Home Forums Reloading Big Game Rifles 30-06, 208AMax, RL17

bwinters, your boundaries are flawed. They are your unquantified opinion.

There exists a relationship between, case volume, bore size, bullet weight, distance to lands, powder burn rate, bore friction, and other factors.

This relationship is not constant. It changes with many variables. QL allows calcs with many of these variables factored in. Reloading manuals do not.

Reloading manuals factor for safety, and rightfully so.

More food for thought regarding action strength.

Compare the pressure containing capability of any front-lug action chambered in a RUM/WSM/SAUM versus the same action chambered in 308/30-06. I don't have a sectioned action in front of me, so some of this is speculating, but it should be close. Two failure paths are: shearing/failure of the lug-action interface (failure of either the lugs themselves or the action area against which the lugs bear) and failure of the chamber wall. My understanding is that comparing the RUM actions versus the '06 actions, there is no difference in action external dimensions or materials. The RUM action will have a substantially thinner chamber wall. The RUM action will subject the chamber wall to (0.550" / 0.470") about 17% more hoop load than the '06 action. And yet, SAAMI for the RUM is 65ksi. For the other failure path, the thrust area for axial load is (0.550"^2/0.470"^2) 37% greater with the RUM versus the '06. This tells me that a model 700 in 308 or 30-06 is a freaking bank vault compared to a 700 in SAUM/WSM/RUM.

As for brass, it's a gasket, and its metallurgy is subject to work-hardening. The chamber walls and the bolt face do the heavy lifting. The case head has to resist being deformed into the bolt face voids and recesses, and has to resist loosening at the primer pocket. Tough to draw an engineering correlation in required head thickness versus case head diameter, assuming equal pressure. Larger diameter case head will better resist opening the primer pocket, but will be subject to greater load resulting from the greater internal diameter of the case. I'd expect to see proportionally similar case head thickness between the head of a 308 and WSM. As for the rest of the case including the web and areas forward, don't work it too much in your reloading practices, and it will last.

One comment from earlier in the thread caught my eye regarding SAAMI maximum pressures of 25-06 and 270 brass versus 30-06 and 280 brass. Knowing what we know about manufacturing, is there a good reason for Lapua or WW to tool up to stamp out '06-family brass having differing case head thicknesses? Would you hesitate to neck down a 30-06 case to 270 and run full bore 270 loads through it?

I've done the math on relative boltface pressure long ago,


.473" case head diameter = .176 sq-in, 11,440 lbs P, at 65K psi

.532" case head diameter = .222 sq in, 14,430 lbs P, at 65K psi

Shane - my post was not aimed at you directly and was not intended to throw rocks. I too have wrestled with load data for the 30-06 - and 280 and 7RM. I offered my observations as food for thought.

I'm not sure I agree with your assessment of my boundaries but we could discuss that point. I agree a relationship exists between the variables you cite. What I am saying is that the model (QL) needs to match the acutal (your rifle's chamber dimensions) closely for modeled results to be valid. I'd think a good comparison would be modeling existing, known pressure tested data against QL. This will give some insight into the sensitivity of the variables in question.

As such, linear interpolation is similarly flawed but the use of several methods helps lessne the sideboards of the variables involved - in essence help converge to a solution in the absence of real pressure tested data.

To me, the difference in our answers is not which one is more verifiable, no singualr answer exists w/o pressure data, but what is prudent - and where do you and I draw the line. My sole point is that in my estimation, reliance on QL as the only source of information makes me uncomfortable. I'd greatly prefer my approach - linear extrapolation in combination with QL and known boundaries for specific bullet/powder combos. I find your results interesting and would like to see more results but I also reserve the right to comment w/o throwing stones. In the end you are the guy behind the gun, not me.

Good luck and keep posting.

Ok, wow, lot to digest here. But simplified in my terms for someone who might give RL 17 a try with Shane's 130 TTSX loads in the .30-06 (and I'll work it up slowly):
We are concerned about excessive pressure
Excessive pressure blows up guns
Shane's guns have not blown up
Load is not excessive in HIS gun

bwinters,

I'm not sure what your familiarity with QL is, but the thing that makes it most useful is that you can edit some of the basic inputs to match your specific rifle/components.


Some of the variables you can edit include:

seating depth
shank seating depth
bullet length
bullet diameter
cartridge length (oal)
case length
groove diameter
barrel length
bullet travel
bullet weight
cross-sectinal bore area
max case capacity


It allows you to make calcs closely tailored to your specific rifle, and ammo.

It's far from calcs for an "imaginary rifle" and "imaginary ammunition", as implied by some here who have most likely never even looked at the program.

exbiologist,

That's about sums it up.

I might add, that it has not even flattened a primer, or caused stiff bolt lift, in my rifle.

Shane, are your interpolations of pressue based on the assumption that the Alliant loads are at 48,900 psi and/or use that as a baseline for QL?................DJ

ex - feel free to load whatever you like in whatever fashion suits you. Good luck with your method, hope the results work for you in YOUR rifle.

MM - have no familiarity with QL, just the conceptual basis of using mathematical models to quantify empirical phenomenon. Looks like alot of variables can be tweaked to get the modeled results to match the empirical. Glad to see that.

