How do you make the jump?

Cornivorus

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So I'm loading for my 7mm08 and using 165 gr. Sierra Game Changer and there isn't much load data available. I have some data from Sierra , but it doesn't give the powder I am wanting to load(Imr8208xbr).

Hogdon lists the 162 gr, A-max with this powder and a Coal of 2.875". My Tikka being a long action can handle up to 2.988" to the lands.

My question is what is your process for making the jump from a published Coal to the longer length of say 2.96" or about 20 or 30 thou off?

I've loaded up some with a Coal of 2.875" and they shot fine ie no pressure signs yet. I'm still below the published max for the 162 gr. A-max with velocity only 2575fps. How big of a jump in length can I go, if I load the last load I have tested, say 2.9" then 2.925"? Is 25 thou too big of a jump when incrementing ?
 
I use a Hornady OAL gage and bullet comparators an load pretty much everything .020 off (20 thou). It's almost always longer than COAL and I use the Cartridge Base to Ogive or "CBTO" measurement as my standard. As long as they fit in the mag and (like 243winxb says) you got a cross section of the bullet's diameter in the neck.
 
Having enough bullet is no problem with the 165 TGK, these things are very long for caliber, almost as long as the 30 cal. 212 gr. Eldx.

My main concern is not causing pressure spikes vs a given load by moving seating depth, but after seeing that Berger recommends going in .040 " steps I feel ok with the .025" steps I'm trying.
 
I start @ .010 off of touch and shoot 2-3 shot groups round robin. Increments are .005" deeper in case, til I'm .040" off lands.

If that doesn't work, I do the standard Berger test, depending on it's effect on case capacity. You never know just how much jump a combination requires, to shoot well. Some rifles are just not capable of tight groups with some components, or any components.

IMG_20190618_154326186.jpg
 
Seating a bullet farther out will not give you pressure spikes unless it touches the lands. As long as you're not touching the lands you'll be ok. Going the other way, seating deeper, *will* raise pressure but how much is hard to say. Knowing how much powder to reduce when seating deeper is a guessing game, or reloading voodoo as I call it. Depends on the bullet shape and type of propellant and how close to max you are before seating deeper. Could be a grain or two, or even 3 or 4. Err with caution is all I can say!
Cheers,
crkckr
 
Ok, I know, this is apples/oranges but here's a quote from a Speer reloading manual regarding 9mm pistol ammo:
"Speer #10 Manual, pg. 349, regarding pressures and neck tension on 9mm cases, "If the bullet is easily moved deeper into the case, malfunctions may occur. More importantly, loads that produced 28,000 CUP went to 62,000 CUP when bullets were purposely seated .030" deeper!" This is repeated in Speer 11 on page 385, 9mm Data.
Cheers,
crkckr
 
So I'm loading for my 7mm08 and using 165 gr. Sierra Game Changer and there isn't much load data available. I have some data from Sierra , but it doesn't give the powder I am wanting to load(Imr8208xbr).

Hogdon lists the 162 gr, A-max with this powder and a Coal of 2.875". My Tikka being a long action can handle up to 2.988" to the lands.

My question is what is your process for making the jump from a published Coal to the longer length of say 2.96" or about 20 or 30 thou off?

I've loaded up some with a Coal of 2.875" and they shot fine ie no pressure signs yet. I'm still below the published max for the 162 gr. A-max with velocity only 2575fps. How big of a jump in length can I go, if I load the last load I have tested, say 2.9" then 2.925"? Is 25 thou too big of a jump when incrementing ?
I shoot 130 Grain Gamechangers .010 off the lands in my rifle. I would do some test loads at .010, .020, .030 and see. It makes a big difference in my rifle.
 
A rough seating depth is one of the first things I do, right after figuring out my maximum charge weight. I find the max charge weight and pick and arbitrary charge weight about 2% under that for testing loads for seating depth. Then follow the Berger procedure for finding a rough seating depth. Sometimes you'll have a gun that will only shoot with a 1/4" jump. You just don't know till you test.
 
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