212eldx in .308 hybrid cases?

[sgtsmmiii]

Thank you @45-90 for all of your time experimenting with these hybrid cases and sharing your knowledge.

Now, lets hear about how you're forming those 6mm Dasher cases.................... .

 

[straightshooter1]

As I've mentioned in another thread, I've sorted through 5 boxes of these hybrids. From the 5 boxes I received, 287 of them have the "24" headstamp, 158 have the "277 Fury", 87 have the "23" and 22 just have the "Sig" for a total of 554 cases altogether.

The 24's were the heaviest and the 10 of them that I fire formed had case volume of 56.3 grs H2O. Most of the 23's were in the same weight range as the 24's, but a few were substantially less. The "277 Fury"s were consistently way lighter than the 24's and those few Sig's were about the same as the Fury's. Once I fireform the Fury's I've loaded up, I suspect the case capacity will be more like ~57.5 grs of H2O due to that weight difference.

The ten 24's that I only fire formed produces really good results both on paper and in terms of SD's and ES's, which surprised me as I had loaded them with the same primers I had removed in order to anneal and size them up to a .308. But then, it's only 10 rounds fired.

 

[Bacarrat]

Have only gotten the 6.5CM to work well so far. My current load so far is 44.5gr H4350 with the 140 ELDM goind about 2900 with a 24" Proof. Going to load up some RL16 for tomorrow. Historically, it should be another 100fps according to my old barrel. Been saving RL16 since it's sometimes impossible to get and now it's crazy expensive when you do find it. That's easily with in if not faster then 6.5PRC speeds. Also tried one of my friends load with the 130gr bergers and 2000MR. Was running them around 3100FPS but it was too hot. Haven't too much at distance yet only about 20 rounds at 600 with the 6.5. Still trying to nail this 308 load. Not sure why it doesn't want to shoot well. Brass cases still under MOA with ammo I loaded over a year ago.

 

[ARShooter91]

I've noticed all my cases are either around 150grains with no primer or 161gr. The 161g cases take almost a grain less powder to achieve the same velocity. The lighter cases seem more consistent but I need to look at all my data to see if that holds up

 

[45-90]

Honest question(s) here...

Yes, the hybrid cases can handle stupid amounts of pressure. Can your primers? Kinda surprised that you don't have issues with pierced primers, or leaky ones etching the bolt face?

At what point does a steady diet of 'proof' loads start causing problems in the action ie lug set back, etc.?

Primers have not shown to be a problem at high pressures of 75k to 80k.
These are still rounded and all are high pressure loads, from 2 factory rifles with standard firing pins and springs.

Never pierced a primer, but if you hit 90,000 psi the teat will grow but the primer hardly flattened...the primer teat is a pressure indicator, ya don't want a slight increase over these.

Stainless steel case heads don't expand and leak gas around the primer, like brass.

The old Sig cases didn't have a year stamped on them.
They are a bit lighter, and some very consistent if weighed out, 58 pcs out of 100 were within just 1 grain total weight.
I have a few with the 22 yr and a new bunch with a 23 yr...the 23 yr are all Sig. I have none stamped Fury.
The 23 yr are a bit heavier also have powder stuck in the cases and needs to be blown out with compressed air.
LC was supposed to have begun production of hybrid cases, and may be why more variations of the case being offered.
LC always stamps year on case heads, as far as I know.
So it appears more are getting involved in the contracts of making them.

Meaning we'll have to be careful and aware with the volume of these cases...

With respect to 308 accuracy with all 3 cases the early Sig hybrid, Lapua LR, Lapua Palma SR, I did a small test .
A 10 shot group with each style of case on the same day with the same load, using 230 gr SMK 9 twist 22" barrel that the barrel liked.

The hybrid case had the lowest S/ D, and the best 10 shot group out of the three, followed by the Lapua LR cases...Plama cases were the worst.
Plama cases also lose 40 to 50 fps with the same powder charge.
So you have to up the powder charge to get the same velocity as the Lapua LR cases.

Which would mean the powder ignition is lacking and the higher S/Ds with this powder and less accuracy tend to prove that out.
So for all round consistency in all temperatures, and powder combos today I prefer LR primers in 308.
I have shot good groups with Palma cases yrs past, still have a few hundred new ones.

But from my experience I generally do not use or promote them, today.
But there are places where group shooters find during the spring & summer with a certain powder these Palma cases give the smallest groups. Use em where needed.