.308 questions, so chime in please

[Michael Eichele]

I'm sorry Darkker, your still haven't proved that burn rate doesn't matter. Or that H4350 is over loaded.

 

[Michael Eichele]

This really isn't worth arguing over anyway. Everything has its limits. When bolts open and extract with ease, cases aren't damaged, primers aren't flat or cratered, primer pockets are tight after several firings, then loads are within the limits of the equipment and components used. SAMMI is a guideline for sure. They also factor in equipment and components that may not be of good quality. Overloading is where you're damaging equipment and/or components.

Maybe you could start another thread on this subject and share your experience and expertise in this area. Elaborate and include as many details as possible. I'm not saying you're wrong but I am asking you to support your few comments with more information. We have hijacked this thread for sure. Let's move it.

M

 

[Canadian Bushman]

My biggest concerns with the 08 chamber is the neck and headspace. Im killing myself managing neck hardening right now because of my .343 neck. I think my lapua brass measured .336 loaded and i turned it, big mistake.

I would select brass and a bullet first ( dont overlook the 208 amax and 215 hybrid ).

Then run a reamer based on saami spec with a neck .003-.004 above a loaded round and have it throated to a bullet ( you chose ) seated just above the neck shoulder junction.

As long as your smith headspaces it .001-.002 above the dummy you will be set.

P.S. The last batch of lapua brass i measured was small and would require minimum headspace set by saami.

 

[Trickymissfit]

Wow! Or should I say "woe is me" with all the data to be gleaned! I've been thinking a lot, and may surprise all of you. Thinking 208 grain bullets and things like that sends me into a thinking mode.

more later
gary

 

[Michael Eichele]

Wow! Or should I say "woe is me" with all the data to be gleaned! I've been thinking a lot, and may surprise all of you. Thinking 208 grain bullets and things like that sends me into a thinking mode.

more later
gary

Yeah. Especially IF the new 208 ELDM is really been improved to .670 G1. 2500-2600 is pretty realistic. 2650 in 26" tubes is possible but tough to achieve.

 

[Trickymissfit]

Yeah. Especially IF the new 208 ELDM is really been improved to .670 G1. 2500-2600 is pretty realistic. 2650 in 26" tubes is possible but tough to achieve.

food for thought:

* neck up the 6.5x55 to 30 caliber, and improve the case with a 30 degree shoulder. I think it's good for another 150 fps without going into over bore. (2775fps). This round is not new and has been done in the past by Dr. Arch for one.

* or the 7x57 case necked up to 30 caliber, and improved with a 40 degree shoulder. Expect .035" case shrinkage on fire forming, so this is going to give you an almost ideal neck length. Plus I think 2850fps is doable, but not much more. The actual case volume is not as great as it looks on paper, but the shoulder length is still about .140" longer. Kind half way between the .308 and the 30-06.

I thought about the .284 necked up to .308, and said to myself why? No better than the 30-06! With the case volume of the 7.62x51 being close to ideal with 150 grain bullets we see it start to fade with 190 grain and heavier bullets. This is where the 55mm and the 57mm cases will come to life. Yet most everybody already knows the 30BR is the most efficient case out there. I think a 55mm case with the 30BR numbers might just be the ticket.

gary

 

[Michael Eichele]

You can get factory dies for the 30-284. IMHO, if you want an improvement on the 308 without going long action, it's a fair option. 308x55 does sound interesting though. I'm considering a 308AI. I'm sure with H4350, it'd really scream.

 

[Canadian Bushman]

I thought i remember someone here pushing a 30br reamer to the 308 headspace dim for a 308 improved. For the life of me i cant remember who it was. (AZshooter maybe?)

With all the 6br variants now there are quite a few possibilities with this concept.

I imagine a 30brx pushed deep would be right behind a 300 wsm.

 

[Trickymissfit]

You can get factory dies for the 30-284. IMHO, if you want an improvement on the 308 without going long action, it's a fair option. 308x55 does sound interesting though. I'm considering a 308AI. I'm sure with H4350, it'd really scream.

The .284 has never been my cup of tea even though many guys have jumped on the bandwagon. Seen too many guys stuck with a white elephant when the case supply dried up. The 7x57 case will cycle thru a Savage short action, but I'll probably use the 112 action anyway. I have both actions in my safe as well as a 700 Remington. The 700 is already setup for a .378" case head, and I completely happy with the setup sans barrel. Plus the Savage is slightly longer in the middle.

The above being aside, the things that make me want to take a serious look at the 6.5x55 necked up case are neck length and volume gains from going the improved route. You can pretty much make a longer .308, but you can do better. The 7x57 improved after fire forming will give you roughly a .330" neck length. I personally would rather go the 30 degree route over the 40 degree shoulder angle. Now the shoulder length of the 7x57 improved will be about .215" longer than the .308. Personally about .065" more length than I really need. The .308 case gains almost nothing by improving it.

I'm also looking at one other case, but it's an odd ball. Plus will be hard to find.
gary