7mm08 set up for reloading

[williaada]

Looking for some input on what to set my COAL for a 7mm08. I can chamber and cycle dummy rounds from 2.850-2.900 with out issue the factory brand ammo all measured between 2.750 and 2.780.

Is there any reason to be longer than the SAMI standards?

 

[bmart2622]

Yeah, if your rifle likes more jump. Longer seating depth frees up case capacity as well but being closer to the lands also increases pressure so you will just have to try some things and see where pressure is and what kind of jump the rifle/bullet combo likes

 

[TxLite]

I load longer because that’s where my rifle likes the bullets to be. I also do it to free up case capacity. Find what your rifle likes and roll with it

 

[EdP]

Being closer to the lands only increases pressure when the lands are approached in the final few thousandths or closer. Otherwise, loading longer reduces pressure. There is info on line and in Brian Litz' book on this phenomenon. As described by Tx above, some rifle/bullet combos like a long jump, some like it short. Find what works best in your rifle and hope they will cycle. Be aware that other issues will arise if there is not enough bullet in the neck for good neck tension.

 

[Gargoyle]

Determine your DTL. Know how?
Are you limited in COAL by magazine?
Do your longer COAL dummy rounds have land marks on the bullets?

Pressure doesn't build to any meaningful difference loading close to the lands, on at the lands. I don't know why this is parroted all over the shooting forums. Competition shooters will shoot jam + .010-.20. Hunters shouldn't load jam for the obvious reason hunters don't always shoot the chambered round. The potential for the bullet to stay in the rifling while the case extracts is real.

 

[bmart2622]

Determine your DTL. Know how?
Are you limited in COAL by magazine?
Do your longer COAL dummy rounds have land marks on the bullets?

Pressure doesn't build to any meaningful difference loading close to the lands, on at the lands. I don't know why this is parroted all over the shooting forums. Competition shooters will shoot jam + .010-.20. Hunters shouldn't load jam for the obvious reason hunters don't always shoot the chambered round. The potential for the bullet to stay in the rifling while the case extracts is real.

So does velocity increase or decrease as you get closer to the lands?

 

[EdP]

So does velocity increase or decrease as you get closer to the lands?

This link should answer your question much better than I can: https://bergerbullets.com/effects-o...coal-and-cartridge-base-to-ogive-cbto-part-1/

 

[N2TRKYS]

I use Nosler bullets. I’ve had excellent results following Nosler’s load data and their test COAL. This has worked in every rifle and cartridge I load(over a dozen rifles).

My 7-08 shoots 140 grain Accubonds 2850fps from a factory 20” barrel.

 

[Rob5589]

Seating long will help with powder capacity if using a longer bullet like the 150 eldx. Not a bad thing to have some mag room in order to play with the depth some. For reference, one of my T3's run at 2.8 factory specs; the other 2.905 with a long action bolt stop and mag. Same bullet (120 ttsx) but different powder.

 

[Gargoyle]

So does velocity increase or decrease as you get closer to the lands?

I've not noticed much, but I'm moreso focused on pressure signs & ES/SD when load developing. All my cup & core bullet load development starts at the lands. Find precision by .010 jumps from the hands. Bergers & Hornadys have been "at the lands" performers, Hammer copper monos love .030-.120" off the lands.

I was off on my DTL on a .308 rig once. I was shooting jam + .020 ish with 168 Amax. Most accurate I ever got anything to shoot out of that gun. When I seated them off the lands the group sizes increased noticeably.

 

[bmart2622]

It increases

 

[EdP]

It increases

Did you not read the info in the link? Not understand it? Not agree?

 

[bmart2622]

It just simply hasnt been what Ive found in the many dozens of loads Ive messed with actually shooting over a chrono. Theoretical data on paper may differ but my real world data has always shown an increase in velocity when you seat longer.

 

[Harvey_NW]

Is there any reason to be longer than the SAMI standards?

If you're getting into compression and need more room for powder to achieve a higher velocity, sure. Otherwise, not really. Load it to a functional length and shoot a large sample size. Magical seating depths and powder charges typically don't exist when taken to a statistically significant sample size, and you'll find everyone that claims "XX brand likes .XX amount of jump in their rifle" doesn't have proof.

 

[waitforit]

My 2c,
Hammer bullets don't care about jump. Shoot great in multiple rifles whether I load long or to spec.
ELD-M seem more particular. My best loads in 2 different rifles, 2 different calibers is 0.040 - 0.050" off the lands. Closer is worse in every instance for me.

 

[Gargoyle]

It just simply hasnt been what Ive found in the many dozens of loads Ive messed with actually shooting over a chrono. Theoretical data on paper may differ but my real world data has always shown an increase in velocity when you seat longer.

WUT?

 

[EdP]

WUT?

Exactly!!! Brian Litz, who wrote the article, is the ballistics engineer for Berger bullets and a very experienced long range shooting competitor. He is NOT someone just writing theoretically. I suggest that if your results don't match what Brian said should be happening you should be asking "what am I doing wrong?" rather than discounting what Brian has said (and spreading incorrect information on a public forum).

 

[bmart2622]

Im not discounting what Brian says at all, hes a smart guy. But Im also not going to discount what my results have shown over thousands of shots. Im not doing a thing wrong with the way I reload!! And not spreading any incorrect information.

 

[Harvey_NW]

Exactly!!! Brian Litz, who wrote the article, is the ballistics engineer for Berger bullets and a very experienced long range shooting competitor. He is NOT someone just writing theoretically. I suggest that if your results don't match what Brian said should be happening you should be asking "what am I doing wrong?" rather than discounting what Brian has said (and spreading incorrect information on a public forum).

Bryan Litz also used to believe in using seating depth to change the precision, or "tune", a load. You should listen to his more recent findings. Not saying there isn't merit to past publications, but as we progress with technology and experiments things change, and he admits he's been wrong.

 

[EdP]

And not spreading any incorrect information.

Perhaps not, but please consider that you answered a question definitively based on your experience, but your answer differs from what is in the available literature and what is generally accepted. I have no issue with you sharing your experience, that sharing is what we are all here for. When you respond to a question based on your experience and it differs from what is generally accepted, I think the response deserves a caveat so the person who asked understands it is based only on your experience. That would make your answer more complete.