Berger seating depth ladder opinions

[Shane Lindsey]

If it were me, of your most consistent shots, I would work up to pressure and then fine tune with seating. I too have found that seating depth changed with charges weights and different powders. Different combos effecting harmonics I guess.

For mine with the 215, I loaded to max mag length for reliability. Put me at .060" off and then loaded up. Got to 77 gr H1000 in Norma brass with CCI250. That's a Rem 700 5R.

My Ruger at mag length is 3.335" to fit mag (don't even know how far that is off lands). That is within book loads and it shot a little less than a MOA.

My point is with regards to seating depth and the 215 is they are pretty forgiving at least that I have found.

Like any other rifle, not all bullets shoot in all barrels well.

 

[Alex Wheeler]

I recommend .005 increments. Seating depth nodes are not that far apart.

 

[Lonewolf74]

I did several seating depth test with the 215 bergers and 300wm and found a couple spots that seem to be sweet spots. .005 to .015 all shoot good groups then my very tightest groups came at .040 off.

I need more time to test and be certain but what it looks like to me is .040 gives best accuracy but .005-.015 is a more forgiving window, meaning I can seat at .005, .010 and .015 off and not see a difference on target.

I also think if I made some fine adjustment of .003 up and down from .010 off i could find a spot where it shot just as good as .040 off. Just need more time to test.

 

[Wolf76]

My 300 wm shoots those 215 Bergers sub half moa. Load is 77.9gr h1000, federal 215m, loaded very long @.006 off. This is on the hot side, so don't start there.
When developing a load, I try to determine the seating depth first, then powder charge. Generally work in groups of 10 thousandths and 90% of max max load. Never had much luck with cci and Winchester primers.
Barnes and accubond LR seem to like the jump. Standard cup/core 10-30 off. Bergers often tight to the lands.
Good luck.

 

[codym]

Since Norma has two case weights for 300 Win Mag, how much do your new Norma cases weigh?

I finally got around to weighing these, 214.-218 gns with average 216.9

Also I never subtracted .308 from my group sizes not that it matters a whole bunch but puts mb better goups well under 1/2 MOA at 200. I have heard so much conflicting info on OCW vs seating depth and what to do first. I think im gonna use this time to experiment with seating depth first (while I save up for a labradar) and once I have an idea what that does go back and find OCW. Find OCW and see if I then I have to fine tune seating depth again. It's summer and I don't have much going on so may as well play around with things and see what makes a difference and what doesnt.

 

[tbrice23]

You should probably measure groups from center to center (outside diameter minus .308,
1.047" group at 100 yards is one moa) just so everyone is speaking the same language.

I usually take my C-C measurement (at say 200) yards and divide by 2 and multiply by .95 , it works well at any distance .

 

[codym]

Yea I don't know what I was thinking I just took outside to outside and forgot to subtract the .308, so my 1' group was actualy .692. The only reason I even brought it it up is this is a factory rifle with bedding and a aftermarket trigger. I just don't know how much more I can reasonably expect. Anyway it's a good one to play around with and see how much seating depth will affect things before and after finding ocw.

 

[ShtrRdy]

I finally got around to weighing these, 214.-218 gns with average 216.9

That weight is Normas lighter weight 300 Win Mag brass

Were you able to get the 215 Hybrid to work for you?

 

[codym]

Yea I got it consistently .5 moa with 215 hybrids Norma brass and 75 gns of h-1000, .020 jump.

 

[Mikecr]

Did you back off from that 75gr powder load for this seating testing?

 

[codym]

No. I have refined my load process since this thread. I start just off the lands then do a a velocity ladder find the flat spot. From there I run a seating depth test going 10 deeper shooting groups at 300 yards. Usually 5 shot groups give you a good idea of what depth it likes. Then I will load 5 thou on either side of the best depth and try again. If it's still not where I want I will play with neck tension. I found the hybrids in my 6br/dashers 280 ai 300 win mags all like to be ran right at the lands or 20 thou off very consistently.

 

[ShtrRdy]

Did you back off from that 75gr powder load for this seating testing?

How much would you recommend backing off from the 75 gr charge weight on this case? Would 1 grain be enough?

 

[ShtrRdy]

Yea I got it consistently .5 moa with 215 hybrids Norma brass and 75 gns of h-1000, .020 jump.

What was the cartridge overall length you ended up with?

 

[codym]

I honestly don't remember, I'm sure I wrote the cbto measurement in the book, I will try to look it up if that will help you.

on your other Question I would start around 2 grains below max and do 1/2 grain increases until you find your max load for your rifle. Then decide if you want to dial in your powder charge or do a bullet seating depth first. I do my powder first using ocw ladders and looking for flats spots in the velocity over my labradar. Then I do my seating depth test with my optimal charge weight. For my rifle 75 grains was quite a bit below my max charge if my memory was correct. I would see no need to drop your powder charge to adjust seating depth unless maybe you were at a max charge with the bullet off the lands and wanted to try a hard jam.