Seating depth sweet spot

Wachsmann

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Feb 1, 2008
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Meridain, Idaho
One question if anyone care to answer or if they have seen this before... Is it common for a rifle to like the same amount of jump even with different bullets. Basically does a rifle like the same sweet spot for each bullet regardless of how its designed. So like my bergers I will have to check but I think they are .080 or 0.085 off the lands as well. I tested some 142 LRAB and the best group came up also at .085 off the lands as well. So even using something like a amax should I be able to get a lands depth and then back it up .085 off and produce similar results. Even though the OAL length may be different with different bullets but maintain that 0.085 off the lands and produce good results. Just curious if anyone has seen where there gun likes a certain amount of jump or it may be jammed into the lands that gives them the same results for multiple bullets.
 
I pick what I think is my best prospect in bullet and do full seating testing with that.
Where I change bullets I take one of two paths:
-If the bullets are like in ogive type(tan to tan, sec to sec), the second bullet begins at the same CBTO as the fully tested bullet. Then I fine tweak test for group shaping.
-If the bullets are different in ogive type, I also do full testing with the new bullet.

For me so far, bullet weight changes haven't affected best tested seating(coarse). Nor have powder or primer changes. And while I'm off the lands(OTL), throat erosion hasn't mattered, even while a bullet's relationship to lands is changing with use.
Given this, I cannot figure out what seating is actually doing tune-wise. Every common notion fails tests. I just know CBTO is the single biggest factor in dialing <1/2moa from a hunting gun/cartridge.
 
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