocities. I'd like to learn why so I can narrow down my powder choices for a variety of reasons; case life, throat life, temp stability, efficiency, safety, etc etc. I will soon be getting Rich's ADG brass and am interested to see the difference with some of my current loads that showed pressure signs.

 

[elkaholic]

Trying to predict that can be difficult. You can have some rules of thumb but different powders can act completely different in different cases even of similar volume. A perfect case in point is your 338 SS vs my 338 Sherman. My long action acts more like what you would typically expect with the slowest powders that will max out pressure giving the best velocity. Your SS version is completely different, and in a good way. Several much faster burning powders work the best and those same powders will blow the primers right out of my long action at lower charges, even though the long action has more capacity! The only way to know is test. I've seen a different throat configuration show up in how the powder burned, and I don't mean free bore length. There are so many subtleties that I certainly don't understand, but are there! Make no mistake; case designs DO make a difference!

 

[HARPERC]

.....There are so many subtleties that I certainly don't understand, but are there! Make no mistake; case designs DO make a difference!.......

.......I confess to being slow to believe this, but too many people I consider reliable to the first order, are bringing me around!