.308 Load Development Story from a Rookie, for Rookies

Anyway, onto something more positive....

I shot 50 rounds. 5 sighters for a 100yd zero, then 5 each at 42.0 up to 43.6 in .2 steps.

Had some ejector marks at random along the way, and a bit of a stiff bolt on one at 43.4. No tough lifts at 43.6.

I didn't adjust for elevation as the load increased. I thought it was interesting (but expected) to see them climb.

Question: based on lack of pressure signs in tempted to try 43.8 and 44.0, but I could hear the varget crunching as I seated the bullets on the 43.6. Should I carry on, or stop at 43.6??

I'm liking the shape of 43.6gr. I'm gonna load up some more at that this eve and get out again tomorrow, maybe at 3 or 400.
 
I assume this is nothing to worry about since it happened at 42.4gr (low pressure)??

I'm looking at the half moon just in front of the L in Lapua...

Yes, I know, my hands are dirty....
 
Consider 43.5, 43.6, 43.7, 43.8 with fireformed cases.

Over a chronograph anything over a solid 2700fps...... 1/3 min with as little vertical as possible.. DONE.

Tweak if interested to push into the low 3's high 2's

Go compete and have fun.

And yes, the pressures you are running ARE elevated. Yes, they are above book pressures but useable unless you continue to see more brass swipes then you may have to drop to a lower node or change powder.

Jerry
 
Gunneegoogoo said:
Is there a rule of thumb on what % of cases with swipes are OK?? Seemed to be pretty hit and miss today.
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Essentially, ZERO cases should show that brass swipe BUT you are only forming cases and that can move the brass into positions where this can show up.

IF, the next firing also shows brass with this issue, pressures are simply too high.

Let's see what happens on your next trip.

Jerry
 
Put another 20 down the tube this aft.

I went to 2.080 BTOL instead of 2.100 cause I thought about it and I may have been jamming into the lands at 2.100.

Did 43.5-43.8, with the chrono. 200yds, little wind.

The percentage of ejector marks steadily increased to 4/5 at 43.8, but look at the group!! Now I'm good and confused!!! No primer signs, no hard bolt lift. ES of 33, mean V of 2710.

I was hoping to get some more speed out of that long barrel. Was I wrong to hope for that??

I have 30 pieces of virgin brass left to FF. I may go back to 42 with the new seating depth. Once all 100 are fired I'll give them al the royal work over....

Opinions on whether I should persist with the 43.8 given the group it gave me?? I'm thinking of making up another 5 at 43.8, and then looking for another node lower. I'm hoping once I work over this first set of brass with turning/annealing, etc it'll help.
 
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Believe or not, long barrels really don't offer much speed with a limited case volume like the 308. why I suggested you look for the node a 2700'ish fps... you found it. And it can shoot very very well.

With FORMED cases, I would check back with the current seating depth from 43.6 to 43.9gr in 0.1gr increments. The outs may just be the variance in the forming of the cases....or driver error or....

Thick case necks would be another reason for the outs... try and drop a bullet into the fired cases. See if any give resistance to the bullet falling in. I would turn all fired cases to 12 thou before further testing.

The load IS hot... no doubt about it but that is pretty typical of F class loading. The swipes on the case head is problematic so I would look for any burrs or sharp edges on the bolt face. if the ejector was removed and there is a hole there, it can cause these marks very easily.

if the problem gets worst with formed cases, you will have to consider another powder.

This may be blasphemy but I do not like nor use Varget in FTR loading.

More tweaks but you are getting closer.

Jerry

PS you have noticed pressure signs at 2700fps.... just think, there are some who think 2850fps has "no pressure". Because you don't see it doesn't mean it is not there.... but that is another gripe for another time.
 
Thx Jer.

Your comment about 2850 is exactly why I'm asking!!!

Seems there's lots of different thoughts on what's safe, what's a BAD pressure sign, etc.

I'm gonna do up the other 30 cases, 5 more at 43.8 and see if that sweet spot persists, and with the rest go back to 42 and chrony it.

-J.
 
There is a small population of shooters who consider Lapua SR palma brass to be a really bad and dangerous component.

Not that the brass is "bad" per se but that it is overly strong. This allows shooters the illusion that what they are shooting is "safe"... The brass masks alot of typical pressure issues. When things do show up, they are well into proof pressure loading.

Not good for their actions, not safe for those beside them.

Until pressure trace testing is mandated, crazy super speeds will continue as many custom set ups masks pressures so well, "nothing to worry about".

Do some research into the pressure ratings of SAAMI and action testing by White labratory... very interesting and eye opening stuff. I have actual fired cases marked as proof pressure test cases.... Yep, not a single pressure indicator on the body and from a "soft" US brass manf.

Why a chronograph is your friend.... As long as you keep loading pressures in the "magnum" range, with modern components, it is all very safe as all is designed to live in this environment. When you start loading north of 70k psi towards 80k psi, things will eventually go wrong.

Jerry
 
There's ways to get really good speed without going too overboard on pressure, just as its not that hard to get crappy speed and over pressure. But it can definitely get some into trouble if not done right.
Now I kinda want to buy a pressure trace system...
 
Without going to a piezo based system, a quite accurate estimation of max pressure can be gained from chronograph data. That is, if you see that the brass is moving- ie shiny arcs on the casehead, primer pockets loosening, or sharp primer edges (though this is an inaccurate method), and also your velocity is 'pleasantly higher than expected' or higher than what the Internet average is, then you can be quite sure that your pressures are north of 60kpsi.

Load safe and learn to read the wind. It's better that way. If you want less wind drift, shoot something other than a 308w. Otherwise it's asking water from a stone.
 
Gunneegoogoo said:
Can someone tell us about this pressure trace thingy??
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A strain guage is attached to the barrel and ammo fired... compared to a known pressure load, it let's you calculate the pressure and pressure curve of the new load.

Google internal ballistics for more info.

Given we are using very similar components, something like Quickload can also be a very good aid... not perfect but you can have a good idea on which side of redline you are.

But in the end, feedback from what competitors are using is useful simply by the shear volume of results over time. If the vast majority run XYZ at 2700fps, and you suddenly get 2800fps with the "same" stuff... something is off and it could be as simple as the Chronograph.

There isn't any free lunch and it has all been tried many times over in search of that holy grail.... the irony, loads that are way over magnum pressures are usually really fussy to keep in tune and when they go out of tune, it is spectacular how lousy the grouping becomes...and this can occur from morning relays to afternoon relays.

You see a growing number of shooters using Tuners for this reason.

So, even with the possibility of extra speed, smarter competitors are loading to the magnum pressure node. Not fancy, but accurate, stays in tune (usually), doesn't wear out brass... and another 100fps is not going to save you when you are facing several MOA shifts in wind speed and direction.

Assuming you will be shooting at Nokomis, if the winds are high, it helps to calibrate the lean of the cows to the number of targets you hold over.

Fun times....

Jerry
 
ya.... Our winds are second only to Lethbridge!!! It's been especially bad this last 6 months.

Is there ever a wind limit were a match his held off, or is it "shoot no matter what??"
 
Here's a problem I wasn't expecting....

My cleaning rods won't make it to the muzzle of the 30" barrel with a bore guide in....

I'm reading a bore guide is an absolute must.

Suggestions?
 
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