Need some seasoned advice

[Texas10]

Not familiar with the Deep Curls, Darkker, are they a monolithic?

I think this is the first pressure trace of a SEE event that I have ever looked at, and would love to hear your educated and experienced opinion regarding the factors that might have led to the event. Did the bullet outrun the pressure wave for some reason, moly coated perhaps?

Inquiring minds would like to know.

[SageRat Shooter]

I have a 30-06 and shoot the 168 Barnes TTSX. I use H4350 and seat the bullet @ .05 off the lands. Barnes bullets like a little more jump then others. Just something to try for seating depth.

[darkker]

Not familiar with the Deep Curls, Darkker, are they a monolithic?

I think this is the first pressure trace of a SEE event that I have ever looked at, and would love to hear your educated and experienced opinion regarding the factors that might have led to the event. Did the bullet outrun the pressure wave for some reason, moly coated perhaps?

Inquiring minds would like to know.

No, not monolithic. They just have a different construction from classic bullets. I'm suddenly at a loss is those are the hybrid plated animals, or use a different density core lead; either way they generate different pressures and shouldn't be used with load data for classic bullets.

I've got a few traces where we've caught some SEE's. Never had the.... Guts.. to take it as far as Charlie Sisk. Between my own testing, Charlie's work, and a friend who used to work at one of the arsenals; the presumption is that the bullet out-paces the expanding gas for one reason or another. Then either stops or slows enough for the powder to build enough pressure to re-ignite properly/pressure wave to catch up. When it slams into the base of the bullet you get a massive localized pressure shock; and one of a few things happen:
1) you get lucky and no damage
2) you "ring" the barrel as localized plastic deformation happens.
3) you blow the barrel off at the site of plastic deformation (what Charlie got good at doing).

So X bullets start off as dead-soft copper, then get heat treated to "toughen" them up. This is why they tend to have a higher velocity requirement, and due to the "sticky" nature of them, now have relief groves cut in them. This friction difference will also different pressures(as does the Deep Curl).
As far as creating the SEE, there are a few classic ways.
1) use heavy bullets with the wrong powder speed.
Powders aren't a fixed linearly burning thing, and if you get carried away, you can slow proper combustion rates as you (for explaining) create a vacuum.
2) Use a progressive powder outside it's happy pressure window. In the Creedmoor RL-17 is progressive burning, and Superformance is extremely so. Those without velocity disease really have a true gift in that powder. You can run 10-15,000 psi off SAAMI max, and only give-up 50-75fps from max pressure loads. But when taken outside of it's pressure range, gets wild quickly.
3) usual suspect cartridges.
The 243 & 7mm Rem mag are very well known in the industry to have random unexplained pressure excursions, which get aggravated by heavy bullets and slow powders.

Cheers

[Ryfulman]

Load tuning is capable of making any load consistent,as long as the powder is appropriate for the bullet weight.
However you can make things easier on yourself.
Ive found my best ES and SD are observed when my powder charge is able to completely fill the case and even a very slight compression is achieved. The less airspace is in the case the more consistent the load will be. It’s just that simple.
I used to use varget but discovered cfe223 and I haven’t looked back. Way more velocity potential for the bullet weights I use. However varget has proven itself for many in the 308 so I’m sure you’ll be able to tune in a powder charge perfect for your rifle.
And the 168 grain amax is arguably one of the best shooting bullets for 308 ever manufactured. For 600 meters or less the 168 grain amax is king in my opinion,especially once cost is considered.
I found the amax and the hpbt shot best with a 20 to 30 thou jump.
If you’ve got any specifics just shoot me a pm. If I can help I’m happy to

[LoneWolf]

First off, read this thread: http://www.savageshooters.com/showth...ght-reloading)

Second, take your time. You don't just pick a load and cross your fingers. I use this OCW method with great success to determine the charge range the rifle likes based on groups. Then I put it on a chronograph and tighten up the numbers through seating depth etc. I have found bullets that barrels don't like, usually due to their lack of quality and inconsistency be it weight or BC or whatever, but I've never been able to blame it on powder or primer.

You can get decent to good accuracy with the brass you've chosen, but again accuracy comes from consistency. Quality components make obtaining accuracy a much easier process. I prefer Lapua brass for this process, but if you take your time and ensure everything is done correctly with the right tools, you can still find success.

Brass should be full length sized after every firing with the shoulder bumped back .002, and neck tension set at .002-.003. I start every barrel jumping the bullet .020 off the lands and will tune +/- .005 at a time from their to tighten up horizontal and chrono numbers.

My full process from fired to loaded ammo:

1: Deprime - I use a universal de-capping die and perform this step separate from sizing
2: Dry tumble clean
3: Anneal (I use an AMP Machine, but this step is not required in the beginning. This is primarily for longevity of brass and maintaining neck tension consistency between firings)
4: FL Size with Redding Type S FL Bushing Die. (Specs addressed above)
5: Tumble sizing lube off
6: Prime
7: Run through a Sinclair Mandrel Die with neck turning Mandrel .002 under bullet diameter
8: Trim, Chamfer, Debur. (I use a Giruard Trimmer now, but started with an RCBS trim pro-2 with 3 in 1 cutter)
9: Throw charges (I run an Auto-Trickler Combo on a lab grade scale. The RCBS Chargemaster Lite is a solid investment and quite consitent), I measure to the Kernel, but you can gain accuracy if you can at least maintain a +/-.1grs variation or less (This is argued by many, but I know it works...). (Not a necessity for most to weigh charges to the kernel, but I compete and consistency is everything)
10: Forster Benchrest seater die (I don't use the micrometer seater dies, although they are pretty nice. I don't feel it's a necessity) Seat bullets to desire depth to maintain consistent distance to the lands. I measure my rounds base to bullet OGIVE as the OGIVE is more consistent than the tip. Using Overall Length can vary by .010-.020 or more and will drive you insane trying to get things matched up. Higher quality bullets maintain these measurement more consistently.

If I'm doing load dev I will pick my test range to be in the velocity range I desire. I test charges in .2grs increments as it allows me to see where the charge nodes are and how large the node is. However, if your system of dropping and weighing powder is less accurate I would recommend using .5grs increments instead.

Lastly, although I see success with virgin brass or sized brass from another rifle. I have never seen the full advantage until the second firing in the same chamber. That's when things really start to tighten up. Ensuring each component is from the came lot is another piece of the puzzle to think about. These are things that cancel out a lot of the headaches along the way.

[wbm]

I have never had a 308 that did not favor 4064.good luck

Along with me and several thousand other 308 shooters for a few decades.

[LoneWolf]

Along with me and several thousand other 308 shooters for a few decades.

I agree 4064 is a great powder for the 308 and ran it myself in the beginning. I believe Varget has better temp stability though.

[CFJunkie]

Lone Wolf,

You're right!
Varget has much better temperature stability than any other 'extreme powder' - a total of 4 fps change across the 0 to 125 degree F. temperature range for a .308.
H4895, also an 'extreme powder', has about 8 fps change over the same range and that is also very stable.
In contrast, IMR4064 has around 150 fps change across the same temperature range.

IMR4064 has been my go to powder for .308s for several years, although I also use a lot of H4895.
I have found that the new IMR4166 Enduron powder is a pretty temperature stable powder and rivals IMR4064 for accuracy in my .308s.
IMR4166 Enduron has about 20 to 25 fps change across the 0 to 125 degree F. temperature range.