I still don't see ways of adjusting the powder chamber dimensions - chamber size, leade, throating, etc. I'd bet case volume is the proxy for all of those specific variables. Curious question - does QL ask for case fired water capacity or re-sized capacity? Case fired capacity seems most logical as it more accurately represents powder chamber dimensions.

I find this type of discourse much more meaningful than throwing rocks..........Thanks.

Am also thinking that bullet travel is the proxy for everything in front of the case dimension (leade, throat, etc). Case capacity is the proxy for chamber dimension. Without actually playing with it, looks like it should be in the ballpark.

I'd still cross reference to my linear method and known data to further refine the boundaries of loads. Thanks again.

The point was Shane's response to Dj last page. Uncalled for.

As far as speculation, Shanes in shallower water than me or DJ.

But as I've said from the beginning, he can do what he wants.

dj, No. My assesment of pressure with QL is by chronographing the load, then looking at that velocity on a QL ladder chart, for a pressure estimate of that velocity with the powder/bullet in use.

I tend to agree with JB's assessment that QL does a reasonably accurate coorrelation between velocity/pressure, than it does correlating powder/pressure. That said, QL powder/velocity calcs have run pretty darn close with the 223, 308, and 30-06 stuff I've worked up over the seven years or so that I've been using QL.

RL17 is the only powder I've used where the calcs for velocity/pressure do not seem to correlate well.

QL calcs useable case volume based on editable inputs for empty case volume, and bullet seating depth (or OAL).

I've found that calcs are most accurate when the oal is entered per the length where the bullet touches the lands, even if the bullet is seated deeper. Basically the 'freebore' has the effect of extra combustion chamber because the bullet is preety much moving up to that point without any resistance other than it's own inertia. Neck tension yes, but that is reduced too since i'm using moly.




QL provides a default case volume. in the case of the 30-06 it gives 68.2 gr water. That is about what milsurp brass holds. The commercial brass I've measured holds 70-72.5 gr water, after fireforming (I only neck size).

Let's take a look at something, JFSAG..........

Sierra 168 BTHP MatchKing loads.
Sierra 5th Edition lists this as the maximum load with RL-15:
51.2 grains, and 2900ish fps
That figures a 3.285" COAL, 1-10" twist, 26" tube, Savage 110, Federal cases, and Federal primers. No moly.

Hmmm...........

Federal cases generally run about 68.0 grains of water capacity, so that's the spec I'll punch into QuickLoad.

QL calcs that load at 53,811 PSI. Having shot that load, it's mild, and the pressure spec'd is likely about right, as you can generally go a good bit above that before you see pressure signs.

Even so, let's see what changing a few parameters nets.

Use R-P brass (71.0 grains, average, water capacity), run moly, and seat to 3.385" COAL.

The exact same load runs only 44,990 PSI. That's a HUGE difference.

Pardon me for getting the slightest bit defensive after the guy [bleep] all over my thread, page after page......sheeeeesh.

It's one thing to make your point, even reinforce it. It's another thing to just carry on and on, not introducing anything of substance, just determined to have the last word.



Who knows, we may get a little bit of useful discussion out of this thread before it's all said and done.

My "go to" load with the 168 TTSXs (.2" groups at 100) is thus:
R-P brass, WLRs, RL-15 (54.0 grains), moly'd 168 TTSX, 3.495" COAL, and a 92.7% capacity load density.

QL gives the PSI numbers on that load at just a RCH over 58k PSI. The velocity estimate through QL is very, very close.

Now, run the same load through the "standard" Federal brass, no moly, at the spec'd 3.340" COAL, and you have a 102.0% capacity load, and you get 73,200 PSI.

So, WTF does this mean? Basically, what Shane's been saying. The variables that he brings into play (much longer COAL, more capacious brass, moly, generous throat geometry) all play a part in very likely making the loads he's running quite safe in his rifle.

What I'm curious is if you have tweaked the parameters to where the pressure tested load from 6.5br matches it's 54,400psi at 47.0grs with a 185gr bullet at 2701fps and then moved the powder charge up to the 50+grs to see what it says the pressure would have been.

And then with the parameters matched see what pressure 47-50+grs would make with a bullet 15grains heavier.

It doesn't mention the barrel length but if 46.0grs of Varget and a 155gr bullet is 3036fps it isn't a short one......................................DJ

A few subtle adjustments can easily make a 10K difference in pressure calc.

A lot of the guys on the 'hide running Lapua brass in match chambers with nekkid bullets are charging with 2-3 grains less powder, and getting the same velocities. The differences are real.

You don't mention the other possibility of what your test might mean, and that is that Quickload isn't very accurate in calculating pressure between different brands of brass! I've shot a couple of the same loads in Lapua, WW, RP and Federal brass and shot them in several different rifles. Velocities have been pretty close between the different makes of brass. I Certainly haven't seen any of the changes that you'd think you would see in the difference between 58K and over 70K pressure. The velocity should be a good bit higher with the same powder and bullets between 58K and 70K pressures.

I've seen Quickload estimate pressures at over 100K psi in loads that were spot on for burning rates and chronographed velocities. I've also seen primers popped in loads it said should be mild. I think it's a FAR less accurate tool than a Chronograph!.................................DJ